W.R. Grace & Co. (GRA) 10-K 26 Feb 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Document and Entity Information [Abstract]
Entity Central Index Key	0001045309
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	1-13953
Entity Registrant Name	W. R. GRACE & CO.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	65-0773649
Entity Address, Address Line One	7500 Grace Drive
Entity Address, City or Town	Columbia
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	21044-4098
City Area Code	(410)
Local Phone Number	531-4000
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	GRA
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2,844,898,340
Entity Common Stock, Shares Outstanding		66,191,426
Document Information [Line Items]
ICFR Auditor Attestation Flag	true

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 1,729.8	$ 1,958.1	$ 1,932.1
Cost of goods sold	1,113.3	1,164.4	1,165.4
Gross profit	616.5	793.7	766.7
Selling, general and administrative expenses	282.9	299	300.4
Research and development expenses	65.9	64.5	62.7
Costs related to legacy matters	39.4	103.5	82.3
Restructuring and repositioning expenses	36.9	13.7	46.4
Equity in earnings of unconsolidated affiliate	(13.5)	(27.8)	(31.8)
Loss on early extinguishment of debt	39.4	0	4.8
Interest and Debt Expense Excluding Loss on Debt Extinguishment	76	76.7	80.2
Nonoperating Income (Expense)	89	80.6	(23.2)
Total costs and expenses	616	610.2	521.8
Income (loss) before income taxes	0.5	183.5	244.9
(Provision for) benefit from income taxes	(2.2)	(56.8)	(78.1)
Net income (loss)	(1.7)	126.7	166.8
Less: Net (income) loss attributable to noncontrolling interests	(0.1)	(0.4)	0.8
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ (1.8)	$ 126.3	$ 167.6
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss)	$ (0.03)	$ 1.89	$ 2.49
Weighted average number of basic shares	66.3	66.8	67.2
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss)	$ (0.03)	$ 1.89	$ 2.49
Weighted average number of diluted shares	66.3	66.9	67.3
Dividends per common share	$ 1.20	$ 1.08	$ 0.96

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income (loss)	$ (1.7)	$ 126.7	$ 166.8
Other comprehensive income (loss):
Defined benefit pension and other postretirement plans	(0.4)	(0.7)	(0.9)
Currency translation adjustments	(49.9)	16.5	32.4
Gain (loss) from hedging activities	0.8	(4.9)	(5.7)
Total other comprehensive income (loss), net of income taxes	(49.5)	10.9	25.8
Comprehensive income (loss)	(51.2)	137.6	192.6
Less: comprehensive (income) loss attributable to noncontrolling interests	(0.1)	(0.4)	0.8
Comprehensive income (loss) attributable to W. R. Grace & Co. shareholders	$ (51.3)	$ 137.2	$ 193.4

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income (loss)	$ (1.7)	$ 126.7	$ 166.8
Reconciliation to net cash provided by operating activities:
Depreciation and amortization	105	100.3	100.8
Equity in earnings of unconsolidated affiliate	(13.5)	(27.8)	(31.8)
Dividends received from unconsolidated affiliate	20	0	0
Costs related to legacy matters	39.4	103.5	82.3
Cash paid for legacy matters	(21)	(19.3)	(22.9)
Provision for (benefit from) income taxes	2.2	56.8	78.1
Income Taxes Paid	(56)	(52.8)	(54)
Proceeds from Income Tax Refunds	9.6	10.5	0.7
Defined benefit pension expense (income)	109	104.3	0.7
Cash paid under defined benefit pension arrangements	(17.2)	(15.8)	(66.5)
Share-based Payment Arrangement, Noncash Expense	10.7	14.6	18.6
Loss on early extinguishment of debt	39.4	0	4.8
Gain (Loss) on Disposition of Assets	23.2	4.2	13.2
Changes in assets and liabilities, excluding effect of currency translation:
Trade accounts receivable	59.7	(18.7)	2.5
Inventories	62	(30.1)	(26.1)
Accounts payable	(9.3)	28	24.2
Increase (Decrease) in Contract with Customer, Liability	(7.4)	(5.3)	35.6
All other items, net	(4.5)	13	15
Net Cash Provided by (Used in) Operating Activities	349.6	392.1	342
INVESTING ACTIVITIES
Capital expenditures	(155.5)	(194.1)	(216.3)
Business acquired, net of cash acquired	(2)	(22.8)	(418)
Other investing activities	(18.3)	6.8	15.8
Net Cash Provided by (Used in) Investing Activities	(175.8)	(210.1)	(618.5)
FINANCING ACTIVITIES
Borrowings under credit arrangements	15.9	13	1,024
Repayments of Debt and Lease Obligation	(49.9)	(24.2)	(587.8)
Proceeds from Issuance of Unsecured Debt	750	0	0
Repayments of Long-term Debt	(700)	0	0
Payment for Debt Extinguishment or Debt Prepayment Cost	(37.9)	0	0
Payments of Debt Issuance Costs	(7.9)	0	(11.8)
Cash paid for repurchases of common stock	(40.4)	(29.8)	(80)
Proceeds from exercise of stock options	0	19.1	6.7
Dividends paid to shareholders	(80.1)	(72.6)	(64.6)
Proceeds from Hedge, Financing Activities	0	0	33.1
Other financing activities	(7.6)	(4.9)	(3.1)
Net Cash Provided by (Used in) Financing Activities	(157.9)	(99.4)	316.5
Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations	7.4	(0.7)	(2.5)
Cash flows from discontinued operations
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	23.3	81.9	37.5
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	282.9	201	163.5
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	306.2	282.9	201
