0000891014-22-000009 | 10-K | XBRL Viewer | Minerals Technologies INC

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CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 299.5	$ 367.7
Short-term investments, at cost which approximates market	4.9	4.1
Accounts receivable	367.8	369.0
Inventories	297.7	248.2
Prepaid expenses	41.2	35.4
Other current assets	17.4	9.2
Total current assets	1,028.5	1,033.6
Property, plant and equipment, less accumulated depreciation and depletion	1,049.1	1,039.6
Goodwill	907.5	808.5
Intangible assets	251.6	195.8
Deferred income taxes	23.0	25.3
Other assets and deferred charges	114.5	106.6
Total assets	3,374.2	3,209.4
Current liabilities:
Short-term debt	80.0	0.0
Current maturities of long-term debt	0.8	1.0
Accounts payable	196.1	148.3
Income tax payable	0.0	8.7
Accrued compensation and related items	57.9	60.3
Other current liabilities	85.0	77.5
Total current liabilities	419.8	295.8
Long-term debt, net of unamortized discount and deferred financing costs	936.2	933.2
Deferred income taxes	188.1	163.7
Accrued pension and post retirement benefits	114.3	179.0
Other non-current liabilities	136.3	139.0
Total liabilities	1,794.7	1,710.7
Shareholders' equity:
Preferred stock, without par value; 1,000,000 shares authorized; none issued	0.0	0.0
Common stock, par value at $0.10 per share; 100,000,000 shares authorized; Issued 49,347,347 shares in 2021 and 49,051,181 shares in 2020	4.9	4.9
Additional paid-in capital	474.2	453.3
Retained earnings	2,168.9	2,011.3
Accumulated other comprehensive loss	(333.6)	(308.3)
Less common stock held in treasury, at cost; 16,170,154 shares in 2021 and 15,168,994 shares in 2020	(775.1)	(700.4)
Total Minerals Technologies Inc. shareholders' equity	1,539.3	1,460.8
Non-controlling interests	40.2	37.9
Total shareholders' equity	1,579.5	1,498.7
Total liabilities and shareholders' equity	$ 3,374.2	$ 3,209.4

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Shareholders' equity:
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	49,347,347	49,051,181
Common stock held in treasury, shares (in shares)	16,170,154	15,168,994

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statements of Income [Abstract]
Net sales	$ 1,858.3	$ 1,594.8	$ 1,791.0
Cost of goods sold	1,411.8	1,189.4	1,350.4
Production margin	446.5	405.4	440.6
Marketing and administrative expenses	186.2	176.5	187.5
Research and development expenses	19.5	19.9	20.3
Acquisition-related expenses	4.0	3.1	0.0
Litigation expenses	0.0	10.4	10.9
Restructuring and other items, net	1.1	7.6	13.2
Income from operations	235.7	187.9	208.7
Interest expense, net	(37.2)	(38.2)	(43.2)
Non-cash pension settlement charge	(1.8)	(6.4)	0.0
Other non-operating income (deductions), net	5.6	(5.3)	(8.2)
Total non-operating deductions, net	(33.4)	(49.9)	(51.4)
Income from operations before tax and equity in earnings	202.3	138.0	157.3
Provision for taxes on income	36.6	24.4	22.8
Equity in earnings of affiliates, net of tax	2.8	2.2	1.9
Consolidated net income	168.5	115.8	136.4
Less: Net income attributable to non-controlling interests	4.1	3.4	3.7
Net income attributable to Minerals Technologies Inc. (MTI)	$ 164.4	$ 112.4	$ 132.7
Basic:
Income from operations attributable to MTI (in dollars per share)	$ 4.89	$ 3.29	$ 3.79
Diluted:
Income from operations attributable to MTI (in dollars per share)	4.86	3.29	3.78
Cash dividends declared per common share (in dollars per share)	$ 0.20	$ 0.20	$ 0.20
Shares used in computation of earnings per share:
Basic (in shares)	33.6	34.2	35.0
Diluted (in shares)	33.8	34.2	35.1

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Consolidated net income	$ 168.5	$ 115.8	$ 136.4
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(78.9)	10.9	(29.9)
Pension and postretirement plan adjustments	45.2	(18.7)	(16.1)
Unrealized gain (loss) on cash flow hedges	8.4	(8.5)	0.2
Total other comprehensive income (loss), net of tax	(25.3)	(16.3)	(45.8)
Total comprehensive income including non-controlling interests	143.2	99.5	90.6
Less: Net income attributable to non-controlling interests	4.1	3.4	3.7
Less: Foreign currency translation adjustments attributable to non-controlling interests	(0.1)	1.7	0.0
Comprehensive income attributable to non-controlling interests	4.0	5.1	3.7
Comprehensive income attributable to Minerals Technologies Inc.	$ 139.2	$ 94.4	$ 86.9

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Consolidated net income	$ 168.5	$ 115.8	$ 136.4
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	94.6	93.9	98.4
Loss on disposal of property, plant and equipment	0.4	0.2	1.9
Deferred income taxes	2.1	(2.7)	(1.4)
Pension amortization and settlement loss	13.1	13.1	9.2
Provision for bad debts	0.9	2.6	6.3
Stock-based compensation	10.7	10.2	8.1
Asset write-downs	0.7	7.1	7.5
Reduction of right of use asset	12.3	12.3	12.7
Other non-cash items	(2.8)	(2.2)	(1.9)
Changes in operating assets and liabilities
Accounts receivable	(7.2)	13.7	9.9
Inventories	(58.2)	8.3	(16.0)
Pension plan funding	(11.1)	(12.2)	(7.7)
Accounts payable	43.0	(16.7)	(5.1)
Restructuring liabilities	(1.4)	(1.2)	2.4
Income taxes payable	(6.0)	3.9	2.5
Prepaid expenses and other	(27.2)	(5.5)	(24.9)
Net cash provided by operating activities	232.4	240.6	238.3
Investing Activities:
Purchases of property, plant and equipment	(86.0)	(66.8)	(65.0)
Cash paid for acquisitions, net of cash acquired	(194.4)	(9.2)	0.0
Proceeds from sale of assets	0.7	0.7	0.0
Purchases of short-term investments	(9.4)	(8.7)	(5.5)
Proceeds from sale of short-term investments	8.3	5.3	7.7
Other investing activities	2.2	0.0	0.8
Net cash used in investing activities	(278.6)	(78.7)	(62.0)
Financing Activities:
Long-term debt issuance	0.0	400.0	0.0
Debt issuance costs	0.0	(6.4)	0.0
Repayment of long-term debt	(1.2)	(290.1)	(88.2)
Proceeds from issuance of short-term debt	100.5	0.0	0.0
Repayment of short-term debt	(20.5)	(101.2)	(4.0)
Purchase of common stock for treasury	(74.7)	(40.7)	(41.0)
Proceeds from issuance of stock under option plan	12.8	3.2	2.2
Tax withholding payments for stock-based compensation	(2.7)	(2.0)	(1.7)
Dividends paid to non-controlling interests	(1.8)	(0.7)	(4.2)
Capital contribution from non-controlling interests	0.0	1.7	0.6
Cash dividends paid	(6.8)	(6.8)	(7.0)
Net cash provided by (used in) financing activities	5.6	(43.0)	(143.3)
Effect of exchange rate changes on cash and cash equivalents	(27.6)	7.2	(0.2)
Net increase (decrease) in cash and cash equivalents	(68.2)	126.1	32.8
Cash and cash equivalents at beginning of period	367.7	241.6	208.8
Cash and cash equivalents at end of period	299.5	367.7	241.6
Non-cash financing activities
Treasury stock purchases settled after period end	$ 0.5	$ 1.8	$ 1.1

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Non-controlling Interests [Member]	Total	Cumulative Effect, Period of Adoption, Adjustment [Member] Common Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Additional Paid-in Capital [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Treasury Stock [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Non-controlling Interests [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance at Dec. 31, 2018	$ 4.9	$ 431.9	$ 1,769.1	$ (233.7)	$ (618.7)	$ 31.8	$ 1,385.3
Balance (ASU 2018-02 [Member]) at Dec. 31, 2018								$ 0.0	$ 0.0	$ 10.9	$ (10.9)	$ 0.0	$ 0.0	$ 0.0
Net income	0.0	0.0	132.7	0.0	0.0	3.7	136.4
Other comprehensive loss	0.0	0.0	0.0	(45.8)	0.0	0.0	(45.8)
Dividends declared	0.0	0.0	(7.0)	0.0	0.0	0.0	(7.0)
Dividends paid to non-controlling interests	0.0	0.0	0.0	0.0	0.0	(4.2)	(4.2)
Capital contribution from non-controlling interests	0.0	0.0	0.0	0.0	0.0	0.6	0.6
Issuance of shares pursuant to employee stock compensation plans	0.0	2.2	0.0	0.0	0.0	0.0	2.2
Purchase of common stock for treasury	0.0	0.0	0.0	0.0	(41.0)	0.0	(41.0)
Stock-based compensation	0.0	8.1	0.0	0.0	0.0	0.0	8.1
Balance at Dec. 31, 2019	4.9	442.2	1,905.7	(290.4)	(659.7)	31.9	1,434.6
Net income	0.0	0.0	112.4	0.0	0.0	3.4	115.8
Other comprehensive loss	0.0	0.0	0.0	(17.9)	0.0	1.6	(16.3)
Dividends declared	0.0	0.0	(6.8)	0.0	0.0	0.0	(6.8)
Dividends paid to non-controlling interests	0.0	0.0	0.0	0.0	0.0	(0.7)	(0.7)
Capital contribution from non-controlling interests	0.0	0.0	0.0	0.0	0.0	1.7	1.7
Issuance of shares pursuant to employee stock compensation plans	0.0	3.2	0.0	0.0	0.0	0.0	3.2
Purchase of common stock for treasury	0.0	0.0	0.0	0.0	(40.7)	0.0	(40.7)
Stock-based compensation	0.0	10.2	0.0	0.0	0.0	0.0	10.2
Conversion of RSU's for tax withholding	0.0	(2.3)	0.0	0.0	0.0	0.0	(2.3)
Balance at Dec. 31, 2020	4.9	453.3	2,011.3	(308.3)	(700.4)	37.9	1,498.7
Net income	0.0	0.0	164.4	0.0	0.0	4.1	168.5
Other comprehensive loss	0.0	0.0	0.0	(25.3)	0.0	0.0	(25.3)
Dividends declared	0.0	0.0	(6.8)	0.0	0.0	0.0	(6.8)
Dividends paid to non-controlling interests	0.0	0.0	0.0	0.0	0.0	(1.8)	(1.8)
Issuance of shares pursuant to employee stock compensation plans	0.0	12.8	0.0	0.0	0.0	0.0	12.8
Purchase of common stock for treasury	0.0	0.0	0.0	0.0	(74.7)	0.0	(74.7)
Stock-based compensation	0.0	10.7	0.0	0.0	0.0	0.0	10.7
Conversion of RSU's for tax withholding	0.0	(2.6)	0.0	0.0	0.0	0.0	(2.6)
Balance at Dec. 31, 2021	$ 4.9	$ 474.2	$ 2,168.9	$ (333.6)	$ (775.1)	$ 40.2	$ 1,579.5

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2021
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 1. Summary of Significant Accounting Policies Business Minerals Technologies Inc. (the "Company") is a resource- and technology-based company that develops, produces and markets on a worldwide basis a broad range of specialty mineral, mineral-based and synthetic mineral products and supporting systems and services. Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company, its wholly and majority-owned subsidiaries, as well as variable interest entities for which the Company is the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The Company employs accounting policies that are in accordance with U.S. generally accepted accounting principles and require management to make estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reported period. Significant estimates include those related to revenue recognition, valuation of long-lived assets, goodwill and other intangible assets, pension plan assumptions, income tax, and litigation and environmental liabilities. Actual results could differ from those estimates. Cash Equivalents and Short-term Investments The Company considers all highly liquid investments with original maturities of three months or less to be cash equivalents. Short-term investments consist of financial instruments, mainly bank deposits, with original maturities beyond three months, but less than twelve months. Short-term investments amounted to $4.9 million and $4.1 million at December 31, 2021 and 2020, respectively. There were no unrealized holding gains and losses on the short-term bank investments held at December 31, 2021. Trade Accounts Receivable Trade accounts receivables are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company's best estimate of the amount of probable credit losses in the Company's existing accounts receivable. The Company determines the allowance based on historical write-off experience and specific allowances for bankrupt customers. The Company also analyzes the collection history and financial condition of its other customers, considering current industry conditions and determines whether an allowance needs to be established. The Company reviews its allowance for doubtful accounts monthly. Past due balances over 90 days based on payment terms are reviewed individually for collectability. Allowance for doubtful accounts was $15.0 million at both December 31, 2021 and 2020. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The Company does not have any off-balance-sheet credit exposure related to its customers. Inventories Inventories are valued at the lower of cost or market. Cost is determined by the first-in, first-out (FIFO) method. Additionally, items such as idle facility expense, excessive spoilage, freight handling costs, and re-handling costs are recognized as current period charges. The allocation of fixed production overheads to the costs of conversion are based upon the normal capacity of the production facility. Fixed overhead costs associated with idle capacity are expensed as incurred. Property, Plant and Equipment Property, plant and equipment are recorded at cost. Significant improvements are capitalized, while maintenance and repair expenditures are charged to operations as incurred. The Company capitalizes interest cost as a component of construction in progress. The straight-line method of depreciation is used for substantially all of the assets for financial reporting purposes, except for mining related equipment which uses units-of-production method. The annual rates of depreciation are 3% - 6.67% for buildings, 6.67% - 12.5% for machinery and equipment, 8% - 12.5% for furniture and fixtures and 12.5% - 25% for computer equipment and software-related assets. The estimated useful lives of our PCC production facilities and machinery and equipment pertaining to our natural stone mining and processing plants and our chemical plants are 15 years. Property, plant and equipment are depreciated over their useful lives. Useful lives are based on management's estimates of the period that the assets can generate revenue, which does not necessarily coincide with the remaining term of a customer's contractual obligation to purchase products made using those assets. The Company's sales of PCC are predominantly pursuant to long-term evergreen contracts, initially ten years in length, with paper mills at which the Company operates satellite PCC plants. The terms of many of these agreements have been extended, often in connection with an expansion of the satellite PCC plant. Failure of a PCC customer to renew an agreement or continue to purchase PCC from a Company facility could result in an impairment of assets charge or accelerated depreciation at such facility. Depletion of mineral reserves is determined on a unit-of-extraction basis for financial reporting purposes, based upon proven and probable reserves, and generally on a percentage depletion basis for tax purposes. Stripping Costs Incurred During Production Stripping costs are those costs incurred for the removal of waste materials for the purpose of accessing ore body that will be produced commercially. Stripping costs incurred during the production phase of a mine are variable costs that are included in the costs of inventory produced during the period that the stripping costs are incurred. Accounting for the Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, the Company estimates the undiscounted future cash flows (excluding interest), resulting from the use of the asset and its ultimate disposition. If the sum of the undiscounted cash flows (excluding interest) is less than the carrying value, the Company recognizes an impairment loss, measured as the amount by which the carrying value exceeds the fair value of the asset, determined principally using discounted cash flows. Goodwill and Other Intangible Assets Goodwill represents the excess of purchase price and related costs over the value assigned to the net tangible and identifiable intangible assets of businesses acquired. Goodwill is not amortized, but instead assessed for impairment. Intangible assets with estimable useful lives are amortized on a straight-line basis over their respective estimated lives to the estimated residual values, and reviewed for impairment. The Company performs a qualitative assessment for each of its reporting units to determine if the two-step process for impairment testing is required. If the Company determines that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company would then evaluate the recoverability of goodwill using a two-step impairment test approach at the reporting unit level. In the first step, the fair value for the reporting unit is compared to its book value including goodwill. In the case that the fair value of the reporting unit is less than book value, a second step is performed which compares the fair value of the reporting unit's goodwill to the book value of the goodwill. The fair value for the goodwill is determined based on the difference between the fair values of the reporting unit and the net fair values of the identifiable assets and liabilities of such reporting unit. If the fair value of the goodwill is less than the book value, the difference is recognized as impairment. In addition to the assessment of goodwill impairment, the Company also reviews its other identifiable intangibles for impairment. Each year, the Company reviews whether events or changes in circumstances could indicate that a long-lived asset's carrying amount may not be recoverable. Should such events occur, the value of intangibles not recoverable would be recognized as impairment. Investment in Joint Ventures The Company uses the equity method of accounting to incorporate the results of its investments in companies in which it has significant influence but does not control; and cost method of accounting in companies in which it cannot exercise significant control. The Company records the equity in earnings of its investments in joint ventures on a one-month lag. At December 31, 2021 and 2020, the book value of the Company’s equity method investments was $17.5 million and $17.0 million. Accounting for Asset Retirement Obligations The Company provides for obligations associated with the retirement of long-lived assets and the associated asset retirement costs. The fair value of a liability for an asset retirement obligation is recognized in the period in which it is incurred if a reasonable estimate of fair value can be made. The associated asset retirement costs are capitalized as part of the carrying amount of the long-lived asset. The Company also provides for legal obligations to perform asset retirement activities where timing or methods of settlement are conditional on future events. The Company also records liabilities related to land reclamation as a part of the asset retirement obligations. The Company mines land for various minerals using a surface-mining process that requires the removal of overburden. In many instances, the Company is obligated to restore the land upon completion of the mining activity. As the overburden is removed, the Company recognizes this liability for land reclamation based on the estimated fair value of the obligation. The obligation is adjusted to reflect the passage of time and changes in estimated future cash outflows. Fair Value of Financial Instruments The recorded amounts of cash and cash equivalents, receivables, short-term borrowings, accounts payable, accrued interest, and variable-rate long-term debt approximate fair value because of the short maturity of those instruments or the variable nature of underlying interest rates. Short-term investments are recorded at cost, which approximates fair market value. Derivative Financial Instruments The Company records derivative financial instruments which are used to hedge certain foreign exchange risk at fair value on the balance sheet. See Note 12 for a full description of the Company's hedging activities and related accounting policies. Revenue Recognition Revenue is recognized at the point in time when the customer obtains control of the promised goods or services in an amount that reflects the consideration we expect to receive in exchange for those goods or services. The Company's revenues are primarily derived from the sale of products. Our primary performance obligation is satisfied upon shipment or delivery to our customer based on written sales terms, which is also when control is transferred. Revenues from sales of equipment are recorded upon completion of installation and transfer of control to the customer. Revenue where our performance obligations are satisfied in phases is recognized over time using certain input measures based on the measurement of the value transferred to the customer, including milestones achieved. Revenues from services are recorded when the services are performed. In most of our PCC contracts, the price per ton is based upon the total number of tons sold to the customer during the year. Under those contracts, the price billed to the customer for shipments during the year is based on periodic estimates of the total annual volume that will be sold to the customer. Revenues are adjusted at the end of each year to reflect the actual volume sold. There were no significant revenue adjustments in the fourth quarter of 2021 and 2020, respectively. We have consignment arrangements with certain customers in our Refractories segment. Revenues for these transactions are recorded when the consigned products are consumed by the customer. Foreign Currency The assets and liabilities of the Company's international subsidiaries are translated into U.S. dollars using exchange rates at the respective balance sheet date. The resulting translation adjustments are recorded in accumulated other comprehensive income (loss) in shareholders' equity. Income statement items are generally translated at monthly average exchange rates prevailing during the period. International subsidiaries operating in highly inflationary economies translate non-monetary assets at historical rates, while net monetary assets are translated at current rates, with the resulting translation adjustments included in net income. At December 31, 2021, the Company had no international subsidiaries operating in highly inflationary economies. Income Taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The Company operates in multiple taxing jurisdictions, both within the U.S. and outside the U.S. In certain situations, a taxing authority may challenge positions that the Company has adopted in its income tax filings. The Company regularly assesses its tax position for such transactions and includes reserves for those differences in position. The reserves are utilized or reversed once the statute of limitations has expired or the matter is otherwise resolved. The application of income tax law is inherently complex. Laws and regulations in this area are voluminous and are often ambiguous. As such, we are required to make many subjective assumptions and judgments regarding our income tax exposures. Interpretations of and guidance surrounding income tax laws and regulations change over time. As such, changes in our subjective assumptions and judgments can materially affect amounts recognized in the consolidated balance sheets and statements of operations. The Company's accounting policy is to recognize interest and penalties as part of its provision for income taxes. See Note 8 for additional detail on our uncertain tax positions. The accompanying financial statements do not include a provision for foreign withholding taxes on international subsidiaries' unremitted earnings, which are expected to be permanently reinvested overseas. Research and Development Research and development costs are expensed as incurred. Accounting for Stock-Based Compensation The Company recognizes compensation expense for share-based awards based upon the grant date fair value over the vesting period. Pension and Post-retirement Benefits The Company has defined benefit pension plans covering the majority of its employees. The benefits are generally based on years of service and an employee's modified career earnings. The Company also provides post-retirement healthcare benefits for the majority of its retirees and employees in the United States. The Company measures the costs of its obligation based on its best estimate. The net periodic costs are recognized as employees render the services necessary to earn the post-retirement benefits. Environmental Expenditures that relate to current operations are expensed or capitalized as appropriate. Expenditures that relate to an existing condition caused by past operations and which do not contribute to current or future revenue generation are expensed. Liabilities are recorded when it is probable the Company will be obligated to pay amounts for environmental site evaluation, remediation or related costs, and such amounts can be reasonably estimated. Earnings Per Share Basic earnings per share have been computed based upon the weighted average number of common shares outstanding during the period. Diluted earnings per share have been computed based upon the weighted average number of common shares outstanding during the period assuming the issuance of common shares for all potentially dilutive common shares outstanding. Subsequent Events The Company has evaluated for subsequent events through the date of issuance of its financial statements. Recently Issued Accounting Standards Changes to accounting principles generally accepted in the United States of America (U.S. GAAP) are established by the Financial Accounting Standards Board (FASB) in the form of accounting standards updates (ASUs) to the FASB’s Accounting Standards Codification. The Company considers the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on our consolidated financial position and results of operations. Adoption of Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU 2019-12, "Simplifying the Accounting for Income Taxes", to simplify the accounting for income taxes and improve consistent application by clarifying or amending existing guidance. The Company adopted this guidance on January 1, 2021. Adoption of this standard did not have a material impact on the Company's consolidated financial statements. Adoption of Investments - Equity Securities, Investments - Equity Method and Joint Ventures, and Derivatives and Hedging In January 2020, the FASB issued ASU 2020-01, "Investments - Equity Securities, Investments - Equity Method and Joint Ventures, and Derivatives and Hedging", which addresses the accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. The Company adopted this guidance on January 1, 2021. Adoption of this standard did not have a material impact on the Company's consolidated financial statements.

Leases

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Leases

Note 2. Leases

We determine if an arrangement is a lease at inception. The Company has operating leases for premises, equipment, rail cars and automobiles. Our leases have remaining lease terms of 1 year to 50 years, some of which may include options to extend the leases further. The Company considers these options in determining the lease term used to establish the right-of-use assets and lease liabilities. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based upon the information available at commencement date, or as of implementation of ASC 842, in determining the present value of lease payments.