Supplemental disclosure of cash flow information
Interest Paid, Excluding Capitalized Interest, Operating Activities	74.2	67.7	75.2
Capital expenditures included in accounts payable	51.9	49.8	31
Expenditures for other investing activities included in accounts payable	0.4	16.2	16.9
Net share settled stock option exercises	$ 0	$ 9.7	$ 8.2

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current Assets
Cash and cash equivalents	$ 304.5	$ 282.5
Restricted cash and cash equivalents	1.7	0.4
Accounts Receivable, after Allowance for Credit Loss, Current	264.1	307
Inventories	253.8	309.9
Other current assets	51.2	235.1
Total Current Assets	875.3	1,134.9
Properties and equipment, net	1,208.8	1,143.8
Goodwill	562.7	556.9
Technology and other intangible assets, net	320.8	342.8
Deferred Income Tax Assets, Net	567.1	517.6
Investment in unconsolidated affiliate	175.5	181.9
Other assets	55.3	54.7
Total Assets	3,765.5	3,932.6
Current Liabilities
Debt payable within one year	15.3	23.1
Accounts payable	262.1	302.3
Other current liabilities	281.9	419.7
Total Current Liabilities	559.3	745.1
Debt payable after one year	1,975.1	1,957.3
Defined Benefit Pension Plan Liabilities Noncurrent Unfunded	520.7	434.6
Defined Benefit Pension Plan Liabilities Noncurrent Underfunded	128.3	85.2
Other liabilities	347.6	308.2
Liabilities, Total	3,531	3,530.4
Commitments and Contingencies
Common stock issued, shares outstanding	66,190,410	66,735,913
Common stock issued, shares authorized	300,000,000	300,000,000
Par value of common stock (in dollars per share)	$ 0.01	$ 0.01
Equity
Common Stock, Value, Outstanding	$ 0.7	$ 0.7
Additional Paid in Capital, Common Stock	473.2	477.9
Retained Earnings (Accumulated Deficit)	$ 648.8	$ 730.5
Treasury Stock, Shares	11,266,223	10,720,720
Treasury Stock, Value	$ (920.6)	$ (892.2)
Accumulated Other Comprehensive Income (Loss), Net of Tax	29.3	78.8
Stockholders' Equity Attributable to Parent, Total	231.4	395.7
Stockholders' Equity Attributable to Noncontrolling Interest	3.1	6.5
Total Equity	234.5	402.2
Total Liabilities and Equity	$ 3,765.5	$ 3,932.6

Consolidated Statements of Equi

Consolidated Statements of Equity Statement - USD ($) $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, AdjustmentDifference between Revenue Guidance in Effect before and after Topic 606 [Member]	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings [Member]Cumulative Effect, Period of Adoption, AdjustmentDifference between Revenue Guidance in Effect before and after Topic 606 [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	AOCI Attributable to Parent [Member]Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2017	$ 263.3			$ 475.5	$ 573.1			$ (832.1)	$ 39.9		$ 6.9
Net income (loss)	166.8				167.6						(0.8)
Treasury Stock, Value, Acquired, Cost Method	80							80
Stock-based compensation	18.6			18.6
Exercise of stock options	6.4			(4.2)				10.6
Adjustment to Additional Paid In Capital, Tax Payments Related to Stock-based Compensation	(2.9)			(2.9)
Shares issued	0.8			(5.2)				6
Dividends declared	(64.3)				(64.3)
Other comprehensive income (loss)	25.8								25.8
Other comprehensive income (loss)	0
Ending Balance at Dec. 31, 2018	337		$ 2.5	481.8	676.7		$ 2.5	(895.5)	67.9		6.1
Ending Balance (Accounting Standards Update 2018-02 [Member]) at Dec. 31, 2018									2.2
Ending Balance (Accounting Standards Update 2018-12) at Dec. 31, 2018		$ 0				$ (2.2)				$ 2.2
Net income (loss)	126.7				126.3						0.4
Treasury Stock, Value, Acquired, Cost Method	29.8							29.8
Stock-based compensation	14.6			14.6
Exercise of stock options	19.1			(5)				24.1
Adjustment to Additional Paid In Capital, Tax Payments Related to Stock-based Compensation	(4.9)			(4.9)
Shares issued	1.1			(7.9)				9
Dividends declared	(72.5)				(72.5)
Other comprehensive income (loss)	10.9								10.9
Other comprehensive income (loss)	0
Ending Balance at Dec. 31, 2019	402.2			478.6	730.5			(892.2)	78.8		6.5
Net income (loss)	(1.7)				(1.8)						0.1
Treasury Stock, Value, Acquired, Cost Method	40.4							40.4
Stock-based compensation	10.5			10.5
Adjustment to Additional Paid In Capital, Tax Payments Related to Stock-based Compensation	(4)			(4)
Shares issued	0.8			(11.2)				12
Dividends declared	(79.9)				(79.9)
Payments to Acquire Interest in Joint Venture	(3.5)
Other comprehensive income (loss)	(49.5)								(49.5)
Other comprehensive income (loss)	0
Ending Balance at Dec. 31, 2020	$ 234.5			$ 473.9	$ 648.8			$ (920.6)	$ 29.3		$ 3.1

Consolidated Balance Sheet Pare

Consolidated Balance Sheet Parenthetical Details - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Properties and equipment, accumulated depreciation and amortization	$ 1,550.1	$ 1,497
Accounts Receivable, Allowance for Credit Loss, Current	$ 2.2	$ 13.3