Leases with an initial term of 12 months or less are not recorded on the balance sheet. We recognize lease expense for these leases on a straight-line basis over the lease term. Certain lease agreements contain both lease and non-lease components. We account for lease components together with non-lease components.

Operating lease cost was $15.3 million, $15.3 million and $16.6 for the years ended December 31, 2021 , December 31, 2020 and December 31, 2019, respectively. The components of lease costs are as follows:

		December 31,
(millions of dollars)	2021			2020			2019
Operating lease cost		$	15.2		$	15.2	$	15.5
Short-term lease cost			0.1			0.1		1.1
Total		$	15.3		$	15.3	$	16.6

Supplemental cash flow information and non-cash activity related to our leases are as follows:

(millions of dollars)	December 31, 2021

Operating cash flows information:
Cash paid for amounts included in the measurement of lease liabilities	$	16.0
Non-cash activity:
Right-of-use assets obtained in the exchange for operating lease liabilities	$	11.5

Weighted average remaining lease term, and weighted average discount rates related to the Company’s leases were as follows:

Weighted-average remaining operating lease term (in years)			7.22
Weighted-average operating leases discount rate			5.0	%

The following table summarizes the Company's outstanding lease assets and liabilities and their classification on the Consolidated Balance Sheet:

		December 31,
(millions of dollars)	Balance Sheet Classification	2021		2020

Right-of-use-asset	Other assets and deferred charges	$	49.6	$	50.9
Lease liability - current	Other current liabilities		11.7		11.7
Lease liability - non-current	Other non-current liabilities		47.2		49.2

Future minimum lease payments under the Company's leases as of December 31, 2021 were as follows:

(millions of dollars)	December 31, 2021

2022	$	14.3
2023		12.1
2024		9.5
2025		8.0
2026		7.4
Thereafter		19.3
Total future minimum lease payments		70.6
Less imputed interest		(11.7	)
Total	$	58.9

Revenue from Contracts with Customers

12 Months Ended

Dec. 31, 2021

Revenue from Contracts with Customers [Abstract]

Revenue from Contracts with Customers

Note 3. Revenue from Contracts with Customers

The Company’s revenues are primarily derived from the sale of products in product lines within our Performance Materials, Specialty Minerals and Refractories businesses.

On a regular basis, the Company reviews its segments and the approach used by the chief operating decision maker to assess performance and allocate resources. Accordingly, in the first quarter of 2021, the Company reorganized the management structure for its Energy Services and Performance Materials operating segments to support MTI's key growth initiatives, more closely align complementary technologies, processes and capabilities, and better reflect the way performance is evaluated and resources are allocated. As a result, Energy Services, was combined into the Environmental Products product line within the Performance Materials operating segment. The Performance Materials' operating segment restated financial results for the years ended 2020 and 2019, by product line, are presented in Note 21 to conform to the current management structure.

Our primary performance obligation (the sale of products) is satisfied upon shipment or delivery to our customers based on written sales terms, which is also when control is transferred. In most of our contracts in our Paper PCC product line, which is in our Specialty Minerals segment, the price per ton is based upon the total number of tons sold to the customer during the year. Under these contracts, the price billed to the customer for shipments during the year is based on periodic estimates of the total annual volume that will be sold to such customer. Revenues are adjusted at the end of each year to reflect the actual volume sold.

Revenue from sales of equipment, primarily in our Refractory products product line within our Refractories segment, is recorded upon completion of installation and control is transferred to the customer. Revenue from services is recorded when the services have been performed. Included within our Refractory products product line are certain consignment arrangements with certain customers in our Refractories segment. Revenues for these transactions are recorded when the consigned products are consumed by the customer and control is transferred.

Revenue where our performance obligations are satisfied in phases is recognized over time using certain input measures based on the measurement of the value transferred to the customer, including milestones achieved.

The following table disaggregates our revenue by major source (product line) for the years ended December 31, 2021, 2020 and 2019:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
Household, Personal Care & Specialty Products	$	460.5	$	380.2	$	376.6
Metalcasting		319.2		258.1		291.2
Environmental Products		136.3		131.6		181.8
Building Materials		60.0		55.9		68.9
Performance Materials		976.0		825.8		918.5

Paper PCC		349.7		308.4		364.9
Specialty PCC		77.1		69.3		69.1
Ground Calcium Carbonate		98.1		89.3		91.3
Talc		54.0		43.9		49.1
Specialty Minerals		578.9		510.9		574.4

Refractory Products		237.1		212.3		244.8
Metallurgical Products		66.3		45.8		53.3
Refractories		303.4		258.1		298.1

Total	$	1,858.3	$	1,594.8	$	1,791.0

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

+ Details

Acquisitions

12 Months Ended

Dec. 31, 2021

Acquisitions [Abstract]

Acquisitions

Note 4. Acquisitions

On July 26, 2021, the Company completed the acquisition of Normerica Inc., a leading North American supplier of premium pet care products for approximately $189 million. Normerica has production facilities in Canada, the U.S. and Thailand. As a leader in the pet product industry, Normerica provides premium products, both branded and private label to world-class retailers. Its product portfolio consists primarily of bentonite-based cat litter products which are supplied from a network of strategically located manufacturing facilities in Canada and the United States. The results of Normerica are included within our Household, Personal Care & Specialty Products product line in our Performance Materials segment. Normerica sales of $48.6 million are included in the Company's consolidated results for the year ended December 31, 2021. The acquisition was financed through a combination of cash on hand and the Company’s credit facilities. The fair value of the total consideration transferred, net of cash acquired, was $187.5 million.

The acquisition has been accounted for using the acquisition method of accounting, which requires, among other things, that we recognize the assets acquired and liabilities assumed at their respective fair values as of the acquisition date. As of December 31, 2021, the purchase price allocation remains preliminary as the Company completes its assessment of property, certain reserves, legal and tax matters, obligations, intangible assets and deferred taxes, as well as completes its review of Normerica’s existing accounting policies.

The following table summarizes the Company's preliminary purchase price allocation for the Normerica acquisition as compared with the allocation previously reported on the Company's Form 10-Q for the quarter ended October 3, 2021:

(millions of dollars)	Preliminary Allocation Previously Reported on Form 10-Q as of October 3, 2021		Increase/ (Decrease)			Preliminary Allocation as of December 31, 2021
Accounts receivable	$	8.4	$	—		$	8.4
Inventories		5.1		—			5.1
Other current assets		1.4		—			1.4
Property, plant and equipment		21.2		—			21.2
Goodwill		106.0		(1.5	)		104.5
Intangible assets		67.0		1.1			68.1
Total assets acquired		209.1		(0.4	)		208.7

Accounts payable		12.8		—			12.8
Accrued expenses		9.4		(1.0	)		8.4
Total liabilities assumed		22.2		(1.0	)		21.2
Net assets acquired	$	186.9	$	0.6		$	187.5

The Company used the income, market, or cost approach (or a combination thereof) for the preliminary valuation and used valuation inputs and analyses that were based on market participant assumptions. Changes in assumptions can have a significant impact on the fair value of intangible assets. Market participants are considered to be buyers and sellers unrelated to the Company in the principal or most advantageous market for the asset or liability. For certain items, the carrying value was determined to be a reasonable approximation of fair value based on the information available.

Goodwill was calculated as the excess of the consideration transferred over the assets acquired and represents the estimated future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. The goodwill is primarily attributable to fair value of expected synergies from combining the MTI and Normerica businesses and will be allocated to the Performance Materials reporting unit. The allocation is expected to be completed during the third quarter of 2022.

Intangible assets acquired of $68.1 million mainly include tradenames of $18.1 million and customer relationships of $50 million. Tradenames have an estimated useful life of approximately 15 years and customer relationships have an estimated useful life of approximately 20 years.

The Company did not present pro forma and other financial information for the Normerica acquisition, as this is not considered to be a material business combination.

The Company incurred $4.0 million and $3.1 million of acquisition-related costs during 2021 and 2020, respectively, which are reflected within the acquisition-related expenses line of the Consolidated Statements of Income.

In November 2021, the Company acquired Specialty PCC assets from a company in the Midwest United States for $6.9 million.

In the third quarter of 2020, the Company acquired the assets of a mining and hauling company in the western United States for $9.2 million to support our bentonite clay mining operations.

Restructuring and Other Items, net

12 Months Ended

Dec. 31, 2021

Restructuring and Other Items, net [Abstract]

Restructuring and Other Items, net

Note 5. Restructuring and Other Items, net

In the third quarter of 2021, PCA Corporation discontinued the use of PCC at their mill in Jackson, Alabama. As a result, the Company recorded a non-cash asset write-down of $0.7 million and $0.4 million in severance related and other closure costs for its Paper PCC satellite facility at this mill.

During the third quarter of 2020, Domtar Corporation announced the permanent shut down of their previously idled paper machine at their mill in Ashdown, Arkansas. As a result, the Company recorded a non-cash asset write-down charge of $1.1 million for its Paper PCC satellite facility at this mill.

During the second quarter of 2020, Verso Papers announced they would be idling two of their paper mills indefinitely. As a result, the Company recorded a non-cash asset write-down charge of $6.0 million and $0.3 million in severance related costs for its Paper PCC satellite facilities at these mills. The Company also recorded lease termination costs at one of these closed mills.

During the second quarter of 2019, the Company initiated a restructuring and cost savings program to better align our costs and organizational structure with the current market environment. The Company recorded a $7.5 million non-cash asset write-down charge related to facilities and equipment no longer operating and deemed to be held for sale or discontinued and $5.7 million in other restructuring costs.

The following table outlines the amount of restructuring charges recorded within the Consolidated Statements of Income and the segments they relate to:

Restructuring and Other Items, net	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Asset Write-Downs
Performance Materials	$	—	$	—	$	5.9
Specialty Minerals		0.7		7.1		1.6
Total asset write-down charges	$	0.7	$	7.1	$	7.5

Severance and other costs
Performance Materials	$	—	$	—	$	2.9
Specialty Minerals		0.4		0.5		0.9
Refractories		—		—		0.8
Corporate		—		—		1.1
Total severance and other employee costs	$	0.4	$	0.5	$	5.7

Total restructuring and other items, net	$	1.1	$	7.6	$	13.2

At December 31, 2021 and 2020, the Company had $2.2 million and $3.6 million, respectively, included within other current liabilities within our Consolidated Balance Sheets for cash expenditures needed to satisfy remaining obligations under these reorganization initiatives. The Company expects to pay these amounts by the end of 2022.

The following table is a reconciliation of our restructuring liability balance as of December 31, 2021 and 2020:

	December 31,
(millions of dollars)	2021			2020
Restructuring liability, beginning of period	$	3.6		$	5.0
Additional provisions		0.1			0.3
Cash payments		(1.5	)		(1.6	)
Other		—			(0.1	)
Restructuring liability, end of period	$	2.2		$	3.6

Stock-Based Compensation

12 Months Ended

Dec. 31, 2021

Stock-Based Compensation [Abstract]

Stock-Based Compensation

Note 6. Stock-Based Compensation

The Company’s 2015 Stock Award and Incentive Plan provides for grants of incentive and non-qualified stock options, restricted stock, stock appreciation rights, stock awards and performance unit awards (the 2015 Stock Award and Incentive Plan, as amended, referred to herein as the “Plan” and together with its predecessor for awards granted prior to May 2015, the 2001 Stock Award and Incentive Plan, as amended and restated, the “Plans”). The Plans are administered by the Compensation Committee of the Board of Directors. Stock options granted under the Plans generally have a ten year term. The exercise price for stock options are at prices at or above the fair market value of the common stock on the date of the grant, and each award of stock options will vest ratably over a specified period, generally three years.

Stock-based compensation expense is recognized in the consolidated financial statements for stock options based on the grant date fair value.

Net income for years ended 2021, 2020 and 2019 include $4.9 million, $4.6 million and $4.8 million pre-tax compensation costs, respectively, related to stock option expense as a component of marketing and administrative expenses. All stock option expense is recognized in the consolidated statements of operations. The related tax benefit included in the statement of income on the non-qualified stock options was $1.3 million, $1.2 million and $1.3 million for 2021, 2020 and 2019, respectively.

Stock Options

The fair value of options granted is estimated on the date of grant using the Black-Scholes valuation model. Compensation expense is recognized only for those options expected to vest, with forfeitures estimated at the date of grant based on the Company's historical experience and future expectations. The forfeiture rate assumption used for the periods ended December 31, 2021, 2020 and 2019 was 8.38%, 8.45% and 8.85%, respectively.

The weighted average grant date fair value for stock options granted during the years ended December 31, 2021, 2020 and 2019 was $21.62, $18.99 and $18.86, respectively. The weighted average grant date fair value for stock options vested during 2021, 2020 and 2019 was $20.56, $23.85 and $22.46, respectively. The total intrinsic value of stock options exercised during the years ended December 31, 2021, 2020 and 2019 was $6.1 million, $2.3 million and $2.2 million, respectively.

The fair value for stock awards was estimated at the date of grant using the Black-Scholes option valuation model with the following weighted average assumptions for the years ended December 31, 2021, 2020 and 2019:

	Year Ended December 31,
	2021			2020			2019
Expected life (in years)		6.9			6.7			6.6
Interest rate		0.71	%		1.67	%		2.62	%
Volatility		32.04	%		30.34	%		30.26	%
Expected dividend yield		0.31	%		0.35	%		0.37	%

The expected term of the options represents the estimated period of time until exercised and is based on historical experience of similar awards, based upon contractual terms, vesting schedules, and expectations of future employee behavior. The expected stock-price volatility is based upon the historical and implied volatility of the Company's stock. The interest rate is based upon the implied yield on U.S. Treasury bills with an equivalent remaining term. Estimated dividend yield is based upon historical dividends paid by the Company.

The following table summarizes stock option activity for the year ended December 31, 2021:

	Awards			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value (Millions)
Awards outstanding at December 31, 2020		1,363,366		$	57.29
Granted		255,769			66.00
Exercised		(251,195	)		51.12
Canceled		(37,938	)		64.92
Awards outstanding at December 31, 2021		1,330,002		$	59.91		6.14		$	18.7
Awards exercisable at December 31, 2021		834,060		$	59.09		4.80		$	12.8

The aggregate intrinsic value above is calculated before applicable income taxes, based on the Company's closing stock price of $73.15 as of the last business day of the period ended December 31, 2021 had all options been exercised on that date. The weighted average intrinsic value of the options exercised during 2021, 2020 and 2019 was $24.43, $24.41 and $27.21 per share, respectively. As of December 31, 2021, total unrecognized stock-based compensation expense related to non-vested stock options was approximately $4.9 million, which is expected to be recognized over a weighted average period of approximately three years.

The Company issues new shares of common stock upon the exercise of stock options.

Non-vested stock option activity for the year ended December 31, 2021 is as follows:

	Awards			Weighted Average Grant Date Fair Value per Share
Nonvested awards outstanding at December 31, 2020		487,160		$	58.61
Granted		255,769			66.00
Vested		(225,402	)		60.88
Canceled		(21,585	)		61.11
Nonvested awards outstanding at December 31, 2021		495,942		$	61.28

Restricted Stock

The Company has granted key employees rights to receive shares of the Company's common stock pursuant to the Plan. The rights will be deferred for a specified number of years of service, subject to restrictions on transfer and other conditions. Compensation expense for these shares is recognized over the vesting period. The Company granted 102,309 shares, 108,212 shares and 116,901 shares for the periods ended December 31, 2021, 2020 and 2019, respectively. The fair value was determined based on the market value of unrestricted shares. As of December 31, 2021, there was unrecognized stock-based compensation related to restricted stock of $6.4 million, which will be recognized over approximately the next three years. The compensation expense amortized with respect to all units was approximately $5.9 million, $5.6 million and $5.2 million for the periods ended December 31, 2021, 2020 and 2019, respectively. In addition, the Company recorded reversals of $2.6 million, $2.3 million and $1.9 million for periods ended December 31, 2021, 2020 and 2019, respectively, related mostly to the conversion of restricted stock for tax withholding purposes. Such costs and reversals are included in marketing and administrative expenses.

The following table summarizes the restricted stock activity for the Plan:

	Awards			Weighted Average Grant Date Fair Value per Share
Unvested balance at December 31, 2020		201,985		$	58.07
Granted		102,309			66.20
Vested		(51,497	)		60.40
Canceled		(56,664	)		60.98
Unvested balance at December 31, 2021		196,133		$	60.87

Earnings Per Share

12 Months Ended

Dec. 31, 2021

Earnings per Share [Abstract]

Earnings per Share (EPS)

Note 7. Earnings Per Share (EPS)

	Year Ended December 31,
(in millions, except per share data)	2021		2020		2019
Net income attributable to MTI	$	164.4	$	112.4	$	132.7


Weighted average shares outstanding		33.6		34.2		35.0
Dilutive effect of stock options and stock units		0.2		—		0.1
Weighted average shares outstanding, adjusted		33.8		34.2		35.1

Basic earnings per share attributable to MTI	$	4.89	$	3.29	$	3.79

Diluted earnings per share attributable to MTI	$	4.86	$	3.29	$	3.78

Of the options outstanding of 1,330,002, 1,363,366 and 1,227,620 for the years ended December 31, 2021, 2020 and 2019, respectively, options to purchase 510,683 shares, 591,322 shares and 825,331 shares of common stock for the years ended December 31, 2021, 2020 and 2019, respectively, were not included in the computation of diluted earnings per share because they were anti-dilutive, as the exercise prices of the options were greater than the average market price of the common shares.

Income Taxes

12 Months Ended

Dec. 31, 2021

Income Taxes [Abstract]

Income Taxes

Note 8. Income Taxes

Income from operations before provision for taxes by domestic and foreign source is as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Income from operations before income taxes and income from affiliates and joint ventures:
Domestic	$	66.0	$	21.4	$	46.9
Foreign		136.3		116.6		110.4
	$	202.3	$	138.0	$	157.3

The provision (benefit) for taxes on income consists of the following:

	Year Ended December 31,
(millions of dollars)	2021			2020			2019
Domestic
Taxes currently payable
Federal	$	(5.3	)	$	(7.1	)	$	(3.3	)
State and local		0.4			0.2			0.8
Deferred income taxes		7.8			2.2			(6.6	)
Domestic tax provision (benefit)		2.9			(4.7	)		(9.1	)

Foreign
Taxes currently payable		33.4			34.0			26.7
Deferred income taxes		0.3			(4.9	)		5.2
Foreign tax provision		33.7			29.1			31.9
Total tax provision (benefit)	$	36.6		$	24.4		$	22.8

The provision (benefit) for taxes on income shown in the previous table is classified based on the location of the taxing authority, regardless of the location in which the taxable income is generated.

The major elements contributing to the difference between the U.S. federal statutory tax rate and the consolidated effective tax rate are as follows:

	Year Ended December 31,
	2021			2020			2019
U.S. statutory rate		21.0	%		21.0	%		21.0	%

Depletion		(5.4	)%		(6.2	)%		(5.0	)%
Difference between tax provided on foreign earnings and the U.S. statutory rate		2.6	%		3.3	%		3.8	%
Global Intangible Low-Tax Income (GILTI)		0.7	%		0.4	%		—
Foreign Derived Intangible Income		(1.4	)%		(1.0	)%		(0.8	)%
State and local taxes, net of federal tax benefit		0.7	%		—			0.2	%
Tax credits and foreign dividends		(0.4	)%		(0.6	)%		(0.7	)%
Change in valuation allowance		—			—			1.0	%
Impact of uncertain tax positions		(1.1	)%		(0.2	)%		(5.0	)%
Impact of officer's non-deductible compensation		0.8	%		1.0	%		0.8	%
Impact of U.S. Tax Reform		—			—			(1.1	)%
Other		0.6	%		—			0.3	%
Consolidated effective tax rate		18.1	%		17.7	%		14.5	%

The Company believes that its accrued liabilities are sufficient to cover its U.S. and foreign tax contingencies. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities are presented below:

	December 31,
(millions of dollars)	2021			2020
Deferred tax assets attributable to:
Accrued liabilities	$	29.7		$	29.8
Net operating loss carry forwards		31.8			31.1
Pension and post-retirement benefits costs		31.4			46.3
Other		22.4			28.2
Valuation allowance		(22.3	)		(20.9	)
Total deferred tax assets		93.0			114.5
Deferred tax liabilities attributable to:
Plant and equipment, principally due to differences in depreciation		178.8			169.5
Intangible assets		69.3			69.5
Other		10.0			13.9
Total deferred tax liabilities		258.1			252.9
Net deferred tax asset (liability)	$	(165.1	)	$	(138.4	)

Net deferred tax assets and net deferred tax liabilities are as follows:

	December 31,
(millions of dollars)	2021				2020
Net deferred tax asset, long-term		$	23.0			$	25.3
Net deferred tax liability, long-term			188.1				163.7
Net deferred tax asset (liability), long-term		$	(165.1	)		$	(138.4	)

The Company has $31.8 million of deferred tax assets arising from tax loss carry forwards which will be realized through future operations. Carry forwards of approximately $17.8 million expire over the next 20 years, and $14.0 million can be utilized over an indefinite period.

On December 31, 2021, the Company had $5.1 million of total unrecognized tax benefits. Included in this amount were a total of $3.6 million of unrecognized income tax benefits that, if recognized, would affect the Company's effective tax rate. While it is expected that the amount of unrecognized tax benefits will change in the next 12 months, we do not expect the change to have a significant impact on the results of operations or the financial position of the Company.

The following table summarizes the activity related to our unrecognized tax benefits:

(millions of dollars)	2021			2020
Balance at beginning of the year	$	7.6		$	7.9
Increases related to current year tax positions		0.6			0.7
Increases related to new judgements		0.2			—
Decreases related to audit settlements and statue expirations		(3.3	)		(1.0	)

Balance at the end of the year	$	5.1		$	7.6

The Company's accounting policy is to recognize interest and penalties accrued, relating to unrecognized income tax benefits as part of its provision for income taxes. The Company recorded $0.8 million in interest and penalties during 2021 and had a total accrued balance on December 31, 2021 of $1.2 million.

The Company operates in multiple taxing jurisdictions, both within and outside the U.S. In certain situations, a taxing authority may challenge positions that the Company has adopted in its income tax filings. The Company, with a few exceptions (none of which are material), is no longer subject to U.S. federal, state, local, and international income tax examinations by tax authorities for years prior to 2015.

Net cash paid for income taxes were $42.5 million, $28.5 million and $29.5 million for the years ended December 31, 2021, 2020 and 2019, respectively.