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies	W. R. Grace & Co., through its subsidiaries, is engaged in the production and sale of specialty chemicals and specialty materials on a global basis through two reportable segments: Grace Catalysts Technologies, which includes catalysts and related products and technologies used in petrochemical, refining, and other chemical manufacturing applications; and Grace Materials Technologies, which includes specialty materials, including silica-based and silica-alumina-based materials, used in pharma/consumer, coatings, and chemical process applications. W. R. Grace & Co. conducts all of its business through a single wholly owned subsidiary, W. R. Grace & Co.–Conn. (“Grace–Conn.”). Grace–Conn. owns all of the assets, properties and rights of W. R. Grace & Co. on a consolidated basis, either directly or through subsidiaries. As used in these notes, the term “Company” refers to W. R. Grace & Co. The term “Grace” refers to the Company and/or one or more of its subsidiaries and, in certain cases, their respective predecessors. Principles of Consolidation The Consolidated Financial Statements include the accounts of Grace and entities as to which Grace maintains a controlling financial interest. Intercompany transactions and balances are eliminated in consolidation. Investments in affiliated companies in which Grace can significantly influence operating and financial policies, but does not have a controlling financial interest, are accounted for under the equity method. Grace conducts a portion of its business through joint ventures with unaffiliated third parties. For joint ventures in which Grace has a controlling financial interest, Grace consolidates the results of such joint ventures in the Consolidated Financial Statements. Grace recognizes a liability for cumulative amounts due to the third parties based on the financial results of the joint ventures, and deducts the amount of income attributable to noncontrolling interests in the measurement of its consolidated net income. Reportable Segments Grace reports financial results of each of its reportable segments that engage in business activities that generate revenues and expenses and whose operating results are regularly reviewed by Grace’s Chief Executive Officer. Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace’s accounting measurements that are most affected by management’s estimates of future events are: • The effective tax rate and realization values of net deferred tax assets, which depend on projections of future taxable income (see Note 7); • Pension and postretirement liabilities, which depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 8); • Carrying values of goodwill and other intangible assets, which depend on assumptions of future earnings and cash flows (see Note 4 and Note 20); and • Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate obligation, such as litigation and arbitration; and product, environmental, and other legacy liabilities (see Note 10). Revenue Recognition Grace generates revenues predominantly from sales of manufactured products to customers and in part from licensing of technology. Under ASC 606, revenue from customer arrangements is recognized when control is transferred to the customer. Product Sales Based on the promises made to customers in product sales arrangements, Grace has a performance obligation to manufacture and deliver products to its customers. Grace makes certain other promises in its customer arrangements that are immaterial in the context of the contracts. Revenue is recognized at amounts based on agreed-upon prices in sales contracts and/or purchase orders. Grace offers various incentives to its product sales customers that result in variable consideration, including but not limited to volume discounts, which reward bulk purchases by lowering the price for future purchases, and volume rebates, which encourage customers to purchase volume levels that would reduce their current prices. These incentives are immaterial in the context of the contracts. For product sales, control is transferred at the point in time at which risk of loss and title have transferred to the customer, which is determined based on shipping terms and contract terms, respectively. Terms of delivery and terms of payment are generally included in customer contracts of sale, order confirmation documents, and invoices. Payment is generally due within 30 to 60 days of invoicing. Grace defers revenue recognition until no other significant Grace performance obligations remain. Grace’s customer arrangements do not contain significant acceptance provisions. Taxes that Grace collects that are assessed by a governmental authority, and that are both imposed on and concurrent with any of its revenue-producing activities, are excluded from revenue. Grace considers shipping and handling activities that it performs as activities to fulfill the sales of its products. Amounts billed for shipping and handling are included in “net sales,” while costs incurred for shipping and handling are included in “cost of goods sold.” Technology Licensing For Grace’s technology licensing business, customer arrangements typically contain multiple deliverables to enable licensees to realize the full benefit of the technology. These deliverables include licensing the technology itself; developing engineering design packages; and providing training, consulting, and technical