The Company had approximately $481.4 million of foreign subsidiaries' undistributed earnings as of December 31, 2021. We intend to continue to permanently reinvest these earnings overseas for the foreseeable future and while U.S. federal tax expense has been recognized as a result of U.S. Tax Reform, no deferred tax liabilities with respect to foreign withholding taxes or state taxes have been recognized.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI http://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Inventories

12 Months Ended

Dec. 31, 2021

Inventories [Abstract]

Inventories

Note 9. Inventories

The following is a summary of inventories by major category:

	December 31,
(millions of dollars)	2021		2020
Raw materials	$	136.6	$	107.1
Work-in-process		10.7		9.0
Finished goods		99.4		85.6
Packaging and supplies		51.0		46.5
Total inventories	$	297.7	$	248.2

Property, Plant and Equipment

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Note 10. Property, Plant and Equipment

The major categories of property, plant and equipment and accumulated depreciation and depletion are presented below:

	December 31,
(millions of dollars)	2021			2020
Mineral rights and reserves	$	554.7		$	565.8
Land		50.6			50.9
Buildings		229.2			225.6
Machinery and equipment		1,262.8			1,254.3
Furniture and fixtures and other		139.9			138.9
Construction in progress		59.2			41.4
		2,296.4			2,276.9
Less: accumulated depreciation and depletion		(1,247.3	)		(1,237.3	)
Property, plant and equipment, net	$	1,049.1		$	1,039.6

In November 2021, the Company acquired Specialty PCC assets from a company in the Midwest United States for $6.9 million.

In the third quarter of 2020, the Company acquired the assets of a mining and hauling company in the western United States for $9.2 million to support our bentonite clay mining operations.

Depreciation and depletion expense for the years ended December 31, 2021, 2020 and 2019 was $77.4 million, $77.9 million and $82.1 million, respectively.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2021

Goodwill and Other Intangible Assets [Abstract]

Goodwill and Other Intangible Assets

Note 11. Goodwill and Other Intangible Assets

Goodwill and other intangible assets with indefinite lives are not amortized, but instead are assessed for impairment, at least annually. The carrying amount of goodwill was $907.5 million and $808.5 million as of December 31, 2021 and December 31, 2020, respectively. The net change in goodwill since December 31, 2021 was attributable to the acquisition of Normerica (see Note 4 to the Consolidated Financial Statements) and the effects to foreign exchange.

The balance of goodwill by segment and the activity occurring in the past two fiscal years is as follows:

(millions of dollars)	Performance Materials			Specialty Minerals			Refractories			Consolidated
Balance at December 31, 2019	$	751.2		$	12.5		$	43.7		$	807.4

Change in goodwill relating to:
Foreign exchange translation		1.2			0.2			(0.3	)		1.1
Total Changes	$	1.2		$	0.2		$	(0.3	)	$	1.1

Balance at December 31, 2020	$	752.4		$	12.7		$	43.4		$	808.5

Change in goodwill relating to:
Normerica acquisition		104.5			—			—			104.5
Foreign exchange translation		(3.9	)		(0.1	)		(1.5	)		(5.5	)
Total Changes	$	100.6		$	(0.1	)	$	(1.5	)	$	99.0

Balance at December 31, 2021	$	853.0		$	12.6		$	41.9		$	907.5

Acquired intangible assets subject to amortization as of December 31, 2021 and December 31, 2020 were as follows:

			December 31, 2021				December 31, 2020
	Weighted Average Useful Life (Years)		Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Tradenames		34	$	221.6	$	44.9	$	203.9	$	38.6
Technology		13		18.8		11.2		18.8		9.6
Patents and trademarks		19		6.4		6.4		6.4		6.1
Customer relationships		21		75.2		7.9		26.9		5.9
		29	$	322.0	$	70.4	$	256.0	$	60.2

The weighted average amortization period of the acquired intangible assets subject to amortization is approximately 29 years. Amortization expense was approximately $10.6 million, $9.3 million and $9.1 million for the years ended December 31, 2021, 2020 and 2019, respectively and is recorded within the Marketing and administrative expenses line within the Consolidated Statements of Income. The estimated amortization expense is as follows: 2022 - $12.7 million; 2023 -$12.6; 2024 - $12.6; 2025 -$12.6 million; 2026 - $12.6 million and $188.3 million thereafter.

Derivative Financial Instruments and Hedging Activities	12 Months Ended
Derivative Financial Instruments and Hedging Activities	Dec. 31, 2021
Derivative Financial Instruments and Hedging Activities [Abstract]
Derivative Financial Instruments and Hedging Activities	Note 12. Derivative Financial Instruments and Hedging Activities As a multinational corporation with operations throughout the world, the Company is exposed to certain market risks. The Company uses a variety of practices to manage these market risks, including, when considered appropriate, derivative financial instruments. The Company's objective is to offset gains and losses resulting from interest rates and foreign currency exposures with gains and losses on the derivative contracts used to hedge them. The Company uses derivative financial instruments only for risk management and not for trading or speculative purposes. By using derivative financial instruments to hedge exposures to changes in interest rates and foreign currencies, the Company exposes itself to credit risk and market risk. Credit risk is the risk that the counterparty will fail to perform under the terms of the derivative contract. When the fair value of a derivative contract is positive, the counterparty owes the Company, which creates credit risk for the Company. When the fair value of a derivative contract is negative, the Company owes the counterparty, and therefore, it does not face any credit risk. The Company minimizes the credit risk in derivative instruments by entering into transactions with major financial institutions. Market risk is the adverse effect on the value of a financial instrument that results from a change in interest rates, currency exchange rates, or commodity prices. The market risk associated with interest rate and forward exchange contracts is managed by establishing and monitoring parameters that limit the types and degree of market risk that may be undertaken. Cash Flow Hedges For derivative instruments that are designated and qualify as cash flow hedges, the Company records the effective portion of the gain or loss in accumulated other comprehensive income (loss) as a separate component of shareholders' equity. The Company subsequently reclassifies the effective portion of gain or loss into earnings in the period during which the hedged transaction is recognized in earnings. The Company utilizes interest rate swaps to limit exposure to market fluctuations on floating-rate debt. In the second quarter of 2018, the Company entered into a floating to fixed interest rate swap for a notional amount of $150 million. The fair value of this swap is a liability of $4.0 million at December 31, 2021 and is recorded in other non-current liabilities on the Consolidated Balance Sheet. This interest rate swap is designated as a cash flow hedge. As a result, the gains and losses associated with this interest rate swap is recorded in accumulated other comprehensive income (loss). Net Investment Hedges To protect the value of our investments in our foreign operations against adverse changes in foreign currency exchange rates, the Company from time to time hedges a portion of our net investment in one or more of our foreign subsidiaries. During the second quarter of 2018, the Company entered into a cross currency rate swap with a total notional value of $150 million to exchange monthly fixed-rate interest payments in U.S. dollars for monthly fixed-rate interest rate payments in Euros. This contract matures in May 2023 and requires the exchange of Euros and U.S. dollar principal payments upon maturity. The fair value of this swap is an asset of $8.2 million at December 31, 2021 and is recorded in other assets and deferred charges on the Consolidated Balance Sheet. Changes in the fair value of this instrument are recognized in accumulated other comprehensive income (loss) to offset the change in the carrying amount of the net investment being hedged. Amounts are reclassified out of accumulated other comprehensive income (loss) into earnings when the hedged net investment is either sold or substantially liquidated. Other The Company is exposed to potential gains or losses from foreign currency fluctuations affecting net investments and earnings denominated in foreign currencies. The Company is particularly sensitive to currency exchange rate fluctuations for the following currencies: British pound sterling (GBP), Chinese renminbi (CNY), Euro, Malaysian ringgit (MYR), Polish zloty (PLN), South African Rand (ZAR), Thai baht (THB) and Turkish lira (TRY). When considered appropriate, the Company enters into foreign exchange derivative contracts to mitigate the risk of fluctuations on these exposures. The Company does not designate these contracts for hedge accounting treatment and the changes in fair value of these contracts are recorded in earnings. The Company recorded losses (gains) of $0.7 million, $0.2 million and $2.1 million in other non-operating income (deductions), net within the Consolidated Statements of Income for the years ended 2021, 2020 and 2019 respectively. There were no open contracts at December 31, 2021 and December 31, 2020.

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2021

Fair Value of Financial Instruments [Abstract]

Fair Value of Financial Instruments

Note 13. Fair Value of Financial Instruments

Fair value is an exchange price that would be received for an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. The Company utilizes market data or assumptions that market participants would use in pricing the asset or liability. The Company follows a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs about which little or no market data exists, therefore requiring an entity to develop its own assumptions.

Assets and liabilities measured at fair value are based on one or more of three valuation techniques. The three valuation techniques are as follows:

●

Market approach – prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities.

●

Cost approach – amount that would be required to replace the service capacity of an asset or replacement cost.

●

Income approach – techniques to convert future amounts to a single present amount based on market expectations, including present value techniques, option-pricing and other models.

The Company primarily applies the income approach for foreign exchange derivatives for recurring fair value measurements and attempts to utilize valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs.

The following table sets forth by level within the fair value hierarchy the Company's financial assets and liabilities accounted for at fair value on a recurring basis at the end of each of the past two years. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels.

(millions of dollars)				Fair Value Measurements Using
	Asset / (Liability) Balance at			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs			Significant Unobservable Inputs
Description	December 31, 2021			(Level 1)		(Level 2)			(Level 3)
Deferred compensation plan assets	$	14.6		$	—	$	14.6		$	—

Supplementary pension plan assets		16.8			—		16.8			—

Cross currency rate swap		8.2			—		8.2			—

Interest rate swaps		(4.0	)		—		(4.0	)		—

				Fair Value Measurements Using
	Asset / (Liability) Balance at			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs			Significant Unobservable Inputs
Description	December 31, 2020			(Level 1)		(Level 2)			(Level 3)
Deferred compensation plan assets	$	14.2		$	—	$	14.2		$	—

Supplementary pension plan assets		15.0			—		15.0			—

Cross currency rate swap		0.4			—		0.4			—

Interest rate swaps		(7.6	)		—		(7.6	)		—

The fair value of foreign exchange contracts is determined based on inputs that are readily available in public markets or can be derived from information available in publicly quoted markets and are categorized as Level 2. Deferred compensation and supplementary pension plan assets related to the acquisition of AMCOL businesses and are valued using quoted prices for similar assets in active markets.

The Company does not have any financial assets or liabilities measured at fair value on a recurring basis categorized as Level 3, except for pension assets discussed in Note 16, and there were no transfers in or out of Level 3 during the year ended December 31, 2021 and 2020. There were also no changes to the Company's valuation techniques used to measure asset and liability fair values on a recurring basis.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Financial Instruments and Concentrations of Credit Risk	12 Months Ended
Financial Instruments and Concentrations of Credit Risk	Dec. 31, 2021
Financial Instruments and Concentrations of Credit Risk [Abstract]
Financial Instruments and Concentrations of Credit Risk	Note 14. Financial Instruments and Concentrations of Credit Risk The following methods and assumptions were used to estimate the fair value of each class of financial instrument: Cash and cash equivalents, short-term investments, accounts receivable and payable: The carrying amounts approximate fair value because of the short maturities of these instruments. Short-term debt and other liabilities: The carrying amounts of short-term debt and other liabilities approximate fair value because of the short maturities of these instruments. Long-term debt: The fair value of the long-term debt of the Company is estimated based on the quoted market prices for that debt or similar debt and approximates the carrying amount. Forward exchange contracts: The fair value of forward exchange contracts (used for hedging purposes) is based on information derived from active markets. If appropriate, the Company would enter into forward exchange contracts to mitigate the impact of foreign exchange rate movements on the Company's operating results. It does not engage in speculation. Such foreign exchange contracts would offset losses and gains on the assets, liabilities and transactions being hedged. Credit risk: The Company provides credit to customers in the ordinary course of business. The Company’s customer base is diverse and includes customers located throughout the world. Credit risk results from the possibility that a loss may occur from the failure of another party to perform according to the terms of the contracts. The Company regularly monitors its credit risk exposures and takes steps to mitigate the likelihood of these exposures resulting in an actual loss. The Company's extension of credit is based on an evaluation of the customer's financial condition and collateral is generally not required. The Company's bad debt expense for the years ended December 31, 2021, 2020 and 2019 was $0.9 million, $2.6 million and $6.3 million, respectively.

Long-Term Debt and Commitments

12 Months Ended

Dec. 31, 2021

Long-Term Debt and Commitments [Abstract]

Long-Term Debt and Commitments

Note 15. Long-Term Debt and Commitments

The following is a summary of long-term debt:

	December 31,
(millions of dollars)	2021		2020
Term Loan Facility- Variable Tranche due February 14, 2024, net of unamortized discount and deferred financing costs of $8.8 million and $12.4 million	$	539.2	$	535.6
Senior Notes due 2028, net of unamortized deferred financing costs of $5.4 million		394.6		393.9
Netherlands Term Loan due 2022		0.2		0.6
Japan Loan Facilities		3.0		4.1
Total	$	937.0	$	934.2
Less: Current maturities		0.8		1.0
Long-term debt	$	936.2	$	933.2

On May 9, 2014, in connection with the acquisition of AMCOL International Corporation (“AMCOL”), the Company entered into a credit agreement providing for a $1,560 million senior secured term loan facility (the “Term Facility”) and a $200 million senior secured revolving credit facility (the “Revolving Facility” and, together with the Term Facility, the “Facilities”).

On June 23, 2015, the Company entered into an amendment (the “First Amendment”) to the credit agreement to reprice the $1.378 billion then outstanding on the Term Facility. As amended, the Term Facility had a $1.078 billion floating rate tranche and a $300 million fixed rate tranche. On February 14, 2017, the Company entered into an amendment (the “Second Amendment”) to the credit agreement to reprice the $788 million floating rate tranche then outstanding, which extended the maturity and lowered the interest costs by 75 basis points. On April 18, 2018, the Company entered into an amendment (the “Third Amendment”) to the credit agreement to refinance its then existing senior secured revolving credit facility. In connection with the Third Amendment, the existing senior secured revolving credit facility was replaced with a new revolving credit facility with $300 million of aggregate commitments (the "Revolving Credit Facility" and, together with the Term Facility, the "Senior Secured Credit Facilities"). Following the amendments, the loans outstanding under the floating rate tranche of the Term Facility are scheduled to mature on February 14, 2024, and the loans outstanding (if any) and commitments under the Revolving Facility will mature and terminate, as the case may be, on April 18, 2023. Loans under the fixed rate tranche of the Term Facility were repaid in full in June 2020. Loans under the floating rate tranche of the Term Facility bear interest at a rate equal to an adjusted LIBOR rate (subject to a floor of 0.75%) plus an applicable margin equal to 2.25% per annum. Loans under the Revolving Facility bear interest at a rate equal to an adjusted LIBOR rate plus an applicable margin equal to 1.625% per annum. Such rates are subject to decrease by up to 25 basis points in the event that, and for so long as, the Company’s net leverage ratio (as defined in the credit agreement) is less than certain thresholds. The variable rate tranche has a 1% required amortization per year. The Company will pay certain fees under the credit agreement, including customary annual administration fees. The obligations of the Company under the Senior Secured Credit Facilities are unconditionally guaranteed jointly and severally by, subject to certain exceptions, all material domestic subsidiaries of the Company (the “Guarantors”) and secured, subject to certain exceptions, by a security interest in substantially all of the assets of the Company and the Guarantors.

The credit agreement contains certain customary affirmative and negative covenants that limit or restrict the ability of the Company and its restricted subsidiaries to enter into certain transactions or take certain actions. In addition, the credit agreement contains a financial covenant that requires the Company, if on the last day of any fiscal quarter loans or letters of credit were outstanding under the Revolving Facility (excluding up to $25 million of letters of credit), to maintain a maximum net leverage ratio (as defined in the credit agreement) of 3.50 to 1.00 for the four fiscal quarter period preceding such day. As of December 31, 2021, there were eighty outstanding loans and $10.6 million in letters of credit outstanding under the Revolving Facility. The Company is in compliance with all the covenants associated with the Revolving Facility as of the end of the period covered by this report.

On June 30, 2020, the Company issued $400 million aggregate principal amount of 5.0% Senior Notes due 2028 (the "Notes"). The Notes were issued pursuant to an indenture, dated as of June 30, 2020, between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee. The Company used the net proceeds of its offering of the Notes to repay all of its outstanding loans under the fixed rate tranche of the Term Facility, repay all of its outstanding borrowings under its Revolving Credit Facility, and the remainder for general corporate purposes.

The Notes bear an interest rate of 5.0% per annum payable semi-annually on January 1 and July 1 of each year, beginning on January 1, 2021. The Notes are unconditionally guaranteed on a senior unsecured basis by each of the Company's existing and future wholly owned domestic restricted subsidiaries that is a borrower under or that guarantees the Company's obligations under its Senior Secured Credit Facilities or that guarantees the Company's or any of the Company's wholly owned domestic subsidiaries' long-term indebtedness in an aggregate amount in excess of $50 million.

At any time and from time to time prior to July 1, 2023, the Company may redeem some or all of the Notes for cash at a redemption price equal to 100% of their principal amount, plus the “make-whole” premium described in the Indenture and accrued and unpaid interest, if any, to, but excluding, the applicable redemption date. Beginning on July 1, 2023, the Company may redeem some or all of the Notes at any time and from time to time at the applicable redemption prices listed in the Indenture, plus accrued and unpaid interest, if any, to, but excluding, the applicable redemption date. In addition, at any time and from time to time prior to July 1, 2023, the Company may redeem up to 40% of the aggregate principal amount of the Notes with funds from one or more equity offerings at a redemption price equal to 105% of the principal amount thereof, plus accrued and unpaid interest, if any, to, but excluding, the applicable redemption date.

If the Company experiences a change of control (as defined in the indenture), the Company is required to offer to repurchase the Notes at 101% of the principal amount of such Notes, plus accrued and unpaid interest, if any, to, but excluding, the date of repurchase.

The indenture contains certain customary affirmative and negative covenants that limit or restrict the ability of the Company and its restricted subsidiaries to enter into certain transactions or take certain actions, as well as customary events of default.

As part of the Company's acquisition of Sivomatic, the Company assumed $10.7 million in long-term debt, recorded at fair value, consisting of two term loans, one of which matured in the third quarter of 2020 and the other of which matures in 2022. The outstanding loan carries an interest rate of Euribor plus 2.0% and has quarterly repayments. During 2021, the Company repaid $0.4 million on this loan.

The Company has a committed loan facility in Japan. As of December 31, 2021, there was an outstanding balance of $3.0 million on this facility. Principal will be repaid in accordance with the payment schedules ending in 2021. The Company repaid $0.8 million on this loan in 2021.

As of December 31, 2021, the Company had $25.9 million in uncommitted short-term bank credit lines, none of which were in use.

There were $80.0 million and no short-term borrowings as of December 31, 2021 and 2020, respectively. The weighted average interest rate on short-term borrowings outstanding as December 31, 2021 was 1.8%.

The aggregate maturities of long-term debt are as follows: $0.8 million in 2022; $0.6 million in 2023; $548.6 million in 2024, $0.6 million in 2025; $0.6 million in 2026 and $400.0 million thereafter.

During 2021, 2020 and 2019, respectively, the Company incurred interest costs of $42.1 million, $40.7 million and $46.0 million, including $1.5 million, $0.6 million and $0.6 million, respectively, which were capitalized. Interest paid approximated the incurred interest cost.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI http://asc.fasb.org/topic&trid=2208564

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (h)
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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-Subparagraph (SX 210.4-08(c))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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+ Details

Benefit Plans

12 Months Ended

Dec. 31, 2021

Benefit Plans [Abstract]

Benefit Plans

Note 16. Benefit Plans

Pension Plans and Other Postretirement Benefit Plans

The Company and its subsidiaries have pension plans covering the majority of eligible employees on a contributory or non-contributory basis. Benefits under defined benefit plans are generally based on years of service and an employee's career earnings. Employees generally become fully vested after five years.

The Company also provides postretirement health care and life insurance benefits for the majority of its U.S. retired employees. Employees are generally eligible for benefits upon retirement and completion of a specified number of years of creditable service. The Company does not pre-fund these benefits and has the right to modify or terminate the plan in the future.

The Company’s disclosures for the U.S. plans have been combined with those outside of the U.S. as the international plans do not have significantly different assumptions, and together represent less than 22% of our total benefit obligation.

The following table set forth Company's pension obligation and funded status at December 31:

	Pension Benefits						Post-Retirement Benefits
(millions of dollars)	2021			2020			2021			2020
Change in benefit obligations:
Beginning projected benefit obligation	$	534.3		$	484.4		$	4.6		$	5.9
Service cost		7.7			7.7			0.1			0.2
Interest cost		7.9			10.5			0.1			0.2
Actuarial (gain)/loss		(23.8	)		56.5			(0.3	)		(1.3	)
Benefits paid		(12.4	)		(12.3	)		(0.5	)		(0.4	)
Settlements		(16.3	)		(18.4	)		(1.6	)		—
Foreign exchange impact		(2.7	)		5.5			(0.1	)		—
Other		0.3			0.4			—			—
Ending projected benefit obligation		495.0			534.3			2.3			4.6

Change in plan assets:
Beginning fair value		358.2			340.0			—			—
Actual return on plan assets		44.0			31.1			—			—
Employer contributions		10.7			11.8			0.5			0.4
Plan participants' contributions		0.3			0.3			—			—
Benefits paid		(12.4	)		(12.2	)		(0.5	)		(0.4	)
Settlements		(17.1	)		(16.9	)		—			—
Foreign exchange impact		(2.3	)		4.1			—			—
Ending fair value		381.4			358.2			—			—

Funded status	$	(113.6	)	$	(176.1	)	$	(2.3	)	$	(4.6	)

Amounts recognized in the consolidated balance sheet consist of:

	Pension Benefits								Post-Retirement Benefits
(millions of dollars)	2021				2020				2021				2020
Current liability		$	(1.4	)		$	(1.4	)		$	(0.2	)		$	(0.3	)
Non-current liability			(112.2	)			(174.7	)			(2.1	)			(4.3	)
Recognized liability		$	(113.6	)		$	(176.1	)		$	(2.3	)		$	(4.6	)

The current portion of pension liabilities is included in accrued compensation and related items.

Amounts recognized in accumulated other comprehensive income, net of related tax effects, consist of:

	Pension Benefits						Post-Retirement Benefits
(millions of dollars)	2021			2020			2021				2020
Net actuarial (gain) loss		$	73.2		$	119.0		$	(3.7	)		$	(4.2	)
Prior service cost			0.1			0.1			—				—
Amount recognized end of year		$	73.3		$	119.1		$	(3.7	)		$	(4.2	)

The accumulated benefit obligation for all defined benefit pension plans was $408.7 million and $501.7 million at December 31, 2021 and 2020, respectively. The decrease in the Company's pension obligation for 2021 is primarily attributable to actuarial gains resulting from the increase in the discount rate. The accumulated benefit obligations and projected benefit obligations are in excess of the plan assets for each of the Company's defined benefit plans.

Changes in the Plan assets and benefit obligations recognized in other comprehensive income:

	Pension Benefits					Post-Retirement Benefits
(millions of dollars)	2021		2020			2021			2020
Current year actuarial gain (loss)	$	36.7	$	(29.6	)	$	0.1		$	0.9
Amortization of actuarial (gain) loss		9.0		10.5			(0.6	)		(0.5	)
Amortization of prior service credit (gain) loss		—		—			—			—
Total recognized in other comprehensive income	$	45.7	$	(19.1	)	$	(0.5	)	$	0.4

The components of net periodic benefit costs are as follows:

	Pension Benefits									Post-Retirement Benefits
(millions of dollars)	2021			2020			2019			2021			2020			2019
Service cost	$	7.7		$	7.7		$	6.8		$	0.1		$	0.2		$	0.2
Interest cost		7.9			10.5			14.0			0.1			0.2			0.2
Expected return on plan assets		(22.0	)		(20.1	)		(18.2	)		—			—			—
Amortization of prior service cost		—			—			—			—			—			—
Recognized net actuarial (gain) loss		12.1			13.9			10.1			(0.8	)		(0.9	)		(0.9	)
Settlement/curtailment (gain) loss		3.4			6.4			(0.1	)		(1.6	)		—			—
Net periodic benefit cost	$	9.1		$	18.4		$	12.6		$	(2.2	)	$	(0.5	)	$	(0.5	)

Unrecognized prior service cost is amortized over the average remaining service period of each active employee.

The Company's funding policy for U.S. plans generally is to contribute annually into trust funds at a rate that provides for future plan benefits and maintains appropriate funded percentages. Annual contributions to the U.S. qualified plans are at least sufficient to satisfy regulatory funding standards and are not more than the maximum amount deductible for income tax purposes. The funding policies for the international plans conform to local governmental and tax requirements. The plans' assets are invested primarily in stocks and bonds.

Additional Information

The weighted average assumptions used to determine net periodic benefit cost in the accounting for the pension benefit plans and other benefit plans for the years ended December 31, 2021, 2020 and 2019 are as follows:

	Year Ended December 31,
	2021			2020			2019
Discount rate		2.01	%		2.74	%		3.75	%
Expected return on plan assets		6.28	%		6.32	%		6.43	%
Rate of compensation increase		2.72	%		2.72	%		3.01	%
Interest crediting rate		2.25	%		3.75	%		2.57	%

The weighted average assumptions used to determine benefit obligations for the pension benefit plans and other benefit plans at December 31, 2021, 2020 and 2019 are as follows:

	Year Ended December 31,
	2021			2020			2019
Discount rate		2.42	%		2.01	%		2.75	%
Rate of compensation increase		2.74	%		2.98	%		2.99	%

For 2021, 2020 and 2019, the discount rate was based on a Citigroup yield curve of high quality corporate bonds with cash flows matching our plans' expected benefit payments. The expected return on plan assets is based on our asset allocation mix and our historical return, taking into account current and expected market conditions. The actual return on pension assets was approximately 12% in 2021, 9% in 2020 and 15% in 2019.

The Company maintains a self-funded health insurance plan for its retirees. This plan provided that the maximum health care cost trend rate would be 5%. Effective June 2010, the Company amended its plan to change the eligibility requirement for retirees and revised its plan so that increases in expected health care costs would be borne by the retiree. Effective January 1, 2022, the plan was closed to new retirees. Accordingly, a $1.6 million curtailment gains was recognized as part of net periodic pension cost for the year ended December 31, 2021.

Plan Assets

The Company's pension plan weighted average asset allocation percentages at December 31, 2021 and 2020 by asset category are as follows:

	December 31,
	2021			2020
Asset Category
Equity securities		54.2	%		55.8	%
Fixed income securities		30.6	%		27.8	%
Real estate		0.3	%		0.3	%
Other		14.9	%		16.1	%
Total		100.0	%		100.0	%

The Company's pension plan fair values at December 31, 2021 and 2020 by asset category are as follows:

	December 31,
(millions of dollars)	2021		2020
Asset Category
Equity securities	$	206.7	$	200.0
Fixed income securities		116.5		99.7
Real estate		1.0		1.0
Other		57.1		57.5
Total	$	381.3	$	358.2

The following table presents domestic and foreign pension plan assets information at December 31, 2021, 2020 and 2019 (the measurement date of pension plan assets):

	U.S. Plans									International Plans
(millions of dollars)	2021			2020			2019			2021			2020			2019
Fair value of plan assets		$	293.7		$	271.6		$	261.5		$	87.6		$	86.6		$	78.5

The following table summarizes our defined benefit pension plan assets measured at fair value as of December 31, 2021:

	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(millions of dollars)	(Level 1)		(Level 2)		(Level 3)		Total
Pension Assets Fair Value as of December 31, 2021
Equity securities
US equities	$	182.7	$	—	$	—	$	182.7
Non-US equities		24.0		—		—		24.0

Fixed income securities
Corporate debt instruments		96.4		20.1		—		116.5

Real estate and other
Real estate		—		—		1.0		1.0
Other		0.4		51.7		5.0		57.1

Total assets	$	303.5	$	71.8	$	6.0	$	381.3

The following table summarizes our defined benefit pension plan assets measured at fair value as of December 31, 2020:

	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(millions of dollars)	(Level 1)		(Level 2)		(Level 3)		Total
Pension Assets Fair Value as of December 31, 2020
Equity securities
US equities	$	182.0	$	—	$	—	$	182.0
Non-US equities		18.0		—		—		18.0

Fixed income securities
Corporate debt instruments		80.4		19.3		—		99.7

Real estate and other
Real estate		—		—		1.0		1.0
Other		0.3		49.9		7.3		57.5

Total assets	$	280.7	$	69.2	$	8.3	$	358.2

U.S. equities – This class included actively and passively managed common equity securities comprised primarily of large-capitalization stocks with value, core and growth strategies.

Non-U.S. equities – This class included actively managed common equity securities comprised primarily of international large-capitalization stocks.

Fixed income – This class included debt instruments issued by the US Treasury, and corporate debt instruments.

Real Estate and other – This class includes assets related to real estate and other assets such as insurance contracts.

Asset classified as Level 1 are valued using quoted prices on major stock exchange on which individual assets are traded. Our Level 2 assets are valued using net asset value. The net asset value is quoted on a private market that is not active; however, the unit price is based on the underlying investments that are traded on an active market. Our Level 3 assets are estimated at fair value based on the most recent financial information available for the underlying securities, which are not traded on active market, and represents significant unobservable input.

The following is a reconciliation of changes in fair value measurement of plan assets using significant unobservable inputs (Level 3):

(millions of dollars)
Beginning balance at December 31, 2019	$	21.0
Purchases, sales, settlements		—
Actual return on plan assets still held at reporting date		(12.8	)
Foreign exchange impact		0.1
Ending balance at December 31, 2020	$	8.3
Purchases, sales, settlements		—
Actual return on plan assets still held at reporting date		(2.3	)
Foreign exchange impact		-
Ending balance at December 31, 2021	$	6.0

There were no transfers in or out of Level 3 during the year ended December 31, 2021 and 2020.

Contributions

The Company expects to contribute $10.1 million to its pension plans and $0.5 million to its other post-retirement benefit plan in 2022.

Estimated Future Benefit Payments

The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid:

(millions of dollars)	Pension Benefits		Other Benefits
2022	$	24.1	$	0.2
2023	$	25.9	$	0.2
2024	$	26.3	$	0.2
2025	$	26.1	$	0.2
2026	$	26.6	$	0.2
2027-2031	$	130.0	$	0.8

Investment Strategies

The investment strategy for pension plan assets is to maintain a broadly diversified portfolio designed to both preserve and grow plan assets to meet future plan obligations. The Company's average rate of return on assets from inception through December 31, 2021 was approximately 10%. The Company’s assets are strategically allocated among equity, debt and other investments to achieve a diversification level that dampens fluctuations in investment returns. The Company’s long-term investment strategy is an investment portfolio mix of approximately 55%-65% in equity securities, 30%-35% in fixed income securities and 0%-15% in other securities.

Savings and Investment Plans

The Company maintains a voluntary Savings and Investment Plan (a 401(k) plan) for most non-union employees in the U.S. Within prescribed limits, the Company bases its contribution to the Savings and Investment Plan on employee contributions. The Company's contributions amounted to $5.3 million, $5.2 million and $5.4 million for the years ended December 31, 2021, 2020 and 2019, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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+ Details

Contingencies	12 Months Ended
Contingencies	Dec. 31, 2021
Contingencies [Abstract]
Contingencies	Note 17. Contingencies The Company is party to a number of lawsuits arising in the normal course of our business. Certain of the Company’s subsidiaries are among numerous defendants in a number of cases seeking damages for exposure to silica or to asbestos containing materials. Most of these claims do not provide adequate information to assess their merits, the likelihood that the Company will be found liable, or the magnitude of such liability, if any. We are unable to state an amount or range of amounts claimed in any of the lawsuits because state court pleading practices do not require identifying the amount of the claimed damage. The aggregate cost to the Company for the legal defense of these cases since inception continues to be insignificant. The majority of the costs of defense for these cases, excluding cases against our subsidiaries AMCOL International Corporation or American Colloid Company, which we acquired in 2014, are reimbursed by Pfizer Inc. pursuant to the terms of certain agreements entered into in connection with the Company’s initial public offering in 1992. The Company is entitled to indemnification, pursuant to agreement, for liabilities related to sales prior to the initial public offering. The Company has settled only one silica lawsuit, for a nominal amount, and no asbestos lawsuits to date (not including any that may have been settled by AMCOL or American Colloid prior to completion of the acquisition). At this time, management anticipates that the amount of the Company’s liability, if any, and the cost of defending such claims, will not have a material effect on its financial position or results of operations. The Company and its subsidiaries are not party to any other material pending legal proceedings, other than routine litigation incidental to their businesses.

Stockholders' Equity

12 Months Ended

Dec. 31, 2021

Stockholders' Equity [Abstract]

Stockholders' Equity

Note 18. Stockholders' Equity

Capital Stock

The Company's authorized capital stock consists of 100 million shares of common stock, par value $0.10 per share, of which 33,177,193 shares and 33,882,187 shares were outstanding at December 31, 2021 and 2020, respectively, and 1,000,000 shares of preferred stock, none of which were issued and outstanding.

Cash Dividends

Cash dividends of $6.8 million or $0.20 per common share were paid during 2021. In January 2022, a cash dividend of approximately $1.7 million or $0.05 per share, was declared, payable in the first quarter of 2022.

Stock Award and Incentive Plan

The following table summarizes stock option and restricted stock activity for the Plans:

				Stock Options					Restricted Shares
	Shares Available for Grant			Shares			Weighted Average Exercise Price per Share ($)		Shares			Weighted Average Exercise Price per Share ($)
Balance January 1, 2019		866,023			1,054,259		$	54.04		134,578		$	68.64
Granted		(388,162	)		271,261			54.44		116,901			54.51
Exercised/vested		—			(79,686	)		27.26		(40,776	)		60.79
Canceled		51,181			(18,214	)		66.93		(32,967	)		61.87
Balance December 31, 2019		529,042			1,227,620			55.83		177,736			62.40
Authorized		1,300,000			—			—		—			—
Granted		(394,290	)		286,078			57.67		108,212			56.93
Exercised/vested		—			(93,099	)		35.11		(43,702	)		66.07
Canceled		97,494			(57,233	)		63.92		(40,261	)		65.42
Balance December 31, 2020		1,532,246			1,363,366			57.29		201,985			58.07
Granted		(358,078	)		255,769			66.00		102,309			66.20
Exercised/vested		—			(251,195	)		51.12		(51,497	)		60.40
Canceled		94,602			(37,938	)		64.92		(56,664	)		60.98
Balance December 31, 2021		1,268,770			1,330,002		$	59.91		196,133		$	60.87

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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+ Details

Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2021

Accumulated Other Comprehensive Income (Loss) [Abstract]

Accumulated Other Comprehensive Income (Loss)

Note 19. Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive income (loss) at December 31 comprised of the following components:

	December 31,
(millions of dollars)	2021			2020
Cumulative foreign currency translation	$	(269.8	)	$	(190.8	)
Unrecognized pension costs (net of tax benefit of $21.4 in 2021 and $64.6 in 2020)		(69.6	)		(114.9	)
Unrealized gain (loss) on cash flow hedges (net of tax expense (benefit) of $3.0 in 2021 and $(3.1) in 2020)		5.8			(2.6	)
	$	(333.6	)	$	(308.3	)

The following table summarizes the changes in other comprehensive income (loss) by component:

	Year Ended December 31,
	2021									2020									2019
(millions of dollars)	Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount			Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount			Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount
Foreign currency translation adjustment	$	(78.9	)	$	—		$	(78.9	)	$	10.9		$	—		$	10.9		$	(29.9	)	$	—		$	(29.9	)

Pension plans:
Net actuarial gains (losses) and prior service costs arising during the period		49.3			(12.5	)		36.8			(37.9	)		9.2			(28.7	)		(30.6	)		7.4			(23.2	)
Amortization of net actuarial (gains) losses and prior service costs		11.3			(2.9	)		8.4			13.4			(3.4	)		10.0			9.4			(2.3	)		7.1

Unrealized gains (losses) on cash flow hedges		11.4			(3.0	)		8.4			(11.6	)		3.1			(8.5	)		0.3			(0.1	)		0.2

Total other comprehensive income (loss)	$	(6.9	)	$	(18.4	)	$	(25.3	)	$	(25.2	)	$	8.9		$	(16.3	)	$	(50.8	)	$	5.0		$	(45.8	)

The pre-tax amortization amounts of pension plans in the table above are included within the components of net periodic pension benefit costs (see Note 16) and the related tax amounts are included within provision (benefit) for taxes on income line within Consolidated Statements of Income.

Accounting for Asset Retirement Obligations

12 Months Ended

Dec. 31, 2021

Accounting for Asset Retirement Obligations [Abstract]

Accounting for Asset Retirement Obligations

Note 20. Accounting for Asset Retirement Obligations

The Company records asset retirement obligations in which the Company will be required to retire tangible long-lived assets. These are primarily related to its PCC satellite facilities and mining operations. The Company has also recorded the provisions related to conditional asset retirement obligations at its facilities. The Company has recorded asset retirement obligations at all of its facilities except where there are no contractual or legal obligations. The associated asset retirement costs are capitalized as part of the carrying amount of the long-lived asset.

The following is a reconciliation of asset retirement obligations as of December 31, 2021 and 2020:

	December 31,
(millions of dollars)	2021			2020
Asset retirement obligation, beginning of period	$	24.1		$	23.9
Accretion expense		1.9			2.3
Other		1.2			1.1
Payments		(2.3	)		(3.4	)
Foreign currency translation		(0.5	)		0.2
Asset retirement obligation, end of period	$	24.4		$	24.1

The Company mines various minerals using a surface mining process that requires the removal of overburden. In certain areas and under various governmental regulations, the Company is obligated to restore the land comprising each mining site to its original condition at the completion of the mining activity. This liability will be adjusted to reflect the passage of time, mining activities, and changes in estimated future cash outflows.

The current portion of the liability of approximately $0.7 million is included in other current liabilities and the long-term portion of the liability of approximately $23.7 million is included in other non-current liabilities in the Consolidated Balance Sheet as of December 31, 2021.

Accretion expense is included in cost of goods sold in the Company's Consolidated Statements of Income.

Segment and Related Information

12 Months Ended

Dec. 31, 2021

Segment and Related Information

Note 21. Segment and Related Information

The Company determines its operating segments based on the discrete financial information that is regularly evaluated by its chief operating decision maker, our Chief Executive Officer, in deciding how to allocate resources and in assessing performance. Accordingly, in the first quarter of 2021, the Company reorganized the management structure for its Energy Services and Performance Materials operating segments to support MTI's key growth initiatives, more closely align complementary technologies, processes and capabilities, and better reflect the way performance is evaluated and resources are allocated. As a result, Energy Services was combined into the Environmental Products product line within the Performance Materials operating segment. Presented below are the restated financial results for fiscal years ended 2020 and 2019 to conform to the current management structure.

The Company's operating segments are strategic business units that offer different products and serve different markets. They are managed separately and require different technology and marketing strategies.

The Company has three reportable segments: Performance Materials, Specialty Minerals and Refractories.

●

The Performance Materials segment is a leading global supplier of bentonite and bentonite-related products and leonardite. This segment also provides products for non-residential construction, environmental and infrastructure projects worldwide, serving customers engaged in a broad range of construction and remediation projects, as well as offers a range of patented and unpatented technologies, products and services to the upstream and downstream oil and gas sector throughout the world.

●

The Specialty Minerals segment produces and sells the synthetic mineral product precipitated calcium carbonate ("PCC") and processed mineral product quicklime ("lime"), and mines mineral ores then processes and sells natural mineral products, primarily limestone and talc.

●

The Refractories segment produces and markets monolithic and shaped refractory materials and specialty products, services and application and measurement equipment, and calcium metal and metallurgical wire products.

The accounting policies of the segments are the same as those described in the summary of significant accounting policies. The Company evaluates performance based on the operating income of the respective business units. The costs deducted to arrive at operating profit do not include several items, such as net interest or income tax expense. Depreciation expense related to corporate assets is allocated to the business segments and is included in their income from operations. However, such corporate depreciable assets are not included in the segment assets. Intersegment sales and transfers are not significant.

Segment information for the years ended December 31, 2021, 2020 and 2019 was as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
Performance Materials	$	976.0	$	825.8	$	918.5
Specialty Minerals		578.9		510.9		574.4
Refractories		303.4		258.1		298.1
Total		1,858.3		1,594.8		1,791.0

Income from Operations
Performance Materials		125.0		108.8		104.9
Specialty Minerals		72.9		67.8		83.1
Refractories		49.3		35.5		39.8
Total		247.2		212.1		227.8

Depreciation, Depletion and Amortization
Performance Materials		49.2		47.4		51.0
Specialty Minerals		38.4		39.6		40.4
Refractories		7.0		6.9		7.0
Total		94.6		93.9		98.4

Segment Assets
Performance Materials		2,393.2		2,219.1		2,212.7
Specialty Minerals		605.9		559.6		525.1
Refractories		293.1		290.8		293.2
Total		3,292.2		3,069.5		3,031.0

Capital Expenditures
Performance Materials		22.0		14.6		21.5
Specialty Minerals		51.7		46.5		37.7
Refractories		9.7		5.5		5.7
Total		83.4		66.6		64.9

A reconciliation of the totals reported for the operating segments to the applicable line items in the consolidated financial statements is as follows:

	Year Ended December 31,
(millions of dollars)	2021			2020			2019
Income from Operations before Provision for Taxes on Income
Income from operations for reportable segments	$	247.2		$	212.1		$	227.8
Litigation expenses		—			(10.4	)		(10.9	)
Acquisition-related expenses		(4.0	)		(3.1	)		—
Unallocated corporate expenses		(7.5	)		(10.7	)		(8.2	)
Consolidated income from operations		235.7			187.9			208.7
Non-operating deductions, net		(33.4	)		(49.9	)		(51.4	)
Income from operations before provision for taxes and equity in earnings		202.3			138.0			157.3

Total Assets
Total segment assets		3,292.2			3,069.5			3,031.0
Corporate assets		82.0			139.9			81.6
Consolidated total assets		3,374.2			3,209.4			3,112.6

Capital Expenditures
Total segment capital expenditures		83.4			66.6			64.9
Corporate capital expenditures		2.6			0.2			0.1
Consolidated capital expenditures		86.0			66.8			65.0

Financial information relating to the Company's operations by geographic area was as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
United States	$	959.6	$	822.5	$	962.4

Canada/Latin America		99.8		70.5		80.2
Europe/Africa		441.9		410.0		435.3
Asia		357.0		291.8		313.1
Total International		898.7		772.3		828.6
Consolidated net sales		1,858.3		1,594.8		1,791.0

Long-Lived Assets
United States	$	1,925.3	$	1,723.2	$	1,742.3

Canada/Latin America		10.6		11.3		13.0
Europe/Africa		151.1		182.9		190.7
Asia		120.6		126.5		117.2
Total International		282.3		320.7		320.9
Consolidated long-lived assets		2,207.6		2,043.9		2,063.2

Net sales and long-lived assets are attributed to countries and geographic areas based on the location of the legal entity. No individual foreign country represents more than 10% of consolidated net sales or consolidated long-lived assets.

The Company's sales by product category are as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Household, Personal Care & Specialty Products	$	460.5	$	380.2	$	376.6
Metalcasting		319.2		258.1		291.2
Environmental Products		136.3		131.6		181.8
Building Materials		60.0		55.9		68.9
Paper PCC		349.7		308.4		364.9
Specialty PCC		77.1		69.3		69.1
Ground Calcium Carbonate		98.1		89.3		91.3
Talc		54.0		43.9		49.1
Refractory Products		237.1		212.3		244.8
Metallurgical Products		66.3		45.8		53.3
Total	$	1,858.3	$	1,594.8	$	1,791.0

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

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+ Details

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2021

Schedule II - Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation and Qualifying Accounts

MINERALS TECHNOLOGIES INC. & SUBSIDIARY COMPANIES

SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS

(millions of dollars)

Description	Balance at Beginning of Period		Additions Charged to Costs, Provisions and Expenses		Deductions (a)			Balance at End of Period
Year Ended December 31, 2021
Valuation and qualifying accounts deducted from assets to which they apply:
Allowance for doubtful accounts	$	15.0		0.9		(0.9	)	$	15.0
Year Ended December 31, 2020
Valuation and qualifying accounts deducted from assets to which they apply:
Allowance for doubtful accounts	$	12.9		2.6		(0.5	)	$	15.0
Year Ended December 31, 2019
Valuation and qualifying accounts deducted from assets to which they apply:
Allowance for doubtful accounts	$	3.2		6.3		3.4		$	12.9

(a)	Includes impact of write-offs, translation of foreign currencies and reclassifications for presentation purposes.