services. Under these arrangements, the license grant is not a distinct performance obligation, as the licensee only can benefit from the license in conjunction with other integral services such as development of the engineering design package, training, consulting, or technical services provided over the contract period. Therefore, Grace accounts for the license grant and integral services as a single performance obligation. Certain deliverables and services not included in the core bundled deliverables are accounted for as separate performance obligations. The transaction price is specified in the technology licensing agreements and is substantially fixed. Some services are priced on a per-diem basis, but these are not material in the context of the contracts. Grace invoices its technology licensing customers as certain project milestones are achieved. Payment terms are similar to those of Grace’s product sales. Revenue for each performance obligation is recognized when control is transferred to the customer, which is typically over a period of time. As a result, Grace generally recognizes revenue for each performance obligation ratably over the period of the contract, which is up to eight years, depending on the scope of the licensee’s project. Based on the timing of payments, Grace records deferred revenue related to these agreements. See Note 17. Cash Equivalents Cash equivalents consist of liquid instruments and investments with maturities of three months or less when purchased. The recorded amounts approximate fair value. Inventories Inventories are stated at the lower of cost or net realizable value. The method used to determine cost is first-in/first-out, or “FIFO.” Market values for raw materials are based on current cost and, for other inventory classifications, net realizable value. Inventories are evaluated regularly for salability, and slow moving and/or obsolete items are adjusted to expected salable value. Inventory values include direct and certain indirect costs of materials and production. Abnormal costs of production are expensed as incurred. Long Lived Assets Properties and equipment are stated at cost. Depreciation of properties and equipment is generally computed using the straight-line method over the estimated useful life of the asset. Estimated useful lives range from 20 to 30 years for buildings, 3 to 7 years for information technology equipment, 5 to 25 years for operating machinery and equipment, and 5 to 10 years for furniture and fixtures. Interest is capitalized in connection with major project expenditures. Fully depreciated assets are retained in properties and equipment and related accumulated depreciation accounts until they are removed from service. In the case of disposals, assets and related accumulated depreciation are removed from the accounts and the net amount, less any proceeds from disposal, is charged or credited to earnings. Obligations for costs associated with asset retirements, such as requirements to restore a site to its original condition, are accrued at net present value and amortized along with the related asset. Intangible assets with finite lives consist of technology, customer lists, trademarks, and other intangibles and are amortized over their estimated useful lives, ranging from 1 to 30 years. Grace reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be fully recoverable. There were no impairment charges recorded in any of the periods presented. Leases Grace leases certain real estate, office space, vehicles, railcars, and plant and office equipment, substantially all of which are accounted for as operating leases. Finance lease costs and sublease income are not material. Many of Grace’s leases contain renewal options, which are exercisable at Grace’s discretion and may be included in lease terms when they are reasonably certain to be exercised. Grace’s lease agreements do not contain material restrictive covenants or material residual value guarantees. Grace has elected not to recognize in the Consolidated Balance Sheets short-term leases, which are those with an initial term of 12 months or less. Grace has also elected not to separate lease and non-lease components. These elections apply to all asset classes. Where available, Grace uses the interest rate implicit in the lease to calculate the estimated present value of lease payment obligations. Where such a rate is not available, Grace uses an incremental borrowing rate based on credit-adjusted and term-specific discount rates, using a third-party yield curve. Goodwill Goodwill arises from business combinations, and it is reviewed for impairment on an annual basis at October 31 and whenever events or changes in circumstances indicate that the carrying amount may not be fully recoverable. Recoverability is assessed at the reporting unit level most directly associated with the business combination that generated the goodwill. For the purpose of measuring impairment, Grace has identified its operating segments as reporting units. Grace has evaluated its goodwill annually with no impairment charge required in