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2021
Summary of Significant Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company, its wholly and majority-owned subsidiaries, as well as variable interest entities for which the Company is the primary beneficiary. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The Company employs accounting policies that are in accordance with U.S. generally accepted accounting principles and require management to make estimates and assumptions relating to the reporting of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reported period. Significant estimates include those related to revenue recognition, valuation of long-lived assets, goodwill and other intangible assets, pension plan assumptions, income tax, and litigation and environmental liabilities. Actual results could differ from those estimates.
Cash Equivalents and Short-term Investments	Cash Equivalents and Short-term Investments The Company considers all highly liquid investments with original maturities of three months or less to be cash equivalents. Short-term investments consist of financial instruments, mainly bank deposits, with original maturities beyond three months, but less than twelve months. Short-term investments amounted to $4.9 million and $4.1 million at December 31, 2021 and 2020, respectively. There were no unrealized holding gains and losses on the short-term bank investments held at December 31, 2021.
Trade Accounts Receivable	Trade Accounts Receivable Trade accounts receivables are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company's best estimate of the amount of probable credit losses in the Company's existing accounts receivable. The Company determines the allowance based on historical write-off experience and specific allowances for bankrupt customers. The Company also analyzes the collection history and financial condition of its other customers, considering current industry conditions and determines whether an allowance needs to be established. The Company reviews its allowance for doubtful accounts monthly. Past due balances over 90 days based on payment terms are reviewed individually for collectability. Allowance for doubtful accounts was $15.0 million at both December 31, 2021 and 2020. Account balances are charged off against the allowance after all means of collection have been exhausted and the potential for recovery is considered remote. The Company does not have any off-balance-sheet credit exposure related to its customers.
Inventories	Inventories Inventories are valued at the lower of cost or market. Cost is determined by the first-in, first-out (FIFO) method. Additionally, items such as idle facility expense, excessive spoilage, freight handling costs, and re-handling costs are recognized as current period charges. The allocation of fixed production overheads to the costs of conversion are based upon the normal capacity of the production facility. Fixed overhead costs associated with idle capacity are expensed as incurred.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost. Significant improvements are capitalized, while maintenance and repair expenditures are charged to operations as incurred. The Company capitalizes interest cost as a component of construction in progress. The straight-line method of depreciation is used for substantially all of the assets for financial reporting purposes, except for mining related equipment which uses units-of-production method. The annual rates of depreciation are 3% - 6.67% for buildings, 6.67% - 12.5% for machinery and equipment, 8% - 12.5% for furniture and fixtures and 12.5% - 25% for computer equipment and software-related assets. The estimated useful lives of our PCC production facilities and machinery and equipment pertaining to our natural stone mining and processing plants and our chemical plants are 15 years. Property, plant and equipment are depreciated over their useful lives. Useful lives are based on management's estimates of the period that the assets can generate revenue, which does not necessarily coincide with the remaining term of a customer's contractual obligation to purchase products made using those assets. The Company's sales of PCC are predominantly pursuant to long-term evergreen contracts, initially ten years in length, with paper mills at which the Company operates satellite PCC plants. The terms of many of these agreements have been extended, often in connection with an expansion of the satellite PCC plant. Failure of a PCC customer to renew an agreement or continue to purchase PCC from a Company facility could result in an impairment of assets charge or accelerated depreciation at such facility. Depletion of mineral reserves is determined on a unit-of-extraction basis for financial reporting purposes, based upon proven and probable reserves, and generally on a percentage depletion basis for tax purposes.
Stripping Costs Incurred During Production	Stripping Costs Incurred During Production Stripping costs are those costs incurred for the removal of waste materials for the purpose of accessing ore body that will be produced commercially. Stripping costs incurred during the production phase of a mine are variable costs that are included in the costs of inventory produced during the period that the stripping costs are incurred.
Accounting for the Impairment of Long-Lived Assets	Accounting for the Impairment of Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable, the Company estimates the undiscounted future cash flows (excluding interest), resulting from the use of the asset and its ultimate disposition. If the sum of the undiscounted cash flows (excluding interest) is less than the carrying value, the Company recognizes an impairment loss, measured as the amount by which the carrying value exceeds the fair value of the asset, determined principally using discounted cash flows.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill represents the excess of purchase price and related costs over the value assigned to the net tangible and identifiable intangible assets of businesses acquired. Goodwill is not amortized, but instead assessed for impairment. Intangible assets with estimable useful lives are amortized on a straight-line basis over their respective estimated lives to the estimated residual values, and reviewed for impairment. The Company performs a qualitative assessment for each of its reporting units to determine if the two-step process for impairment testing is required. If the Company determines that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, the Company would then evaluate the recoverability of goodwill using a two-step impairment test approach at the reporting unit level. In the first step, the fair value for the reporting unit is compared to its book value including goodwill. In the case that the fair value of the reporting unit is less than book value, a second step is performed which compares the fair value of the reporting unit's goodwill to the book value of the goodwill. The fair value for the goodwill is determined based on the difference between the fair values of the reporting unit and the net fair values of the identifiable assets and liabilities of such reporting unit. If the fair value of the goodwill is less than the book value, the difference is recognized as impairment. In addition to the assessment of goodwill impairment, the Company also reviews its other identifiable intangibles for impairment. Each year, the Company reviews whether events or changes in circumstances could indicate that a long-lived asset's carrying amount may not be recoverable. Should such events occur, the value of intangibles not recoverable would be recognized as impairment.
Investment in Joint Ventures	Investment in Joint Ventures The Company uses the equity method of accounting to incorporate the results of its investments in companies in which it has significant influence but does not control; and cost method of accounting in companies in which it cannot exercise significant control. The Company records the equity in earnings of its investments in joint ventures on a one-month lag. At December 31, 2021 and 2020, the book value of the Company’s equity method investments was $17.5 million and $17.0 million.
Accounting for Asset Retirement Obligations	Accounting for Asset Retirement Obligations The Company provides for obligations associated with the retirement of long-lived assets and the associated asset retirement costs. The fair value of a liability for an asset retirement obligation is recognized in the period in which it is incurred if a reasonable estimate of fair value can be made. The associated asset retirement costs are capitalized as part of the carrying amount of the long-lived asset. The Company also provides for legal obligations to perform asset retirement activities where timing or methods of settlement are conditional on future events. The Company also records liabilities related to land reclamation as a part of the asset retirement obligations. The Company mines land for various minerals using a surface-mining process that requires the removal of overburden. In many instances, the Company is obligated to restore the land upon completion of the mining activity. As the overburden is removed, the Company recognizes this liability for land reclamation based on the estimated fair value of the obligation. The obligation is adjusted to reflect the passage of time and changes in estimated future cash outflows.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The recorded amounts of cash and cash equivalents, receivables, short-term borrowings, accounts payable, accrued interest, and variable-rate long-term debt approximate fair value because of the short maturity of those instruments or the variable nature of underlying interest rates. Short-term investments are recorded at cost, which approximates fair market value.
Derivative Financial Instruments	Derivative Financial Instruments The Company records derivative financial instruments which are used to hedge certain foreign exchange risk at fair value on the balance sheet. See Note 12 for a full description of the Company's hedging activities and related accounting policies.
Revenue Recognition	Revenue Recognition Revenue is recognized at the point in time when the customer obtains control of the promised goods or services in an amount that reflects the consideration we expect to receive in exchange for those goods or services. The Company's revenues are primarily derived from the sale of products. Our primary performance obligation is satisfied upon shipment or delivery to our customer based on written sales terms, which is also when control is transferred. Revenues from sales of equipment are recorded upon completion of installation and transfer of control to the customer. Revenue where our performance obligations are satisfied in phases is recognized over time using certain input measures based on the measurement of the value transferred to the customer, including milestones achieved. Revenues from services are recorded when the services are performed. In most of our PCC contracts, the price per ton is based upon the total number of tons sold to the customer during the year. Under those contracts, the price billed to the customer for shipments during the year is based on periodic estimates of the total annual volume that will be sold to the customer. Revenues are adjusted at the end of each year to reflect the actual volume sold. There were no significant revenue adjustments in the fourth quarter of 2021 and 2020, respectively. We have consignment arrangements with certain customers in our Refractories segment. Revenues for these transactions are recorded when the consigned products are consumed by the customer.
Foreign Currency	Foreign Currency The assets and liabilities of the Company's international subsidiaries are translated into U.S. dollars using exchange rates at the respective balance sheet date. The resulting translation adjustments are recorded in accumulated other comprehensive income (loss) in shareholders' equity. Income statement items are generally translated at monthly average exchange rates prevailing during the period. International subsidiaries operating in highly inflationary economies translate non-monetary assets at historical rates, while net monetary assets are translated at current rates, with the resulting translation adjustments included in net income. At December 31, 2021, the Company had no international subsidiaries operating in highly inflationary economies.
Income Taxes	Income Taxes Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates in effect for the year in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. The Company operates in multiple taxing jurisdictions, both within the U.S. and outside the U.S. In certain situations, a taxing authority may challenge positions that the Company has adopted in its income tax filings. The Company regularly assesses its tax position for such transactions and includes reserves for those differences in position. The reserves are utilized or reversed once the statute of limitations has expired or the matter is otherwise resolved. The application of income tax law is inherently complex. Laws and regulations in this area are voluminous and are often ambiguous. As such, we are required to make many subjective assumptions and judgments regarding our income tax exposures. Interpretations of and guidance surrounding income tax laws and regulations change over time. As such, changes in our subjective assumptions and judgments can materially affect amounts recognized in the consolidated balance sheets and statements of operations. The Company's accounting policy is to recognize interest and penalties as part of its provision for income taxes. See Note 8 for additional detail on our uncertain tax positions. The accompanying financial statements do not include a provision for foreign withholding taxes on international subsidiaries' unremitted earnings, which are expected to be permanently reinvested overseas.
Research and Development	Research and Development Research and development costs are expensed as incurred.
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation The Company recognizes compensation expense for share-based awards based upon the grant date fair value over the vesting period.
Pension and Post-retirement Benefits	Pension and Post-retirement Benefits The Company has defined benefit pension plans covering the majority of its employees. The benefits are generally based on years of service and an employee's modified career earnings. The Company also provides post-retirement healthcare benefits for the majority of its retirees and employees in the United States. The Company measures the costs of its obligation based on its best estimate. The net periodic costs are recognized as employees render the services necessary to earn the post-retirement benefits.
Environmental	Environmental Expenditures that relate to current operations are expensed or capitalized as appropriate. Expenditures that relate to an existing condition caused by past operations and which do not contribute to current or future revenue generation are expensed. Liabilities are recorded when it is probable the Company will be obligated to pay amounts for environmental site evaluation, remediation or related costs, and such amounts can be reasonably estimated.
Earnings Per Share	Earnings Per Share Basic earnings per share have been computed based upon the weighted average number of common shares outstanding during the period. Diluted earnings per share have been computed based upon the weighted average number of common shares outstanding during the period assuming the issuance of common shares for all potentially dilutive common shares outstanding.
Subsequent Events	Subsequent Events The Company has evaluated for subsequent events through the date of issuance of its financial statements.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Changes to accounting principles generally accepted in the United States of America (U.S. GAAP) are established by the Financial Accounting Standards Board (FASB) in the form of accounting standards updates (ASUs) to the FASB’s Accounting Standards Codification. The Company considers the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on our consolidated financial position and results of operations. Adoption of Simplifying the Accounting for Income Taxes In December 2019, the FASB issued ASU 2019-12, "Simplifying the Accounting for Income Taxes", to simplify the accounting for income taxes and improve consistent application by clarifying or amending existing guidance. The Company adopted this guidance on January 1, 2021. Adoption of this standard did not have a material impact on the Company's consolidated financial statements. Adoption of Investments - Equity Securities, Investments - Equity Method and Joint Ventures, and Derivatives and Hedging In January 2020, the FASB issued ASU 2020-01, "Investments - Equity Securities, Investments - Equity Method and Joint Ventures, and Derivatives and Hedging", which addresses the accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. The Company adopted this guidance on January 1, 2021. Adoption of this standard did not have a material impact on the Company's consolidated financial statements.

Leases (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Components of Lease Cost

		December 31,
(millions of dollars)	2021			2020			2019
Operating lease cost		$	15.2		$	15.2	$	15.5
Short-term lease cost			0.1			0.1		1.1
Total		$	15.3		$	15.3	$	16.6

Supplemental Cash Flow Information and Non-cash Activity Related to Operating Leases

Supplemental cash flow information and non-cash activity related to our leases are as follows:

(millions of dollars)	December 31, 2021

Operating cash flows information:
Cash paid for amounts included in the measurement of lease liabilities	$	16.0
Non-cash activity:
Right-of-use assets obtained in the exchange for operating lease liabilities	$	11.5

Weighted Average Remaining Lease Term and Discount Rates

Weighted average remaining lease term, and weighted average discount rates related to the Company’s leases were as follows:

Weighted-average remaining operating lease term (in years)			7.22
Weighted-average operating leases discount rate			5.0	%

Outstanding Lease Assets and Liabilities

The following table summarizes the Company's outstanding lease assets and liabilities and their classification on the Consolidated Balance Sheet:

		December 31,
(millions of dollars)	Balance Sheet Classification	2021		2020

Right-of-use-asset	Other assets and deferred charges	$	49.6	$	50.9
Lease liability - current	Other current liabilities		11.7		11.7
Lease liability - non-current	Other non-current liabilities		47.2		49.2

Future Minimum Lease Payments

Future minimum lease payments under the Company's leases as of December 31, 2021 were as follows:

(millions of dollars)	December 31, 2021

2022	$	14.3
2023		12.1
2024		9.5
2025		8.0
2026		7.4
Thereafter		19.3
Total future minimum lease payments		70.6
Less imputed interest		(11.7	)
Total	$	58.9

Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2021

Revenue from Contracts with Customers [Abstract]

Disaggregation of Revenue

The following table disaggregates our revenue by major source (product line) for the years ended December 31, 2021, 2020 and 2019:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
Household, Personal Care & Specialty Products	$	460.5	$	380.2	$	376.6
Metalcasting		319.2		258.1		291.2
Environmental Products		136.3		131.6		181.8
Building Materials		60.0		55.9		68.9
Performance Materials		976.0		825.8		918.5

Paper PCC		349.7		308.4		364.9
Specialty PCC		77.1		69.3		69.1
Ground Calcium Carbonate		98.1		89.3		91.3
Talc		54.0		43.9		49.1
Specialty Minerals		578.9		510.9		574.4

Refractory Products		237.1		212.3		244.8
Metallurgical Products		66.3		45.8		53.3
Refractories		303.4		258.1		298.1

Total	$	1,858.3	$	1,594.8	$	1,791.0

Acquisitions (Tables)

12 Months Ended

Dec. 31, 2021

Acquisitions [Abstract]

Preliminary Purchase Price Allocation for Normerica Acquisition

(millions of dollars)	Preliminary Allocation Previously Reported on Form 10-Q as of October 3, 2021		Increase/ (Decrease)			Preliminary Allocation as of December 31, 2021
Accounts receivable	$	8.4	$	—		$	8.4
Inventories		5.1		—			5.1
Other current assets		1.4		—			1.4
Property, plant and equipment		21.2		—			21.2
Goodwill		106.0		(1.5	)		104.5
Intangible assets		67.0		1.1			68.1
Total assets acquired		209.1		(0.4	)		208.7

Accounts payable		12.8		—			12.8
Accrued expenses		9.4		(1.0	)		8.4
Total liabilities assumed		22.2		(1.0	)		21.2
Net assets acquired	$	186.9	$	0.6		$	187.5

Restructuring and Other Items, net (Tables)

12 Months Ended

Dec. 31, 2021

Restructuring and Other Items, net [Abstract]

Restructuring Charges by Segment

The following table outlines the amount of restructuring charges recorded within the Consolidated Statements of Income and the segments they relate to:

Restructuring and Other Items, net	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Asset Write-Downs
Performance Materials	$	—	$	—	$	5.9
Specialty Minerals		0.7		7.1		1.6
Total asset write-down charges	$	0.7	$	7.1	$	7.5

Severance and other costs
Performance Materials	$	—	$	—	$	2.9
Specialty Minerals		0.4		0.5		0.9
Refractories		—		—		0.8
Corporate		—		—		1.1
Total severance and other employee costs	$	0.4	$	0.5	$	5.7

Total restructuring and other items, net	$	1.1	$	7.6	$	13.2

Reconciliation of Restructuring Liability

The following table is a reconciliation of our restructuring liability balance as of December 31, 2021 and 2020:

	December 31,
(millions of dollars)	2021			2020
Restructuring liability, beginning of period	$	3.6		$	5.0
Additional provisions		0.1			0.3
Cash payments		(1.5	)		(1.6	)
Other		—			(0.1	)
Restructuring liability, end of period	$	2.2		$	3.6

Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Stock-Based Compensation [Abstract]

Weighted Average Assumptions Used to Determine Fair Value for Stock Awards

	Year Ended December 31,
	2021			2020			2019
Expected life (in years)		6.9			6.7			6.6
Interest rate		0.71	%		1.67	%		2.62	%
Volatility		32.04	%		30.34	%		30.26	%
Expected dividend yield		0.31	%		0.35	%		0.37	%

Stock Option Activity

The following table summarizes stock option activity for the year ended December 31, 2021:

	Awards			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value (Millions)
Awards outstanding at December 31, 2020		1,363,366		$	57.29
Granted		255,769			66.00
Exercised		(251,195	)		51.12
Canceled		(37,938	)		64.92
Awards outstanding at December 31, 2021		1,330,002		$	59.91		6.14		$	18.7
Awards exercisable at December 31, 2021		834,060		$	59.09		4.80		$	12.8

Non-vested Stock Option Activity

Non-vested stock option activity for the year ended December 31, 2021 is as follows:

	Awards			Weighted Average Grant Date Fair Value per Share
Nonvested awards outstanding at December 31, 2020		487,160		$	58.61
Granted		255,769			66.00
Vested		(225,402	)		60.88
Canceled		(21,585	)		61.11
Nonvested awards outstanding at December 31, 2021		495,942		$	61.28

Restricted Stock Activity

The following table summarizes the restricted stock activity for the Plan:

	Awards			Weighted Average Grant Date Fair Value per Share
Unvested balance at December 31, 2020		201,985		$	58.07
Granted		102,309			66.20
Vested		(51,497	)		60.40
Canceled		(56,664	)		60.98
Unvested balance at December 31, 2021		196,133		$	60.87

Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2021

Earnings per Share [Abstract]

Computation of Basic and Diluted Earnings Per Share

	Year Ended December 31,
(in millions, except per share data)	2021		2020		2019
Net income attributable to MTI	$	164.4	$	112.4	$	132.7


Weighted average shares outstanding		33.6		34.2		35.0
Dilutive effect of stock options and stock units		0.2		—		0.1
Weighted average shares outstanding, adjusted		33.8		34.2		35.1

Basic earnings per share attributable to MTI	$	4.89	$	3.29	$	3.79

Diluted earnings per share attributable to MTI	$	4.86	$	3.29	$	3.78

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Taxes [Abstract]

Income from Operations Before Provision for Taxes by Domestic and Foreign Source

Income from operations before provision for taxes by domestic and foreign source is as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Income from operations before income taxes and income from affiliates and joint ventures:
Domestic	$	66.0	$	21.4	$	46.9
Foreign		136.3		116.6		110.4
	$	202.3	$	138.0	$	157.3

Provision (Benefit) for Taxes on Income

The provision (benefit) for taxes on income consists of the following:

	Year Ended December 31,
(millions of dollars)	2021			2020			2019
Domestic
Taxes currently payable
Federal	$	(5.3	)	$	(7.1	)	$	(3.3	)
State and local		0.4			0.2			0.8
Deferred income taxes		7.8			2.2			(6.6	)
Domestic tax provision (benefit)		2.9			(4.7	)		(9.1	)

Foreign
Taxes currently payable		33.4			34.0			26.7
Deferred income taxes		0.3			(4.9	)		5.2
Foreign tax provision		33.7			29.1			31.9
Total tax provision (benefit)	$	36.6		$	24.4		$	22.8

Reconciliation of Statutory to Effective Federal Tax Rate

The major elements contributing to the difference between the U.S. federal statutory tax rate and the consolidated effective tax rate are as follows:

	Year Ended December 31,
	2021			2020			2019
U.S. statutory rate		21.0	%		21.0	%		21.0	%

Depletion		(5.4	)%		(6.2	)%		(5.0	)%
Difference between tax provided on foreign earnings and the U.S. statutory rate		2.6	%		3.3	%		3.8	%
Global Intangible Low-Tax Income (GILTI)		0.7	%		0.4	%		—
Foreign Derived Intangible Income		(1.4	)%		(1.0	)%		(0.8	)%
State and local taxes, net of federal tax benefit		0.7	%		—			0.2	%
Tax credits and foreign dividends		(0.4	)%		(0.6	)%		(0.7	)%
Change in valuation allowance		—			—			1.0	%
Impact of uncertain tax positions		(1.1	)%		(0.2	)%		(5.0	)%
Impact of officer's non-deductible compensation		0.8	%		1.0	%		0.8	%
Impact of U.S. Tax Reform		—			—			(1.1	)%
Other		0.6	%		—			0.3	%
Consolidated effective tax rate		18.1	%		17.7	%		14.5	%

Deferred Tax Assets and Liabilities

	December 31,
(millions of dollars)	2021			2020
Deferred tax assets attributable to:
Accrued liabilities	$	29.7		$	29.8
Net operating loss carry forwards		31.8			31.1
Pension and post-retirement benefits costs		31.4			46.3
Other		22.4			28.2
Valuation allowance		(22.3	)		(20.9	)
Total deferred tax assets		93.0			114.5
Deferred tax liabilities attributable to:
Plant and equipment, principally due to differences in depreciation		178.8			169.5
Intangible assets		69.3			69.5
Other		10.0			13.9
Total deferred tax liabilities		258.1			252.9
Net deferred tax asset (liability)	$	(165.1	)	$	(138.4	)

Net deferred tax assets and net deferred tax liabilities are as follows:

	December 31,
(millions of dollars)	2021				2020
Net deferred tax asset, long-term		$	23.0			$	25.3
Net deferred tax liability, long-term			188.1				163.7
Net deferred tax asset (liability), long-term		$	(165.1	)		$	(138.4	)

Unrecognized Tax Benefits

The following table summarizes the activity related to our unrecognized tax benefits:

(millions of dollars)	2021			2020
Balance at beginning of the year	$	7.6		$	7.9
Increases related to current year tax positions		0.6			0.7
Increases related to new judgements		0.2			—
Decreases related to audit settlements and statue expirations		(3.3	)		(1.0	)

Balance at the end of the year	$	5.1		$	7.6

Inventories (Tables)

12 Months Ended

Dec. 31, 2021

Inventories [Abstract]

Inventories by Major Category

The following is a summary of inventories by major category:

	December 31,
(millions of dollars)	2021		2020
Raw materials	$	136.6	$	107.1
Work-in-process		10.7		9.0
Finished goods		99.4		85.6
Packaging and supplies		51.0		46.5
Total inventories	$	297.7	$	248.2

Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2021

Property, Plant and Equipment [Abstract]

Major Categories of Property, Plant and Equipment and Accumulated Depreciation and Depletion

The major categories of property, plant and equipment and accumulated depreciation and depletion are presented below:

	December 31,
(millions of dollars)	2021			2020
Mineral rights and reserves	$	554.7		$	565.8
Land		50.6			50.9
Buildings		229.2			225.6
Machinery and equipment		1,262.8			1,254.3
Furniture and fixtures and other		139.9			138.9
Construction in progress		59.2			41.4
		2,296.4			2,276.9
Less: accumulated depreciation and depletion		(1,247.3	)		(1,237.3	)
Property, plant and equipment, net	$	1,049.1		$	1,039.6

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2021

Goodwill and Other Intangible Assets [Abstract]

Goodwill

The balance of goodwill by segment and the activity occurring in the past two fiscal years is as follows:

(millions of dollars)	Performance Materials			Specialty Minerals			Refractories			Consolidated
Balance at December 31, 2019	$	751.2		$	12.5		$	43.7		$	807.4

Change in goodwill relating to:
Foreign exchange translation		1.2			0.2			(0.3	)		1.1
Total Changes	$	1.2		$	0.2		$	(0.3	)	$	1.1

Balance at December 31, 2020	$	752.4		$	12.7		$	43.4		$	808.5

Change in goodwill relating to:
Normerica acquisition		104.5			—			—			104.5
Foreign exchange translation		(3.9	)		(0.1	)		(1.5	)		(5.5	)
Total Changes	$	100.6		$	(0.1	)	$	(1.5	)	$	99.0

Balance at December 31, 2021	$	853.0		$	12.6		$	41.9		$	907.5

Other Intangible Assets

Acquired intangible assets subject to amortization as of December 31, 2021 and December 31, 2020 were as follows:

			December 31, 2021				December 31, 2020
	Weighted Average Useful Life (Years)		Gross Carrying Amount		Accumulated Amortization		Gross Carrying Amount		Accumulated Amortization
Tradenames		34	$	221.6	$	44.9	$	203.9	$	38.6
Technology		13		18.8		11.2		18.8		9.6
Patents and trademarks		19		6.4		6.4		6.4		6.1
Customer relationships		21		75.2		7.9		26.9		5.9
		29	$	322.0	$	70.4	$	256.0	$	60.2

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2021

Fair Value of Financial Instruments [Abstract]

Fair Value of Financial Assets and Liabilities on a Recurring Basis

(millions of dollars)				Fair Value Measurements Using
	Asset / (Liability) Balance at			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs			Significant Unobservable Inputs
Description	December 31, 2021			(Level 1)		(Level 2)			(Level 3)
Deferred compensation plan assets	$	14.6		$	—	$	14.6		$	—

Supplementary pension plan assets		16.8			—		16.8			—

Cross currency rate swap		8.2			—		8.2			—

Interest rate swaps		(4.0	)		—		(4.0	)		—

				Fair Value Measurements Using
	Asset / (Liability) Balance at			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs			Significant Unobservable Inputs
Description	December 31, 2020			(Level 1)		(Level 2)			(Level 3)
Deferred compensation plan assets	$	14.2		$	—	$	14.2		$	—

Supplementary pension plan assets		15.0			—		15.0			—

Cross currency rate swap		0.4			—		0.4			—

Interest rate swaps		(7.6	)		—		(7.6	)		—

Long-Term Debt and Commitments (Tables)

12 Months Ended

Dec. 31, 2021

Long-Term Debt and Commitments [Abstract]

Long Term Debt

The following is a summary of long-term debt:

	December 31,
(millions of dollars)	2021		2020
Term Loan Facility- Variable Tranche due February 14, 2024, net of unamortized discount and deferred financing costs of $8.8 million and $12.4 million	$	539.2	$	535.6
Senior Notes due 2028, net of unamortized deferred financing costs of $5.4 million		394.6		393.9
Netherlands Term Loan due 2022		0.2		0.6
Japan Loan Facilities		3.0		4.1
Total	$	937.0	$	934.2
Less: Current maturities		0.8		1.0
Long-term debt	$	936.2	$	933.2

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21506-112644

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495743-112612

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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+ Details

Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2021

Benefit Plans [Abstract]

Pension Obligation and Funded Status

The following table set forth Company's pension obligation and funded status at December 31:

	Pension Benefits						Post-Retirement Benefits
(millions of dollars)	2021			2020			2021			2020
Change in benefit obligations:
Beginning projected benefit obligation	$	534.3		$	484.4		$	4.6		$	5.9
Service cost		7.7			7.7			0.1			0.2
Interest cost		7.9			10.5			0.1			0.2
Actuarial (gain)/loss		(23.8	)		56.5			(0.3	)		(1.3	)
Benefits paid		(12.4	)		(12.3	)		(0.5	)		(0.4	)
Settlements		(16.3	)		(18.4	)		(1.6	)		—
Foreign exchange impact		(2.7	)		5.5			(0.1	)		—
Other		0.3			0.4			—			—
Ending projected benefit obligation		495.0			534.3			2.3			4.6

Change in plan assets:
Beginning fair value		358.2			340.0			—			—
Actual return on plan assets		44.0			31.1			—			—
Employer contributions		10.7			11.8			0.5			0.4
Plan participants' contributions		0.3			0.3			—			—
Benefits paid		(12.4	)		(12.2	)		(0.5	)		(0.4	)
Settlements		(17.1	)		(16.9	)		—			—
Foreign exchange impact		(2.3	)		4.1			—			—
Ending fair value		381.4			358.2			—			—

Funded status	$	(113.6	)	$	(176.1	)	$	(2.3	)	$	(4.6	)

Amounts Recognized in Consolidated Balance Sheet

Amounts recognized in the consolidated balance sheet consist of:

	Pension Benefits								Post-Retirement Benefits
(millions of dollars)	2021				2020				2021				2020
Current liability		$	(1.4	)		$	(1.4	)		$	(0.2	)		$	(0.3	)
Non-current liability			(112.2	)			(174.7	)			(2.1	)			(4.3	)
Recognized liability		$	(113.6	)		$	(176.1	)		$	(2.3	)		$	(4.6	)

Amounts Recognized in Accumulated Other Comprehensive Income

Amounts recognized in accumulated other comprehensive income, net of related tax effects, consist of:

	Pension Benefits						Post-Retirement Benefits
(millions of dollars)	2021			2020			2021				2020
Net actuarial (gain) loss		$	73.2		$	119.0		$	(3.7	)		$	(4.2	)
Prior service cost			0.1			0.1			—				—
Amount recognized end of year		$	73.3		$	119.1		$	(3.7	)		$	(4.2	)

Change in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income

Changes in the Plan assets and benefit obligations recognized in other comprehensive income:

	Pension Benefits					Post-Retirement Benefits
(millions of dollars)	2021		2020			2021			2020
Current year actuarial gain (loss)	$	36.7	$	(29.6	)	$	0.1		$	0.9
Amortization of actuarial (gain) loss		9.0		10.5			(0.6	)		(0.5	)
Amortization of prior service credit (gain) loss		—		—			—			—
Total recognized in other comprehensive income	$	45.7	$	(19.1	)	$	(0.5	)	$	0.4

Net Periodic Benefit Cost

The components of net periodic benefit costs are as follows:

	Pension Benefits									Post-Retirement Benefits
(millions of dollars)	2021			2020			2019			2021			2020			2019
Service cost	$	7.7		$	7.7		$	6.8		$	0.1		$	0.2		$	0.2
Interest cost		7.9			10.5			14.0			0.1			0.2			0.2
Expected return on plan assets		(22.0	)		(20.1	)		(18.2	)		—			—			—
Amortization of prior service cost		—			—			—			—			—			—
Recognized net actuarial (gain) loss		12.1			13.9			10.1			(0.8	)		(0.9	)		(0.9	)
Settlement/curtailment (gain) loss		3.4			6.4			(0.1	)		(1.6	)		—			—
Net periodic benefit cost	$	9.1		$	18.4		$	12.6		$	(2.2	)	$	(0.5	)	$	(0.5	)

Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost and Benefit Obligation

	Year Ended December 31,
	2021			2020			2019
Discount rate		2.01	%		2.74	%		3.75	%
Expected return on plan assets		6.28	%		6.32	%		6.43	%
Rate of compensation increase		2.72	%		2.72	%		3.01	%
Interest crediting rate		2.25	%		3.75	%		2.57	%

The weighted average assumptions used to determine benefit obligations for the pension benefit plans and other benefit plans at December 31, 2021, 2020 and 2019 are as follows:

	Year Ended December 31,
	2021			2020			2019
Discount rate		2.42	%		2.01	%		2.75	%
Rate of compensation increase		2.74	%		2.98	%		2.99	%

Weighted Average Asset Allocation Percentages

The Company's pension plan weighted average asset allocation percentages at December 31, 2021 and 2020 by asset category are as follows:

	December 31,
	2021			2020
Asset Category
Equity securities		54.2	%		55.8	%
Fixed income securities		30.6	%		27.8	%
Real estate		0.3	%		0.3	%
Other		14.9	%		16.1	%
Total		100.0	%		100.0	%

Fair Value of Plan Assets

The Company's pension plan fair values at December 31, 2021 and 2020 by asset category are as follows:

	December 31,
(millions of dollars)	2021		2020
Asset Category
Equity securities	$	206.7	$	200.0
Fixed income securities		116.5		99.7
Real estate		1.0		1.0
Other		57.1		57.5
Total	$	381.3	$	358.2

The following table presents domestic and foreign pension plan assets information at December 31, 2021, 2020 and 2019 (the measurement date of pension plan assets):

	U.S. Plans									International Plans
(millions of dollars)	2021			2020			2019			2021			2020			2019
Fair value of plan assets		$	293.7		$	271.6		$	261.5		$	87.6		$	86.6		$	78.5

Defined Benefit Pension Plan Assets Measured at Fair Value

The following table summarizes our defined benefit pension plan assets measured at fair value as of December 31, 2021:

	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(millions of dollars)	(Level 1)		(Level 2)		(Level 3)		Total
Pension Assets Fair Value as of December 31, 2021
Equity securities
US equities	$	182.7	$	—	$	—	$	182.7
Non-US equities		24.0		—		—		24.0

Fixed income securities
Corporate debt instruments		96.4		20.1		—		116.5

Real estate and other
Real estate		—		—		1.0		1.0
Other		0.4		51.7		5.0		57.1

Total assets	$	303.5	$	71.8	$	6.0	$	381.3

The following table summarizes our defined benefit pension plan assets measured at fair value as of December 31, 2020:

	Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
(millions of dollars)	(Level 1)		(Level 2)		(Level 3)		Total
Pension Assets Fair Value as of December 31, 2020
Equity securities
US equities	$	182.0	$	—	$	—	$	182.0
Non-US equities		18.0		—		—		18.0

Fixed income securities
Corporate debt instruments		80.4		19.3		—		99.7

Real estate and other
Real estate		—		—		1.0		1.0
Other		0.3		49.9		7.3		57.5

Total assets	$	280.7	$	69.2	$	8.3	$	358.2

Reconciliation of Changes in Fair Value Measurement of Plan Assets Using Significant Unobservable Inputs

The following is a reconciliation of changes in fair value measurement of plan assets using significant unobservable inputs (Level 3):

(millions of dollars)
Beginning balance at December 31, 2019	$	21.0
Purchases, sales, settlements		—
Actual return on plan assets still held at reporting date		(12.8	)
Foreign exchange impact		0.1
Ending balance at December 31, 2020	$	8.3
Purchases, sales, settlements		—
Actual return on plan assets still held at reporting date		(2.3	)
Foreign exchange impact		-
Ending balance at December 31, 2021	$	6.0

Estimated Future Benefit Payments

The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid:

(millions of dollars)	Pension Benefits		Other Benefits
2022	$	24.1	$	0.2
2023	$	25.9	$	0.2
2024	$	26.3	$	0.2
2025	$	26.1	$	0.2
2026	$	26.6	$	0.2
2027-2031	$	130.0	$	0.8

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2021

Stockholders' Equity [Abstract]

Stock Option and Restricted Stock Activity

The following table summarizes stock option and restricted stock activity for the Plans:

				Stock Options					Restricted Shares
	Shares Available for Grant			Shares			Weighted Average Exercise Price per Share ($)		Shares			Weighted Average Exercise Price per Share ($)
Balance January 1, 2019		866,023			1,054,259		$	54.04		134,578		$	68.64
Granted		(388,162	)		271,261			54.44		116,901			54.51
Exercised/vested		—			(79,686	)		27.26		(40,776	)		60.79
Canceled		51,181			(18,214	)		66.93		(32,967	)		61.87
Balance December 31, 2019		529,042			1,227,620			55.83		177,736			62.40
Authorized		1,300,000			—			—		—			—
Granted		(394,290	)		286,078			57.67		108,212			56.93
Exercised/vested		—			(93,099	)		35.11		(43,702	)		66.07
Canceled		97,494			(57,233	)		63.92		(40,261	)		65.42
Balance December 31, 2020		1,532,246			1,363,366			57.29		201,985			58.07
Granted		(358,078	)		255,769			66.00		102,309			66.20
Exercised/vested		—			(251,195	)		51.12		(51,497	)		60.40
Canceled		94,602			(37,938	)		64.92		(56,664	)		60.98
Balance December 31, 2021		1,268,770			1,330,002		$	59.91		196,133		$	60.87

Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2021

Accumulated Other Comprehensive Income (Loss) [Abstract]

Accumulated Other Comprehensive Loss, Net of Related Tax

Accumulated other comprehensive income (loss) at December 31 comprised of the following components:

	December 31,
(millions of dollars)	2021			2020
Cumulative foreign currency translation	$	(269.8	)	$	(190.8	)
Unrecognized pension costs (net of tax benefit of $21.4 in 2021 and $64.6 in 2020)		(69.6	)		(114.9	)
Unrealized gain (loss) on cash flow hedges (net of tax expense (benefit) of $3.0 in 2021 and $(3.1) in 2020)		5.8			(2.6	)
	$	(333.6	)	$	(308.3	)

Changes in Other Comprehensive Income (Loss) by Component

The following table summarizes the changes in other comprehensive income (loss) by component:

	Year Ended December 31,
	2021									2020									2019
(millions of dollars)	Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount			Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount			Pre-Tax Amount			Tax (Expense) Benefit			Net-of- Tax Amount
Foreign currency translation adjustment	$	(78.9	)	$	—		$	(78.9	)	$	10.9		$	—		$	10.9		$	(29.9	)	$	—		$	(29.9	)

Pension plans:
Net actuarial gains (losses) and prior service costs arising during the period		49.3			(12.5	)		36.8			(37.9	)		9.2			(28.7	)		(30.6	)		7.4			(23.2	)
Amortization of net actuarial (gains) losses and prior service costs		11.3			(2.9	)		8.4			13.4			(3.4	)		10.0			9.4			(2.3	)		7.1

Unrealized gains (losses) on cash flow hedges		11.4			(3.0	)		8.4			(11.6	)		3.1			(8.5	)		0.3			(0.1	)		0.2

Total other comprehensive income (loss)	$	(6.9	)	$	(18.4	)	$	(25.3	)	$	(25.2	)	$	8.9		$	(16.3	)	$	(50.8	)	$	5.0		$	(45.8	)

Accounting for Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2021

Accounting for Asset Retirement Obligations [Abstract]

Reconciliation of Asset Retirement Obligations

The following is a reconciliation of asset retirement obligations as of December 31, 2021 and 2020:

	December 31,
(millions of dollars)	2021			2020
Asset retirement obligation, beginning of period	$	24.1		$	23.9
Accretion expense		1.9			2.3
Other		1.2			1.1
Payments		(2.3	)		(3.4	)
Foreign currency translation		(0.5	)		0.2
Asset retirement obligation, end of period	$	24.4		$	24.1

Segment and Related Information (Tables)

12 Months Ended

Dec. 31, 2021

Segment Information

Segment information for the years ended December 31, 2021, 2020 and 2019 was as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
Performance Materials	$	976.0	$	825.8	$	918.5
Specialty Minerals		578.9		510.9		574.4
Refractories		303.4		258.1		298.1
Total		1,858.3		1,594.8		1,791.0

Income from Operations
Performance Materials		125.0		108.8		104.9
Specialty Minerals		72.9		67.8		83.1
Refractories		49.3		35.5		39.8
Total		247.2		212.1		227.8

Depreciation, Depletion and Amortization
Performance Materials		49.2		47.4		51.0
Specialty Minerals		38.4		39.6		40.4
Refractories		7.0		6.9		7.0
Total		94.6		93.9		98.4

Segment Assets
Performance Materials		2,393.2		2,219.1		2,212.7
Specialty Minerals		605.9		559.6		525.1
Refractories		293.1		290.8		293.2
Total		3,292.2		3,069.5		3,031.0

Capital Expenditures
Performance Materials		22.0		14.6		21.5
Specialty Minerals		51.7		46.5		37.7
Refractories		9.7		5.5		5.7
Total		83.4		66.6		64.9

Reconciliation of Significant Items from Segments to Consolidated Totals

A reconciliation of the totals reported for the operating segments to the applicable line items in the consolidated financial statements is as follows:

	Year Ended December 31,
(millions of dollars)	2021			2020			2019
Income from Operations before Provision for Taxes on Income
Income from operations for reportable segments	$	247.2		$	212.1		$	227.8
Litigation expenses		—			(10.4	)		(10.9	)
Acquisition-related expenses		(4.0	)		(3.1	)		—
Unallocated corporate expenses		(7.5	)		(10.7	)		(8.2	)
Consolidated income from operations		235.7			187.9			208.7
Non-operating deductions, net		(33.4	)		(49.9	)		(51.4	)
Income from operations before provision for taxes and equity in earnings		202.3			138.0			157.3

Total Assets
Total segment assets		3,292.2			3,069.5			3,031.0
Corporate assets		82.0			139.9			81.6
Consolidated total assets		3,374.2			3,209.4			3,112.6

Capital Expenditures
Total segment capital expenditures		83.4			66.6			64.9
Corporate capital expenditures		2.6			0.2			0.1
Consolidated capital expenditures		86.0			66.8			65.0

Financial Information Related to Operations by Geographic Area

Financial information relating to the Company's operations by geographic area was as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Net Sales
United States	$	959.6	$	822.5	$	962.4

Canada/Latin America		99.8		70.5		80.2
Europe/Africa		441.9		410.0		435.3
Asia		357.0		291.8		313.1
Total International		898.7		772.3		828.6
Consolidated net sales		1,858.3		1,594.8		1,791.0

Long-Lived Assets
United States	$	1,925.3	$	1,723.2	$	1,742.3

Canada/Latin America		10.6		11.3		13.0
Europe/Africa		151.1		182.9		190.7
Asia		120.6		126.5		117.2
Total International		282.3		320.7		320.9
Consolidated long-lived assets		2,207.6		2,043.9		2,063.2

Sales by Product Category

The Company's sales by product category are as follows:

	Year Ended December 31,
(millions of dollars)	2021		2020		2019
Household, Personal Care & Specialty Products	$	460.5	$	380.2	$	376.6
Metalcasting		319.2		258.1		291.2
Environmental Products		136.3		131.6		181.8
Building Materials		60.0		55.9		68.9
Paper PCC		349.7		308.4		364.9
Specialty PCC		77.1		69.3		69.1
Ground Calcium Carbonate		98.1		89.3		91.3
Talc		54.0		43.9		49.1
Refractory Products		237.1		212.3		244.8
Metallurgical Products		66.3		45.8		53.3
Total	$	1,858.3	$	1,594.8	$	1,791.0

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021
Cash Equivalents and Short-term Investments [Abstract]
Short-term investments	$ 4.9	$ 4.1	$ 4.9
Unrealized holding gains and losses on short-term bank investments			$ 0.0
Trade Accounts Receivable [Abstract]
Past due threshold for individual collectability review			90 days
Allowance for doubtful accounts	15.0	15.0	$ 15.0
Property, Plant and Equipment [Abstract]
Initial term of long term evergreen contracts			10 years
Investment in Joint Ventures [Abstract]
Equity method investment	17.5	17.0	$ 17.5
Revenue Recognition [Abstract]
Revenue adjustments	$ 0.0	$ 0.0
Buildings [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			3.00%
Buildings [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			6.67%
Machinery and Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			6.67%
Machinery and Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			12.50%
Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			8.00%
Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			12.50%
Computer Equipment and Software-related Assets [Member] \| Minimum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			12.50%
Computer Equipment and Software-related Assets [Member] \| Maximum [Member]
Property, Plant and Equipment [Abstract]
Annual rates of depreciation			25.00%
PCC Production Facilities [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life			15 years
Machinery and Equipment for Natural Stone Mining and Processing Plants and Chemical Plants [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life			15 years

Leases (Details) - USD ($) $ in Millions	12 Months Ended
Leases (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Lease Cost [Abstract]
Operating lease cost	$ 15.2	$ 15.2	$ 15.5
Short-term lease cost	0.1	0.1	1.1
Total	15.3	15.3	$ 16.6
Operating cash flows information [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	16.0
Non-cash activity [Abstract]
Right-of-use assets obtained in the exchange for operating lease liabilities	$ 11.5
Weighted Average Remaining Lease Term and Discount Rates [Abstract]
Weighted-average remaining operating lease term	7 years 2 months 19 days
Weighted-average operating leases discount rate	5.00%
Outstanding Lease Assets and Liabilities [Abstract]
Right-of-use asset	$ 49.6	$ 50.9
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Lease liability - current	$ 11.7	$ 11.7
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current	Other Liabilities, Current
Lease liability - non-current	$ 47.2	$ 49.2
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Future Minimum Lease Payments [Abstract]
2022	$ 14.3
2023	12.1
2024	9.5
2025	8.0
2026	7.4
Thereafter	19.3
Total future minimum lease payments	70.6
Less imputed interest	(11.7)
Total	$ 58.9
Minimum [Member]
Leases [Abstract]
Remaining lease term	1 year
Maximum [Member]
Leases [Abstract]
Remaining lease term	50 years

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Abstract]
Net sales	$ 1,858.3	$ 1,594.8	$ 1,791.0
Household, Personal Care and Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	460.5	380.2	376.6
Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net sales	319.2	258.1	291.2
Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	136.3	131.6	181.8
Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net sales	60.0	55.9	68.9
Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net sales	349.7	308.4	364.9
Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net sales	77.1	69.3	69.1
Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net sales	98.1	89.3	91.3
Talc [Member]
Disaggregation of Revenue [Abstract]
Net sales	54.0	43.9	49.1
Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	237.1	212.3	244.8
Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	66.3	45.8	53.3
Performance Materials [Member]
Disaggregation of Revenue [Abstract]
Net sales	976.0	825.8	918.5
Performance Materials [Member] \| Household, Personal Care and Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	460.5	380.2	376.6
Performance Materials [Member] \| Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net sales	319.2	258.1	291.2
Performance Materials [Member] \| Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	136.3	131.6	181.8
Performance Materials [Member] \| Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net sales	60.0	55.9	68.9
Specialty Minerals [Member]
Disaggregation of Revenue [Abstract]
Net sales	578.9	510.9	574.4
Specialty Minerals [Member] \| Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net sales	349.7	308.4	364.9
Specialty Minerals [Member] \| Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net sales	77.1	69.3	69.1
Specialty Minerals [Member] \| Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net sales	98.1	89.3	91.3
Specialty Minerals [Member] \| Talc [Member]
Disaggregation of Revenue [Abstract]
Net sales	54.0	43.9	49.1
Refractories [Member]
Disaggregation of Revenue [Abstract]
Net sales	303.4	258.1	298.1
Refractories [Member] \| Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	237.1	212.3	244.8
Refractories [Member] \| Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net sales	$ 66.3	$ 45.8	$ 53.3

Acquisitions (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		5 Months Ended	12 Months Ended
Acquisitions (Details) - USD ($) $ in Millions	Jul. 26, 2021	Nov. 30, 2021	Dec. 31, 2021	Sep. 27, 2020	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Oct. 03, 2021
Acquisitions [Abstract]
Acquisition of business						$ 194.4	$ 9.2	$ 0.0
Preliminary Purchase Price Allocation [Abstract]
Goodwill			$ 907.5		$ 907.5	$ 907.5	808.5	807.4
Increase/(Decrease) [Abstract]
Estimated useful life of intangible assets acquired						29 years
Acquisition-related expenses						$ 4.0	3.1	$ 0.0
Normerica [Member]
Acquisitions [Abstract]
Acquisition of business	$ 189.0
Sales						48.6
Total consideration transferred, net of cash acquired					187.5
Preliminary Purchase Price Allocation [Abstract]
Accounts receivable			8.4		8.4	8.4			$ 8.4
Inventories			5.1		5.1	5.1			5.1
Other current assets			1.4		1.4	1.4			1.4
Property, plant and equipment			21.2		21.2	21.2			21.2
Goodwill			104.5		104.5	104.5			106.0
Intangible assets			68.1		68.1	68.1			67.0
Total assets acquired			208.7		208.7	208.7			209.1
Accounts payable			12.8		12.8	12.8			12.8
Accrued expenses			8.4		8.4	8.4			9.4
Total liabilities assumed			21.2		21.2	21.2			22.2
Net assets acquired			187.5		187.5	187.5			$ 186.9
Increase/(Decrease) [Abstract]
Accounts receivable			0.0
Inventories			0.0
Other current assets			0.0
Property, plant and equipment			0.0
Goodwill			(1.5)
Intangible assets			1.1
Assets			(0.4)
Accounts payable			0.0
Accrued expenses			(1.0)
Total liabilities assumed			(1.0)
Net assets acquired			0.6
Acquisition-related expenses						4.0	$ 3.1
Normerica [Member] \| Trade Names [Member]
Preliminary Purchase Price Allocation [Abstract]
Intangible assets			18.1		18.1	$ 18.1
Increase/(Decrease) [Abstract]
Estimated useful life of intangible assets acquired						15 years
Normerica [Member] \| Customer Relationships [Member]
Preliminary Purchase Price Allocation [Abstract]
Intangible assets			$ 50.0		$ 50.0	$ 50.0
Increase/(Decrease) [Abstract]
Estimated useful life of intangible assets acquired						20 years
Specialty PCC Assets from Company in Midwest United States [Member]
Acquisitions [Abstract]
Acquisition of assets		$ 6.9
Assets of Mining and Hauling Company in Western United States [Member]
Acquisitions [Abstract]
Acquisition of assets				$ 9.2

Restructuring and Other Items, net (Details) $ in Millions	3 Months Ended			12 Months Ended
Restructuring and Other Items, net (Details) $ in Millions	Oct. 03, 2021 USD ($)	Sep. 27, 2020 USD ($)	Jun. 28, 2020 USD ($) Mill	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Restructuring and Other Items, Net [Abstract]
Number of paper mills being idled indefinitely \| Mill			2
Restructuring Charges [Abstract]
Asset write-down charges				$ 0.7	$ 7.1	$ 7.5
Severance and other related costs				0.4	0.5	5.7
Total restructuring and other items, net				1.1	7.6	13.2
Restructuring Liability [Roll Forward]
Restructuring liability, beginning of period				3.6	5.0
Additional provisions				0.1	0.3
Cash payments				(1.5)	(1.6)
Other				0.0	(0.1)
Restructuring liability, end of period				2.2	3.6	5.0
Performance Materials [Member]
Restructuring Charges [Abstract]
Asset write-down charges				0.0	0.0	5.9
Severance and other related costs				0.0	0.0	2.9
Specialty Minerals [Member]
Restructuring Charges [Abstract]
Asset write-down charges				0.7	7.1	1.6
Severance and other related costs				0.4	0.5	0.9
Specialty Minerals [Member] \| Paper PCC [Member]
Restructuring and Other Items, Net [Abstract]
Number of mills with lease terminations \| Mill			1
Restructuring Charges [Abstract]
Asset write-down charges	$ 0.7	$ 1.1	$ 6.0
Severance and other related costs	$ 0.4		$ 0.3
Refractories [Member]
Restructuring Charges [Abstract]
Severance and other related costs				0.0	0.0	0.8
Corporate [Member]
Restructuring Charges [Abstract]
Severance and other related costs				$ 0.0	$ 0.0	$ 1.1

Stock-Based Compensation, Stock Award and Incentive Plan and Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee service share-based compensation, aggregate disclosures [Abstract]
Share based compensation costs	$ 10.7	$ 10.2	$ 8.1
Stock Options [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Term of stock options granted under Plan	10 years
Vesting period	3 years
Share based compensation costs	$ 4.9	4.6	4.8
Tax benefit of share-based compensation	$ 1.3	$ 1.2	$ 1.3
Forfeiture rate assumed	8.38%	8.45%	8.85%
Weighted average grant date fair value for stock options granted (in dollars per share)	$ 21.62	$ 18.99	$ 18.86
Weighted average grant date fair value for stock options vested (in dollars per share)	$ 20.56	$ 23.85	$ 22.46
Total intrinsic value of stock options exercised	$ 6.1	$ 2.3	$ 2.2
Weighted Average Assumptions [Abstract]
Expected life	6 years 10 months 24 days	6 years 8 months 12 days	6 years 7 months 6 days
Interest rate	0.71%	1.67%	2.62%
Volatility	32.04%	30.34%	30.26%
Expected dividend yield	0.31%	0.35%	0.37%
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	1,363,366
Granted (in shares)	255,769
Exercised (in shares)	(251,195)
Canceled (in shares)	(37,938)
Balance, end of year (in shares)	1,330,002	1,363,366
Exercisable, end of year (in shares)	834,060
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 57.29
Granted (in dollars per share)	66.00
Exercised (in dollars per share)	51.12
Canceled (in dollars per share)	64.92
Balance, end of year (in dollars per share)	59.91	$ 57.29
Exercisable, end of year (in dollars per share)	$ 59.09
Weighted Average Remaining Contractual Life [Abstract]
Outstanding options, end of year	6 years 1 month 20 days
Exercisable options, end of year	4 years 9 months 18 days
Aggregate Intrinsic Value [Abstract]
Outstanding options, end of year	$ 18.7
Exercisable options, end of year	$ 12.8
Additional Information [Abstract]
Closing stock price on last business day of the period (in dollars per share)	$ 73.15
Weighted average intrinsic value of options exercised (in dollars per share)	$ 24.43	$ 24.41	$ 27.21
Unrecognized stock-based compensation expense	$ 4.9
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Nonvested Stock Options [Member]
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	487,160
Granted (in shares)	255,769
Vested (in shares)	(225,402)
Canceled (in shares)	(21,585)
Balance, end of year (in shares)	495,942	487,160
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 58.61
Granted (in dollars per share)	66.00
Vested (in dollars per share)	60.88
Canceled (in dollars per share)	61.11
Balance, end of year (in dollars per share)	$ 61.28	$ 58.61

Stock-Based Compensation, Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee service share-based compensation, aggregate disclosures [Abstract]
Share based compensation costs	$ 10.7	$ 10.2	$ 8.1
Restricted Stock [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Unrecognized stock-based compensation expense	$ 6.4
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Share based compensation costs	$ 5.9	5.6	5.2
Reversals of compensation expense related to restricted stock forfeitures	$ 2.6	$ 2.3	$ 1.9
Restricted Stock [Roll Forward]
Balance, beginning of year (in shares)	201,985	177,736	134,578
Granted (in shares)	102,309	108,212	116,901
Vested (in shares)	(51,497)	(43,702)	(40,776)
Canceled (in shares)	(56,664)	(40,261)	(32,967)
Balance, end of year (in shares)	196,133	201,985	177,736
Weighted Average Grant Date Fair Value [Abstract]
Balance, beginning of year (in dollars per share)	$ 58.07	$ 62.40	$ 68.64
Granted (in dollars per share)	66.20	56.93	54.51
Vested (in dollars per share)	60.40	66.07	60.79
Canceled (in dollars per share)	60.98	65.42	61.87
Balance, end of year (in dollars per share)	$ 60.87	$ 58.07	$ 62.40

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Earnings per Share [Abstract]
Net income attributable to MTI	$ 164.4	$ 112.4	$ 132.7
Weighted average shares outstanding (in shares)	33,600,000	34,200,000	35,000,000.0
Dilutive effect of stock options and stock units (in shares)	200,000	0	100,000
Weighted average shares outstanding, adjusted (in shares)	33,800,000	34,200,000	35,100,000
Basic earnings per share attributable to MTI (in dollars per share)	$ 4.89	$ 3.29	$ 3.79
Diluted earnings per share attributable to MTI (in dollars per share)	$ 4.86	$ 3.29	$ 3.78
Stock Options [Member]
Earnings per Share [Abstract]
Options outstanding (in shares)	1,330,002	1,363,366	1,227,620
Anti-dilutive securities not included in computation of diluted earnings per share (in shares)	510,683	591,322	825,331

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income from operations before income taxes and income from affiliates and joint ventures [Abstract]
Domestic	$ 66.0	$ 21.4	$ 46.9
Foreign	136.3	116.6	110.4
Income from operations before tax and equity in earnings	202.3	138.0	157.3
Domestic [Abstract]
Taxes currently payable, Federal	(5.3)	(7.1)	(3.3)
Taxes currently payable, State and local	0.4	0.2	0.8
Deferred income taxes	7.8	2.2	(6.6)
Domestic tax provision (benefit)	2.9	(4.7)	(9.1)
Foreign [Abstract]
Taxes currently payable	33.4	34.0	26.7
Deferred income taxes	0.3	(4.9)	5.2
Foreign tax provision	33.7	29.1	31.9
Total tax provision (benefit)	$ 36.6	$ 24.4	$ 22.8
Reconciliation of U.S. federal statutory tax rate to effective tax rate [Abstract]
U.S. statutory rate	21.00%	21.00%	21.00%
Depletion	(5.40%)	(6.20%)	(5.00%)
Difference between tax provided on foreign earnings and the U.S. statutory rate	2.60%	3.30%	3.80%
Global Intangible Low-Tax Income (GILTI)	0.70%	0.40%	0.00%
Foreign Derived Intangible Income	(1.40%)	(1.00%)	(0.80%)
State and local taxes, net of federal tax benefit	0.70%	0.00%	0.20%
Tax credits and foreign dividends	(0.40%)	(0.60%)	(0.70%)
Change in valuation allowance	0.00%	0.00%	1.00%
Impact of uncertain tax positions	(1.10%)	(0.20%)	(5.00%)
Impact of officer's non-deductible compensation	0.80%	1.00%	0.80%
Impact of U.S. Tax Reform	0.00%	0.00%	(1.10%)
Other	0.60%	0.00%	0.30%
Consolidated effective tax rate	18.10%	17.70%	14.50%
Deferred tax assets attributable to [Abstract]
Accrued liabilities	$ 29.7	$ 29.8
Net operating loss carry forwards	31.8	31.1
Pension and post-retirement benefits costs	31.4	46.3
Other	22.4	28.2
Valuation allowance	(22.3)	(20.9)
Total deferred tax assets	93.0	114.5
Deferred tax liabilities attributable to [Abstract]
Plant and equipment, principally due to differences in depreciation	178.8	169.5
Intangible assets	69.3	69.5
Other	10.0	13.9
Total deferred tax liabilities	258.1	252.9
Net deferred tax asset (liability), long-term	(165.1)	(138.4)
Current and long-term portion of net deferred tax assets [Abstract]
Net deferred tax asset, long-term	23.0	25.3
Net deferred tax liability, long-term	188.1	163.7
Net deferred tax asset (liability), long-term	(165.1)	(138.4)
Operating loss carryforwards [Abstract]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	31.8
Unrecognized tax benefits [Abstract]
Unrecognized tax benefits that would impact effective tax rate	3.6
Unrecognized tax benefits [Roll forward]
Balance at beginning of the year	7.6	7.9
Increases related to current year tax positions	0.6	0.7
Increases related to new judgments	0.2	0.0
Decreases related to audit settlements and statute expirations	(3.3)	(1.0)
Balance at the end of the year	5.1	7.6	$ 7.9
Income Tax Penalties and Interest Expense [Abstract]
Unrecognized tax benefits, interest and penalties	0.8
Unrecognized tax benefits, accrued interest and penalties	1.2
Cash paid for income taxes [Abstract]
Net cash Income taxes paid	42.5	$ 28.5	$ 29.5
Undistributed earnings of foreign subsidiaries [Abstract]
Foreign subsidiaries' undistributed earnings	481.4
Deferred tax liabilities with respect to foreign withholding taxes or state taxes have been recognized	0.0
Finite lived tax loss carry forwards [Member]
Operating loss carryforwards [Abstract]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	$ 17.8
Expiration period	20 years
Indefinite lived tax loss carry forwards [Member]
Operating loss carryforwards [Abstract]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	$ 14.0

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Inventories [Abstract]
Raw materials	$ 136.6	$ 107.1
Work-in-process	10.7	9.0
Finished goods	99.4	85.6
Packaging and supplies	51.0	46.5
Total inventories	$ 297.7	$ 248.2

Property, Plant and Equipment (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Nov. 30, 2021	Sep. 27, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			$ 2,296.4	$ 2,276.9
Less: accumulated depreciation and depletion			(1,247.3)	(1,237.3)
Property, plant and equipment, net			1,049.1	1,039.6
Property, Plant and Equipment [Abstract]
Depreciation and depletion expense			77.4	77.9	$ 82.1
Mineral Rights and Reserves [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			554.7	565.8
Land [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			50.6	50.9
Buildings [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			229.2	225.6
Machinery and Equipment [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			1,262.8	1,254.3
Furniture and Fixtures and Other [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			139.9	138.9
Construction in Progress [Member]
Property, plant and equipment, net [Abstract]
Property, plant and equipment, gross			$ 59.2	$ 41.4
Specialty PCC Assets from Company in Midwest United States [Member]
Property, Plant and Equipment [Abstract]
Acquisition of assets	$ 6.9
Assets of Mining and Hauling Company in Western United States [Member]
Property, Plant and Equipment [Abstract]
Acquisition of assets		$ 9.2

Goodwill and Other Intangible Assets, Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Balance Beginning	$ 808.5	$ 807.4
Change in goodwill relating to [Abstract]
Acquisition of Normerica	104.5
Foreign exchange translation	(5.5)	1.1
Total changes	99.0	1.1
Balance Ending	907.5	808.5
Performance Materials [Member]
Goodwill [Roll Forward]
Balance Beginning	752.4	751.2
Change in goodwill relating to [Abstract]
Acquisition of Normerica	104.5
Foreign exchange translation	(3.9)	1.2
Total changes	100.6	1.2
Balance Ending	853.0	752.4
Specialty Minerals [Member]
Goodwill [Roll Forward]
Balance Beginning	12.7	12.5
Change in goodwill relating to [Abstract]
Acquisition of Normerica	0.0
Foreign exchange translation	(0.1)	0.2
Total changes	(0.1)	0.2
Balance Ending	12.6	12.7
Refractories [Member]
Goodwill [Roll Forward]
Balance Beginning	43.4	43.7
Change in goodwill relating to [Abstract]
Acquisition of Normerica	0.0
Foreign exchange translation	(1.5)	(0.3)
Total changes	(1.5)	(0.3)
Balance Ending	$ 41.9	$ 43.4

Goodwill and Other Intangible Assets, Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Intangible Assets Subject to Amortization [Abstract]
Weighted average useful life	29 years
Gross carrying amount	$ 322.0	$ 256.0
Accumulated amortization	$ 70.4	60.2
Future Amortization Expense [Abstract]
Weighted average amortization period	29 years
Amortization expense	$ 10.6	9.3	$ 9.1
Estimated amortization expense, 2022	12.7
Estimated amortization expense, 2023	12.6
Estimated amortization expense, 2024	12.6
Estimated amortization expense, 2025	12.6
Estimated amortization expense, 2026	12.6
Estimated amortization expense, thereafter	$ 188.3
Trade Names [Member]
Intangible Assets Subject to Amortization [Abstract]
Weighted average useful life	34 years
Gross carrying amount	$ 221.6	203.9
Accumulated amortization	$ 44.9	38.6
Technology [Member]
Intangible Assets Subject to Amortization [Abstract]
Weighted average useful life	13 years
Gross carrying amount	$ 18.8	18.8
Accumulated amortization	$ 11.2	9.6
Patents and Trademarks [Member]
Intangible Assets Subject to Amortization [Abstract]
Weighted average useful life	19 years
Gross carrying amount	$ 6.4	6.4
Accumulated amortization	$ 6.4	6.1
Customer Relationships [Member]
Intangible Assets Subject to Amortization [Abstract]
Weighted average useful life	21 years
Gross carrying amount	$ 75.2	26.9
Accumulated amortization	$ 7.9	$ 5.9

Derivative Financial Instruments and Hedging Activities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) Subsidiary Contract	Dec. 31, 2020 USD ($) Contract	Dec. 31, 2019 USD ($)	Jul. 01, 2018 USD ($)
Derivative, Fair Value [Abstract]
(Gains) losses in other non-operating income (deductions)	$ (5.6)	$ 5.3	$ 8.2
Minimum [Member]
Derivative, Fair Value [Abstract]
Number of foreign subsidiaries in which portion of net investment is hedged \| Subsidiary	1
Foreign Exchange Forward [Member]
Derivative, Fair Value [Abstract]
Number of contracts \| Contract	0	0
(Gains) losses in other non-operating income (deductions)	$ 0.7	$ 0.2	$ 2.1
Cash Flow Hedges [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member]
Derivative, Fair Value [Abstract]
Notional amount				$ 150.0
Cash Flow Hedges [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Swap [Member] \| Other Non-Current Liabilities [Member]
Derivative, Fair Value [Abstract]
Fair value of derivative liability	4.0
Net Investment Hedge [Member] \| Designated as Hedging Instrument [Member] \| Cross Currency Rate Swap [Member]
Derivative, Fair Value [Abstract]
Notional amount				$ 150.0
Net Investment Hedge [Member] \| Designated as Hedging Instrument [Member] \| Cross Currency Rate Swap [Member] \| Other Assets and Deferred Charges [Member]
Derivative, Fair Value [Abstract]
Fair value of derivative asset	$ 8.2

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Additional Fair Value Elements [Abstract]
Transfers in or out of Level 3	$ 0.0	$ 0.0
Fair Value, Measurements, Recurring [Member]
Additional Fair Value Elements [Abstract]
Deferred compensation plan assets	14.6	14.2
Supplementary pension plan assets	16.8	15.0
Cross currency rate swap	8.2	0.4
Interest rate swaps	(4.0)	(7.6)
Fair Value, Measurements, Recurring [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Additional Fair Value Elements [Abstract]
Deferred compensation plan assets	0.0	0.0
Supplementary pension plan assets	0.0	0.0
Cross currency rate swap	0.0	0.0
Interest rate swaps	0.0	0.0
Fair Value, Measurements, Recurring [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Additional Fair Value Elements [Abstract]
Deferred compensation plan assets	14.6	14.2
Supplementary pension plan assets	16.8	15.0
Cross currency rate swap	8.2	0.4
Interest rate swaps	(4.0)	(7.6)
Fair Value, Measurements, Recurring [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Additional Fair Value Elements [Abstract]
Deferred compensation plan assets	0.0	0.0
Supplementary pension plan assets	0.0	0.0
Cross currency rate swap	0.0	0.0
Interest rate swaps	$ 0.0	$ 0.0

Financial Instruments and Concentrations of Credit Risk (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financial Instruments and Concentrations of Credit Risk [Abstract]
Bad debt expense	$ 0.9	$ 2.6	$ 6.3

Long-Term Debt and Commitments, Summary of Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Feb. 14, 2017	Jun. 23, 2015
Long-Term Debt and Commitments [Abstract]
Total long-term debt	$ 937.0	$ 934.2
Less: Current maturities	0.8	1.0
Long-term debt	936.2	933.2
Term Loan Facility - Variable Tranche [Member]
Long-Term Debt and Commitments [Abstract]
Total long-term debt	$ 539.2	535.6	$ 788.0	$ 1,078.0
Maturity date	Feb. 14, 2024
Unamortized discount and deferred financing costs	$ 8.8	12.4
Senior Notes due 2028 [Member]
Long-Term Debt and Commitments [Abstract]
Total long-term debt	$ 394.6	393.9
Maturity date	Jun. 30, 2028
Unamortized deferred financing cost	$ 5.4
Netherlands Term Loan Due 2022 [Member]
Long-Term Debt and Commitments [Abstract]
Total long-term debt	$ 0.2	0.6
Maturity date	Dec. 31, 2022
Japan Loan Facilities [Member]
Long-Term Debt and Commitments [Abstract]
Total long-term debt	$ 3.0	$ 4.1

Long-Term Debt and Commitments, Long-Term Debt (Details) $ in Millions			3 Months Ended	12 Months Ended
	Apr. 30, 2018 USD ($)	Feb. 14, 2017 USD ($)	Oct. 03, 2021 Loan	Dec. 31, 2021 USD ($) qtr Offering Loan	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 23, 2015 USD ($)	May 09, 2014 USD ($)
Long-Term Debt and Commitments [Abstract]
Long-term debt				$ 937.0	$ 934.2
Repayments of long-term debt				1.2	290.1	$ 88.2
Short-term borrowings				$ 80.0	0.0
Weighted average interest rate on short-term borrowings				1.80%
Maturities of Long-term Debt [Abstract]
2022				$ 0.8
2023				0.6
2024				548.6
2025				0.6
2026				0.6
Thereafter				400.0
Interest Costs [Abstract]
Interest costs				42.1	40.7	46.0
Capitalized interest cost				1.5	0.6	$ 0.6
Sivomatic [Member]
Long-Term Debt and Commitments [Abstract]
Long-term debt assumed as part of acquisition	$ 10.7
Credit Agreement [Member]
Long-Term Debt and Commitments [Abstract]
Letters of credit excluded from financial covenant				$ 25.0
Number of quarters to maintain net leverage ratio under financial covenant \| qtr				4
Credit Agreement [Member] \| Maximum [Member]
Long-Term Debt and Commitments [Abstract]
Net leverage ratio				3.50
Term Facility [Member]
Long-Term Debt and Commitments [Abstract]
Face amount									$ 1,560.0
Long-term debt								$ 1,378.0
Term Loan Facility - Variable Tranche [Member]
Long-Term Debt and Commitments [Abstract]
Long-term debt		$ 788.0		$ 539.2	535.6			1,078.0
Decrease in basis spread on variable rate		(0.75%)
Maturity date				Feb. 14, 2024
Required annual amortization				1.00%
Term Loan Facility - Variable Tranche [Member] \| Minimum [Member]
Long-Term Debt and Commitments [Abstract]
Interest rate				0.75%
Term Loan Facility - Variable Tranche [Member] \| LIBOR [Member]
Long-Term Debt and Commitments [Abstract]
Basis spread on variable rate				2.25%
Term Loan Facility - Fixed Tranche [Member]
Long-Term Debt and Commitments [Abstract]
Long-term debt								$ 300.0
Revolving Facility [Member]
Long-Term Debt and Commitments [Abstract]
Maximum borrowing capacity				$ 300.0					$ 200.0
Long-term debt				$ 80.0
Maturity date				Apr. 18, 2023
Letters of credit outstanding				$ 10.6
Revolving Facility [Member] \| Maximum [Member]
Long-Term Debt and Commitments [Abstract]
Decrease in basis spread if net leverage ratio is less than certain thresholds				(0.25%)
Revolving Facility [Member] \| LIBOR [Member]
Long-Term Debt and Commitments [Abstract]
Basis spread on variable rate				1.625%
Senior Notes due 2028 [Member]
Long-Term Debt and Commitments [Abstract]
Face amount							$ 400.0
Long-term debt				$ 394.6	393.9
Maturity date				Jun. 30, 2028
Interest rate				5.00%
Guarantee amount				$ 50.0
Number of equity offerings where funds can be used to redeem percentage of aggregate principal amount \| Offering				1
Senior Notes due 2028 [Member] \| Redemption of Notes for Cash Prior to July 1, 2023 [Member]
Long-Term Debt and Commitments [Abstract]
Redemption price percentage				100.00%
Senior Notes due 2028 [Member] \| Redemption of Notes with Funds from One or More Equity Offerings Prior to July 1, 2023 [Member]
Long-Term Debt and Commitments [Abstract]
Redemption price percentage				105.00%
Percentage of aggregate principal amount that can be redeemed				40.00%
Senior Notes due 2028 [Member] \| Redemption of Notes if Company Experiences Change of Control [Member]
Long-Term Debt and Commitments [Abstract]
Redemption price percentage				101.00%
Netherlands Term Loans [Member]
Long-Term Debt and Commitments [Abstract]
Repayments of long-term debt				$ 0.4
Number of term loans \| Loan				2
Number of term loans that matured \| Loan			1
Netherlands Term Loans [Member] \| Euribor [Member]
Long-Term Debt and Commitments [Abstract]
Basis spread on variable rate			2.00%
Japan Loan Facilities [Member]
Long-Term Debt and Commitments [Abstract]
Long-term debt				$ 3.0	$ 4.1
Repayments of long-term debt				0.8
Uncommitted Short-Term Bank Credit Lines [Member]
Long-Term Debt and Commitments [Abstract]
Maximum borrowing capacity				25.9
Short-term borrowings				$ 0.0