any of the periods presented. Financial Instruments Grace uses commodity forward, swap and/or option contracts; currency forward, swap, and/or option contracts; and interest rate swap contracts to manage exposure to fluctuations in commodity prices, currency exchange rates, and interest rates. Grace does not hold or issue derivative financial instruments for trading purposes. Derivative instruments are recorded at fair value in the Consolidated Balance Sheets as either assets or liabilities. For derivative instruments designated as fair value hedges, changes in the fair values of the derivative instruments closely offset changes in the fair values of the hedged items in “other (income) expense, net” in the Consolidated Statements of Operations. For derivative instruments designated as cash flow hedges, the gain or loss on the hedge is reported in “accumulated other comprehensive income (loss)” in the Consolidated Balance Sheets until it is cleared to earnings during the same period in which the hedged item affects earnings. Forward points are excluded from the assessment of effectiveness and are amortized to income on a systematic basis. For derivative instruments designated as net investment hedges, the gains and losses on the hedge, adjusted for the impact of excluded components, are recorded net of tax to “currency translation adjustments” within “accumulated other comprehensive income (loss)” to offset the change in the carrying value of the net investment being hedged. Changes in the fair value of the hedging instrument related to time value, which are excluded from the assessment of hedge effectiveness, are recorded directly to interest expense on a systematic basis. The changes in the fair values of derivative instruments that are not designated as hedges are recorded in current period earnings. Cash flows from derivative instruments are reported in the same category as the cash flows from the items being hedged. Income Taxes Deferred tax assets and liabilities are recognized with respect to the expected future tax consequences of events that have been recorded in the Consolidated Financial Statements. Grace reduces the carrying amounts of deferred tax assets by a valuation allowance if, based on the available evidence, it is more likely than not that such assets will not be realized. The need to establish valuation allowances for deferred tax assets is assessed quarterly. In assessing the requirement for, and amount of, a valuation allowance in accordance with the more likely than not standard, Grace gives appropriate consideration to all positive and negative evidence related to the realization of the deferred tax assets. This assessment considers, among other matters, the nature, frequency, and severity of current and cumulative losses; forecasts of future profitability; domestic and foreign source income; the duration of statutory carryforward periods; and Grace’s experience with operating loss and tax credit carryforward expirations. Tax benefits from an uncertain tax position are recognized only if it is more likely than not that the tax position will be sustained upon examination by the taxing authorities based on the technical merits of the position. Tax benefits recognized in the Consolidated Financial Statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. Grace evaluates such likelihood based on relevant facts and tax law. Grace adjusts its recorded liability for income tax matters due to changes in circumstances or new uncertainties, such as amendments to existing tax law. Grace’s ultimate tax liability depends upon many factors, including negotiations with taxing authorities in the jurisdictions in which it operates, outcomes of tax litigation, and resolution of disputes arising from federal, state, and foreign tax audits. Due to the varying tax laws in each jurisdiction management, with the assistance of local tax advisors as necessary, assesses individual matters in each jurisdiction on a case-by-case basis. Grace researches and evaluates its income tax positions, including why it believes they are compliant with income tax regulations, and these positions are documented as appropriate. The U.S. Tax Cuts and Jobs Act of 2017 (“TCJA”) subjects a U.S. entity to tax on global intangible low-taxed income (“GILTI”) earned by certain foreign subsidiaries. An entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. Grace has elected to account for GILTI as a period expense in the year the tax is incurred. Grace has also adopted the tax law ordering approach for evaluating the impact of GILTI on the assessment of the realizability of US deferred tax assets. Pension Benefits Grace’s method of accounting for actuarial gains and losses relating to its global defined benefit pension plans is referred to as “mark-to-market accounting.” Under mark-to-market accounting, Grace’s pension costs consist of two elements: (1) ongoing costs recognized quarterly, which include service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits; and (2) mark-to-market gains and losses recognized annually in the fourth quarter resulting from changes in actuarial assumptions, such as discount rates and the difference between actual and expected returns on plan assets. Should a significant event occur, Grace’s pension obligation and plan assets are remeasured at an interim period, and the gains or losses on remeasurement are recognized in that period. Stock-Based Compensation The Company recognizes expenses related to stock-based compensation payment transactions in which it receives employee services in exchange for (a) equity instruments of the Company or (b) liabilities that are based on the fair value of the Company’s equity instruments or that may be settled by the issuance of equity instruments. Stock-based compensation cost for restricted stock units (“RSUs”) and share settled performance-based units (“PBUs”) are measured based on the high/low average of the Company’s common stock on the date of grant. Cash-settled RSUs are remeasured at the end of each reporting period based on the closing fair market value of the Company’s common stock. Stock-based compensation cost for stock options is estimated at the grant date based on each option’s fair value as calculated by the Black-Scholes option pricing model. The Company recognizes stock-based compensation cost as expense ratably on a straight-line basis over the requisite service period. Currency Translation Assets and liabilities of foreign subsidiaries (other than those located in countries with highly inflationary economies) are translated into U.S. dollars at current exchange rates, while revenues, costs and expenses are translated at average exchange rates during each reporting period. The resulting translation adjustments are included in “accumulated other comprehensive income (loss)” in the Consolidated Balance Sheets. The financial statements of any subsidiaries located in countries with highly inflationary economies are remeasured as if the functional currency were the U.S. dollar; the remeasurement creates translation adjustments that are reflected in net income in the Consolidated Statements of Operations. Reclassifications Certain amounts in prior years’ Consolidated Financial Statements have been reclassified to conform to the current year presentation. Such reclassifications have not materially affected previously reported amounts in the Consolidated Financial Statements. Recently Issued Accounting Standards In December 2019, the FASB issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This update clarifies and amends existing guidance, including removing certain exceptions to the general principles in Topic 740 and improves consistent application of and simplifies U.S. GAAP for other areas of Topic 740. Grace will adopt this update on January 1, 2021, when it becomes effective. Recently Adopted Accounting Standards In March 2020, the FASB issued ASU 2020-04 “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” This update is intended to ease the potential burden in accounting for and recognizing the effects of reference rate reform. It provides optional practical expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform, if certain criteria are met. This update became effective on March 12, 2020, and is available for use through December 31, 2022. Grace expects to utilize the practical expedients provided by this update in accounting for contract modifications and/or hedging transactions during the effective period. Grace expects the update to significantly reduce the effects of reference rate reform on the Consolidated Financial Statements. In August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20).” This update revises disclosure requirements related to defined benefit pension and other postretirement plans. Grace adopted this update in the 2020 first quarter, and it did not have a material effect on the Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13 “Financial Instruments—Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments.” This update requires companies to implement an impairment model based on expected credit losses, rather than probable incurred losses. Grace adopted this update in the 2020 first quarter, and it did not have a material effect on the Consolidated Financial Statements.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Inventories	Inventories are stated at the lower of cost or net realizable value, and cost is determined using FIFO. Inventories consisted of the following at December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Raw materials $ 57.0 $ 64.2 In process 38.2 55.7 Finished products 126.6 154.4 Other 32.0 35.6 $ 253.8 $ 309.9 During the three months ended June 30, 2020, Grace implemented changes to its Refining Technologies manufacturing operations to improve capital and operating efficiencies. This included key organizational changes and optimization of plant and manufacturing processes at Grace’s three hydroprocessing catalyst manufacturing sites. As a result of these changes, Grace recorded a pre-tax charge of $19.7 million related to a write-off of inventory now deemed obsolete based on the process changes.