Benefit Plans, Pension Obligation and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Benefit Plans [Abstract]
Employee vesting period for defined benefit plans	5 years
Employer Contributions [Abstract]
Maximum percentage of total benefit obligation represented by international pension plans	22.00%
Change in plan assets [Roll Forward]
Beginning fair value	$ 358.2
Ending fair value	381.3	$ 358.2
Pension Benefits [Member]
Change in benefit obligations [Roll Forward]
Beginning projected benefit obligation	534.3	484.4
Service cost	7.7	7.7	$ 6.8
Interest cost	7.9	10.5	14.0
Actuarial (gain)/loss	(23.8)	56.5
Benefits paid	(12.4)	(12.3)
Settlements	(16.3)	(18.4)
Foreign exchange impact	(2.7)	5.5
Other	0.3	0.4
Ending projected benefit obligation	495.0	534.3	484.4
Change in plan assets [Roll Forward]
Beginning fair value	358.2	340.0
Actual return on plan assets	44.0	31.1
Employer contributions	10.7	11.8
Plan participants' contributions	0.3	0.3
Benefits paid	(12.4)	(12.2)
Settlements	(17.1)	(16.9)
Foreign exchange impact	(2.3)	4.1
Ending fair value	381.4	358.2	340.0
Defined benefit plan, funded (unfunded) status of plan [Abstract]
Funded status	(113.6)	(176.1)
Post-Retirement Benefits [Member]
Change in benefit obligations [Roll Forward]
Beginning projected benefit obligation	4.6	5.9
Service cost	0.1	0.2	0.2
Interest cost	0.1	0.2	0.2
Actuarial (gain)/loss	(0.3)	(1.3)
Benefits paid	(0.5)	(0.4)
Settlements	(1.6)	0.0
Foreign exchange impact	(0.1)	0.0
Other	0.0	0.0
Ending projected benefit obligation	2.3	4.6	5.9
Change in plan assets [Roll Forward]
Beginning fair value	0.0	0.0
Actual return on plan assets	0.0	0.0
Employer contributions	0.5	0.4
Plan participants' contributions	0.0	0.0
Benefits paid	(0.5)	(0.4)
Settlements	0.0	0.0
Foreign exchange impact	0.0	0.0
Ending fair value	0.0	0.0	$ 0.0
Defined benefit plan, funded (unfunded) status of plan [Abstract]
Funded status	$ (2.3)	$ (4.6)

Benefit Plans, Amounts Recognized in Consolidated Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Amounts recognized in Balance Sheet [Abstract]
Current liability	$ (57.9)	$ (60.3)
Non-current liability	(114.3)	(179.0)
Pension Benefits [Member]
Amounts recognized in Balance Sheet [Abstract]
Current liability	(1.4)	(1.4)
Non-current liability	(112.2)	(174.7)
Recognized liability	(113.6)	(176.1)
Post-Retirement Benefits [Member]
Amounts recognized in Balance Sheet [Abstract]
Current liability	(0.2)	(0.3)
Non-current liability	(2.1)	(4.3)
Recognized liability	$ (2.3)	$ (4.6)

Benefit Plans, Amounts Recognized in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Amounts recognized in accumulated other comprehensive income [Abstract]
Amount recognized end of year	$ 69.6	$ 114.9
Accumulated benefit obligation	408.7	501.7
Pension Benefits [Member]
Amounts recognized in accumulated other comprehensive income [Abstract]
Net actuarial (gain) loss	73.2	119.0
Prior service cost	0.1	0.1
Amount recognized end of year	73.3	119.1
Post-Retirement Benefits [Member]
Amounts recognized in accumulated other comprehensive income [Abstract]
Net actuarial (gain) loss	(3.7)	(4.2)
Prior service cost	0.0	0.0
Amount recognized end of year	$ (3.7)	$ (4.2)

Benefit Plans, Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Changes in Plan assets and benefit obligations recognized in other comprehensive income [Abstract]
Amortization of prior service credit (gain) loss	$ (8.4)	$ (10.0)	$ (7.1)
Total recognized in other comprehensive income	(45.2)	18.7	$ 16.1
Pension Benefits [Member]
Changes in Plan assets and benefit obligations recognized in other comprehensive income [Abstract]
Current year actuarial gain (loss)	36.7	(29.6)
Amortization of actuarial (gain) loss	9.0	10.5
Amortization of prior service credit (gain) loss	0.0	0.0
Total recognized in other comprehensive income	45.7	(19.1)
Post-Retirement Benefits [Member]
Changes in Plan assets and benefit obligations recognized in other comprehensive income [Abstract]
Current year actuarial gain (loss)	0.1	0.9
Amortization of actuarial (gain) loss	(0.6)	(0.5)
Amortization of prior service credit (gain) loss	0.0	0.0
Total recognized in other comprehensive income	$ (0.5)	$ 0.4

Benefit Plans, Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	$ 7.7	$ 7.7	$ 6.8
Interest cost	7.9	10.5	14.0
Expected return on plan assets	(22.0)	(20.1)	(18.2)
Amortization of prior service cost	0.0	0.0	0.0
Recognized net actuarial (gain) loss	12.1	13.9	10.1
Settlement/curtailment (gain) loss	3.4	6.4	(0.1)
Net periodic benefit cost	9.1	18.4	12.6
Post-Retirement Benefits [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost	0.1	0.2	0.2
Interest cost	0.1	0.2	0.2
Expected return on plan assets	0.0	0.0	0.0
Amortization of prior service cost	0.0	0.0	0.0
Recognized net actuarial (gain) loss	(0.8)	(0.9)	(0.9)
Settlement/curtailment (gain) loss	(1.6)	0.0	0.0
Net periodic benefit cost	$ (2.2)	$ (0.5)	$ (0.5)

Benefit Plans, Weighted Average Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Weighted average assumptions used to determine net periodic benefit cost [Abstract]
Discount rate	2.01%	2.74%	3.75%
Expected return on plan assets	6.28%	6.32%	6.43%
Rate of compensation increase	2.72%	2.72%	3.01%
Interest crediting rate	2.25%	3.75%	2.57%
Weighted average assumptions used to determine benefit obligation [Abstract]
Discount rate	2.42%	2.01%	2.75%
Rate of compensation increase	2.74%	2.98%	2.99%
Actual return (loss) on pension assets	12.00%	9.00%	15.00%
Maximum health care cost trend rate	5.00%

Benefit Plans, Weighted Average Asset Allocation Percentages (Details)	Dec. 31, 2021	Dec. 31, 2020
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentage	100.00%	100.00%
Equity Securities [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentage	54.20%	55.80%
Fixed Income Securities [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentage	30.60%	27.80%
Real Estate [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentage	0.30%	0.30%
Other [Member]
Weighted average asset allocations [Abstract]
Weighted average asset allocation percentage	14.90%	16.10%

Benefit Plans, Fair Values by Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Weighted average asset allocations value [Abstract]
Fair value of plan assets	$ 381.3	$ 358.2
Equity Securities [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	206.7	200.0
Fixed Income Securities [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	116.5	99.7
Real Estate [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	1.0	1.0
Other [Member]
Weighted average asset allocations value [Abstract]
Fair value of plan assets	$ 57.1	$ 57.5

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References + Details

Benefit Plans, Defined Benefit Pension Plan Assets Measured at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair value of plan assets [Abstract]
Fair value of plan assets	$ 381.3	$ 358.2
U.S. Plans [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	293.7	271.6	$ 261.5
International Plans [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	87.6	86.6	$ 78.5
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	303.5	280.7
Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	71.8	69.2
Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	6.0	8.3
Equity Securities [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	206.7	200.0
US Equities [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	182.7	182.0
US Equities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	182.7	182.0
US Equities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
US Equities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Non-US Equities [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	24.0	18.0
Non-US Equities [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	24.0	18.0
Non-US Equities [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Non-US Equities [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Fixed Income Securities [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	116.5	99.7
Corporate Debt Instruments [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	116.5	99.7
Corporate Debt Instruments [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	96.4	80.4
Corporate Debt Instruments [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	20.1	19.3
Corporate Debt Instruments [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Real Estate [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	1.0	1.0
Real Estate [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Real Estate [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.0	0.0
Real Estate [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	1.0	1.0
Other [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	57.1	57.5
Other [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	0.4	0.3
Other [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	51.7	49.9
Other [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Fair value of plan assets [Abstract]
Fair value of plan assets	$ 5.0	$ 7.3

Benefit Plans, Reconciliation of Changes in Fair Value Measurement of Plan Assets Using Significant Unobservable Inputs (Details) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Reconciliation of changes in fair value measurement of plan assets [Roll Forward]
Beginning balance	$ 8.3	$ 21.0
Purchases, sales, settlements	0.0	0.0
Actual return on plan assets still held at reporting date	(2.3)	(12.8)
Foreign exchange impact	0.0	0.1
Ending balance	6.0	8.3
Fair Value Transfers [Abstract]
Fair value, assets, Level 3 transfers in, amount	0.0	0.0
Fair value, assets, Level 3 transfers out, amount	$ 0.0	$ 0.0

Benefit Plans, Contributions (Details) $ in Millions	Dec. 31, 2021 USD ($)
Pension Benefits [Member]
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Expected company contribution in 2021	$ 10.1
Post-Retirement Benefits [Member]
Defined Benefit Plan, Expected Future Employer Contributions [Abstract]
Expected company contribution in 2021	$ 0.5

Benefit Plans, Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2021 USD ($)
Pension Benefits [Member]
Estimated future benefit payments [Abstract]
2022	$ 24.1
2023	25.9
2024	26.3
2025	26.1
2026	26.6
2027-2031	130.0
Post-Retirement Benefits [Member]
Estimated future benefit payments [Abstract]
2022	0.2
2023	0.2
2024	0.2
2025	0.2
2026	0.2
2027-2031	$ 0.8

Benefit Plans, Investment Strategies (Details)	12 Months Ended
Benefit Plans, Investment Strategies (Details)	Dec. 31, 2021
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Average rate of return on assets	10.00%
Equity Securities [Member] \| Minimum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	55.00%
Equity Securities [Member] \| Maximum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	65.00%
Fixed Income Securities [Member] \| Minimum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	30.00%
Fixed Income Securities [Member] \| Maximum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	35.00%
Other Securities [Member] \| Minimum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	0.00%
Other Securities [Member] \| Maximum [Member]
Defined Benefit Plan, Plan Assets, Allocations [Abstract]
Target long-term investment portfolio mix	15.00%

Benefit Plans, Savings and Investment Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Benefit Plans [Abstract]
Company's contributions to employee voluntary savings and investment plan	$ 5.3	$ 5.2	$ 5.4

Contingencies (Details)	12 Months Ended
Contingencies (Details)	Dec. 31, 2021 Case
Silica Cases [Member]
Contingencies [Abstract]
Number of lawsuits settled	1
Asbestos Cases [Member]
Contingencies [Abstract]
Number of lawsuits settled	0

Stockholders' Equity, Capital Stock and Cash Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 31, 2022
Capital Stock [Abstract]
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares outstanding (in shares)	33,177,193	33,882,187
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Cash Dividends [Abstract]
Cash dividends paid	$ 6.8	$ 6.8	$ 7.0
Cash dividends paid (in dollars per share)	$ 0.20
Subsequent Event [Member] \| Dividend Declared 2022-Q1 [Member]
Cash Dividends [Abstract]
Cash dividend declared				$ 1.7
Cash dividend declared (in dollars per share)				$ 0.05

Stockholders' Equity, Stock Award and Incentive Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Shares Available for Grant [Roll Forward]
Balance, beginning of year (in shares)	1,532,246	529,042	866,023
Authorized (in shares)		1,300,000
Granted (in shares)	(358,078)	(394,290)	(388,162)
Exercised/vested (in shares)	0	0	0
Canceled (in shares)	94,602	97,494	51,181
Balance, end of year (in shares)	1,268,770	1,532,246	529,042
Stock Options [Member]
Stock Award and Incentive Plan [Abstract]
Term of stock options granted under Plan	10 years
Vesting period	3 years
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	1,363,366	1,227,620	1,054,259
Granted (in shares)	255,769	286,078	271,261
Exercised/vested (in shares)	(251,195)	(93,099)	(79,686)
Canceled (in shares)	(37,938)	(57,233)	(18,214)
Balance, end of year (in shares)	1,330,002	1,363,366	1,227,620
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 57.29	$ 55.83	$ 54.04
Granted (in dollars per share)	66.00	57.67	54.44
Exercised/vested (in dollars per share)	51.12	35.11	27.26
Canceled (in dollars per share)	64.92	63.92	66.93
Balance, end of year (in dollars per share)	$ 59.91	$ 57.29	$ 55.83
Restricted Stock [Member]
Restricted Stock [Roll Forward]
Balance, beginning of year (in shares)	201,985	177,736	134,578
Granted (in shares)	102,309	108,212	116,901
Exercised/vested (in shares)	(51,497)	(43,702)	(40,776)
Canceled (in shares)	(56,664)	(40,261)	(32,967)
Balance, end of year (in shares)	196,133	201,985	177,736
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 58.07	$ 62.40	$ 68.64
Granted (in dollars per share)	66.20	56.93	54.51
Exercised/vested (in dollars per share)	60.40	66.07	60.79
Canceled (in dollars per share)	60.98	65.42	61.87
Balance, end of year (in dollars per share)	$ 60.87	$ 58.07	$ 62.40

Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Cumulative foreign currency translation	$ (269.8)	$ (190.8)
Unrecognized pension costs (net of tax benefit of $21.4 in 2021 and $64.6 in 2020)	(69.6)	(114.9)
Unrealized gain (loss) on cash flow hedges (net of tax expense (benefit) of $3.0 in 2021 and $(3.1) in 2020)	5.8	(2.6)
Total accumulated other comprehensive income (loss)	(333.6)	(308.3)
Unrecognized pension costs, tax benefit	21.4	64.6
Unrealized gain (loss) on cash flow hedges, tax expense (benefit)	3.0	(3.1)
Foreign currency translation adjustment [Abstract]
Foreign currency translation adjustment, pre-tax amount	(78.9)	10.9	$ (29.9)
Foreign currency translation adjustment, tax (expense) benefit	0.0	0.0	0.0
Foreign currency translation adjustments, net-of-tax amount	(78.9)	10.9	(29.9)
Pension plans [Abstract]
Net actuarial gains (losses) and prior service costs arising during the period, pre-tax amount	49.3	(37.9)	(30.6)
Net actuarial gains (losses) and prior service costs arising during the period, tax (expense) benefit	(12.5)	9.2	7.4
Net actuarial gains (losses) and prior service costs arising during the period, net-of-tax amount	36.8	(28.7)	(23.2)
Amortization of net actuarial (gains) losses and prior service costs, pre-tax amount	11.3	13.4	9.4
Amortization of net actuarial (gains) losses and prior service costs, tax (expense) benefit	(2.9)	(3.4)	(2.3)
Amortization of net actuarial (gains) losses and prior service costs, net-of-tax amount	8.4	10.0	7.1
Unrealized gains (losses) on cash flow hedges [Abstract]
Unrealized gains (losses) on cash flow hedges, pre-tax amount	11.4	(11.6)	0.3
Unrealized gains (losses) on cash flow hedges, tax (expense) benefit	(3.0)	3.1	(0.1)
Unrealized gains (losses) on cash flow hedges, net-of-tax amount	8.4	(8.5)	0.2
Total other comprehensive income (loss), pre-tax amount	(6.9)	(25.2)	(50.8)
Total other comprehensive income (loss), tax	(18.4)	8.9	5.0
Total other comprehensive income (loss), net of tax	$ (25.3)	$ (16.3)	$ (45.8)

Accounting for Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Asset retirement obligation [Roll Forward]
Asset retirement obligation, beginning of period	$ 24.1	$ 23.9
Accretion expense	1.9	2.3
Other	1.2	1.1
Payments	(2.3)	(3.4)
Foreign currency translation	(0.5)	0.2
Asset retirement obligation, end of period	24.4	$ 24.1
Asset retirement obligation [Abstract]
Asset retirement obligation, current portion	0.7
Asset retirement obligation, noncurrent portion	$ 23.7

Segment and Related Information, Segment Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) Segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Segment and Related Information [Abstract]
Number of reportable segments \| Segment	3
Segment Reporting Information [Abstract]
Net sales	$ 1,858.3	$ 1,594.8	$ 1,791.0
Income from operations	235.7	187.9	208.7
Depreciation, depletion and amortization	94.6	93.9	98.4
Segment assets	3,374.2	3,209.4	3,112.6
Capital expenditures	86.0	66.8	65.0
Segment and Related Information [Abstract]
Litigation expenses	0.0	(10.4)	(10.9)
Acquisition-related expenses	(4.0)	(3.1)	0.0
Unallocated corporate expenses	(7.5)	(10.7)	(8.2)
Consolidated income from operations	235.7	187.9	208.7
Non-operating deductions, net	(33.4)	(49.9)	(51.4)
Income from operations before provision for taxes and equity in earnings	202.3	138.0	157.3
Performance Materials [Member]
Segment Reporting Information [Abstract]
Net sales	976.0	825.8	918.5
Specialty Minerals [Member]
Segment Reporting Information [Abstract]
Net sales	578.9	510.9	574.4
Refractories [Member]
Segment Reporting Information [Abstract]
Net sales	303.4	258.1	298.1
Reportable Segments [Member]
Segment Reporting Information [Abstract]
Net sales	1,858.3	1,594.8	1,791.0
Income from operations	247.2	212.1	227.8
Depreciation, depletion and amortization	94.6	93.9	98.4
Segment assets	3,292.2	3,069.5	3,031.0
Capital expenditures	83.4	66.6	64.9
Segment and Related Information [Abstract]
Consolidated income from operations	247.2	212.1	227.8
Reportable Segments [Member] \| Performance Materials [Member]
Segment Reporting Information [Abstract]
Net sales	976.0	825.8	918.5
Income from operations	125.0	108.8	104.9
Depreciation, depletion and amortization	49.2	47.4	51.0
Segment assets	2,393.2	2,219.1	2,212.7
Capital expenditures	22.0	14.6	21.5
Segment and Related Information [Abstract]
Consolidated income from operations	125.0	108.8	104.9
Reportable Segments [Member] \| Specialty Minerals [Member]
Segment Reporting Information [Abstract]
Net sales	578.9	510.9	574.4
Income from operations	72.9	67.8	83.1
Depreciation, depletion and amortization	38.4	39.6	40.4
Segment assets	605.9	559.6	525.1
Capital expenditures	51.7	46.5	37.7
Segment and Related Information [Abstract]
Consolidated income from operations	72.9	67.8	83.1
Reportable Segments [Member] \| Refractories [Member]
Segment Reporting Information [Abstract]
Net sales	303.4	258.1	298.1
Income from operations	49.3	35.5	39.8
Depreciation, depletion and amortization	7.0	6.9	7.0
Segment assets	293.1	290.8	293.2
Capital expenditures	9.7	5.5	5.7
Segment and Related Information [Abstract]
Consolidated income from operations	49.3	35.5	39.8
Unallocated and Other Corporate Expenses [Member]
Segment Reporting Information [Abstract]
Segment assets	82.0	139.9	81.6
Capital expenditures	$ 2.6	$ 0.2	$ 0.1

Segment and Related Information, Financial Information Related to Operations by Geographic Area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Abstract]
Net sales	$ 1,858.3	$ 1,594.8	$ 1,791.0
Long-lived assets	2,207.6	2,043.9	2,063.2
Total International [Member]
Segment Reporting Information [Abstract]
Net sales	898.7	772.3	828.6
Long-lived assets	282.3	320.7	320.9
Reportable Geographical Components [Member] \| United States [Member]
Segment Reporting Information [Abstract]
Net sales	959.6	822.5	962.4
Long-lived assets	1,925.3	1,723.2	1,742.3
Reportable Geographical Components [Member] \| Canada/Latin America [Member]
Segment Reporting Information [Abstract]
Net sales	99.8	70.5	80.2
Long-lived assets	10.6	11.3	13.0
Reportable Geographical Components [Member] \| Europe/Africa [Member]
Segment Reporting Information [Abstract]
Net sales	441.9	410.0	435.3
Long-lived assets	151.1	182.9	190.7
Reportable Geographical Components [Member] \| Asia [Member]
Segment Reporting Information [Abstract]
Net sales	357.0	291.8	313.1
Long-lived assets	$ 120.6	$ 126.5	$ 117.2

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Segment and Related Information, Sales by Product Category (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment and Related Information [Abstract]
Net sales	$ 1,858.3	$ 1,594.8	$ 1,791.0
Household, Personal Care & Specialty Products [Member]
Segment and Related Information [Abstract]
Net sales	460.5	380.2	376.6
Metalcasting [Member]
Segment and Related Information [Abstract]
Net sales	319.2	258.1	291.2
Environmental Products [Member]
Segment and Related Information [Abstract]
Net sales	136.3	131.6	181.8
Building Materials [Member]
Segment and Related Information [Abstract]
Net sales	60.0	55.9	68.9
Paper PCC [Member]
Segment and Related Information [Abstract]
Net sales	349.7	308.4	364.9
Specialty PCC [Member]
Segment and Related Information [Abstract]
Net sales	77.1	69.3	69.1
Ground Calcium Carbonate [Member]
Segment and Related Information [Abstract]
Net sales	98.1	89.3	91.3
Talc [Member]
Segment and Related Information [Abstract]
Net sales	54.0	43.9	49.1
Refractory Products [Member]
Segment and Related Information [Abstract]
Net sales	237.1	212.3	244.8
Metallurgical Products [Member]
Segment and Related Information [Abstract]
Net sales	$ 66.3	$ 45.8	$ 53.3