Properties and Equipment

Properties and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Properties and Equipment	December 31, (In millions) 2020 2019 Land $ 26.5 $ 29.5 Buildings 476.6 438.9 Information technology and equipment 124.1 131.3 Machinery, equipment and other 1,956.0 1,754.5 Projects under construction 175.7 286.6 Properties and equipment, gross 2,758.9 2,640.8 Accumulated depreciation and amortization (1,550.1) (1,497.0) Properties and equipment, net $ 1,208.8 $ 1,143.8 Capitalized interest costs amounted to $7.0 million, $7.5 million, and $3.2 million in 2020, 2019, and 2018, respectively. Depreciation and finance lease amortization expense relating to properties and equipment was $82.9 million, $78.4 million, and $80.9 million in 2020, 2019, and 2018, respectively. The following table presents Grace’s lease right-of-use assets, net of accumulated amortization, and operating lease liabilities as of December 31, 2020 and 2019. December 31, (in millions) 2020 2019 Balance Sheet Location Operating lease right of use asset $ 35.1 $ 34.9 Other assets Operating lease liability—current 10.1 9.3 Other current liabilities Operating lease liability—noncurrent 25.8 26.2 Other liabilities The following table presents Grace’s costs and cash flow information related to operating leases for the year ended December 31, 2020. Year Ended December 31, (In millions) 2020 2019 Operating lease cost $ 13.3 $ 12.1 Short-term and variable lease cost 21.1 17.9 Total lease cost $ 34.4 $ 30.0 Cash payments related to operating leases $ 13.2 $ 12.0 Right-of-use assets obtained in exchange for new operating lease liabilities 10.8 17.0 Grace’s expense for operating leases was $13.5 million in 2018. The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. December 31, Weighted average discount rate 6.2 % Weighted average remaining lease term 7.7 The following maturity analysis presents minimum expected operating lease payments at December 31, 2020. (In millions) 2021 $ 11.8 2022 8.7 2023 5.2 2024 3.4 2025 2.2 Thereafter 15.3 Total undiscounted lease payments 46.6 Less: imputed interest 10.7 Present value of lease liabilities $ 35.9

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	The carrying amount of goodwill attributable to each reportable segment and the changes in those balances during the years ended December 31, 2020 and 2019, are as follows: (In millions) Catalysts Technologies Materials Technologies Total Grace Balance, December 31, 2018 $ 496.3 $ 44.1 $ 540.4 Goodwill acquired during the year 17.8 — 17.8 Foreign currency translation (1.0) (0.3) (1.3) Balance, December 31, 2019 513.1 43.8 556.9 Foreign currency translation 4.4 1.4 5.8 Balance, December 31, 2020 $ 517.5 $ 45.2 $ 562.7 Grace’s net book value of other intangible assets at December 31, 2020 and 2019, was $320.8 million and $342.8 million, respectively, detailed as follows: December 31, 2020 December 31, 2019 (In millions) Gross Carrying Accumulated Gross Carrying Accumulated Technology $ 231.6 $ 74.1 $ 232.5 $ 63.6 Customer lists 159.7 30.5 161.2 23.9 Trademarks 31.8 7.0 31.7 5.5 Other 15.7 6.4 16.1 5.7 Total $ 438.8 $ 118.0 $ 441.5 $ 98.7 Amortization expense related to intangible assets was $22.1 million, $21.9 million, and $19.9 million in 2020, 2019, and 2018, respectively. At December 31, 2020, estimated future annual amortization expense for intangible assets is: (In millions) 2021 $ 21.8 2022 21.7 2023 21.7 2024 21.7 2025 21.7 Thereafter 212.2 $ 320.8

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	Components of Debt December 31, (In millions) 2020 2019 2018 U.S. dollar term loan, net of unamortized debt issuance costs of $6.0 at December 31, 2020 (2019—$7.2) $ 922.6 $ 930.9 4.875% senior notes due 2027, net of unamortized debt issuance costs of $10.1 at December 31, 2020 739.9 — 5.625% senior notes due 2024, net of unamortized debt issuance costs of $1.9 at December 31, 2020 (2019—$2.4) 298.1 297.6 5.125% senior notes due 2021, net of unamortized debt issuance costs (2019—$2.7) — 697.3 Debt payable to unconsolidated affiliate 25.6 47.4 Other borrowings(1) 4.2 7.2 Total debt 1,990.4 $ 1,980.4 Less debt payable within one year 15.3 $ 23.1 Debt payable after one year $ 1,975.1 $ 1,957.3 Weighted average interest rates on total debt 3.5 % 3.8 % ___________________________________________________________________________________________________________________ (1) Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries. See Note 6 for a discussion of the fair value of Grace’s debt. The principal maturities of debt outstanding at December 31, 2020, were as follows: (In millions) 2021 $ 15.3 2022 14.2 2023 13.7 2024 311.4 2025 888.2 Thereafter 747.6 Total debt $ 1,990.4 Senior Notes due 2027 On June 26, 2020, Grace–Conn. (the “Issuer”) and certain of the Company’s existing domestic subsidiaries (together with the Company, the “Guarantors”), completed the sale of $750 million aggregate principal amount of 4.875% Notes due 2027 (the “Senior Notes due 2027”) for net proceeds of $741.6 million. The Senior Notes due 2027 were priced at 100% of par and were offered and sold pursuant to exemptions from registration under the Securities Act of 1933, as amended (the "Securities Act"). The Senior Notes due 2027 were issued pursuant to an indenture, dated as of September 16, 2014 (the “Base Indenture”), as supplemented by that certain third supplemental indenture, dated as of June 26, 2020 (the “Third Supplemental Indenture”), by and among the Issuer, the Guarantors and the trustee thereunder (the “Trustee”). The Base Indenture, together with the Third Supplemental Indenture, are referred to below as the “Indenture.” On July 13, 2020, Grace used the net proceeds, together with cash on hand, to redeem the $700.0 million Senior Notes due 2021 for $748.0 million, including $10.1 million of interest accrued through the date of redemption and a $37.9 million make-whole premium. During the three months ended September 30, 2020, Grace recognized a charge related to the debt refinancing of $39.4 million, including the make-whole premium. Interest is payable on the Senior Notes due 2027 on each June 15 and December 15, commencing December 15, 2020. Grace may redeem all or a portion of the Senior Notes due 2027 at any time prior to June 15, 2023, at a price equal to 100% of the principal amount of the Senior Notes due 2027 redeemed plus accrued and unpaid interest, if any, to but excluding the redemption date plus a make-whole premium. At any time on or after June 15, 2023, Grace may redeem the Senior Notes due 2027, in whole or in part, at the redemption prices set forth in the Third Supplemental Indenture, in each case plus accrued and unpaid interest, if any, to but excluding the redemption date. The Senior Notes due 2027 will mature on June 15, 2027. If a change of control of the Company occurs while the Senior Notes due 2027 are rated below investment grade, or is followed by a below investment grade rating, subject to certain exceptions, each holder shall have the right to require that the Issuer repurchase all or a portion of such holder’s Senior Notes due 2027 at a purchase price of 101% of the aggregate principal amount thereof, plus accrued and unpaid interest, if any, on the Senior Notes due 2027 repurchased, to but excluding, the date of repurchase. The Senior Notes due 2027 and guarantees are senior unsecured obligations of the Issuer and the Guarantors, respectively, and will rank equally with all of the existing and future unsubordinated obligations of the Issuer and the Guarantors, respectively. The Senior Notes due 2027 and the guarantees are effectively subordinated to any secured indebtedness to the extent of the value of the assets securing such indebtedness and structurally subordinated to the debt and other liabilities of the Company’s non-guarantor subsidiaries. The Senior Notes due 2027 were issued subject to covenants that limit the ability of the Company, the Issuer, and certain of the Company’s subsidiaries to: (i) incur liens on assets; (ii) enter into sale and leaseback transactions larger than the greater of $100 million or 2.5% of total assets; and (iii) merge or consolidate with another company; subject to certain exceptions and qualifications. Grace is in compliance with those covenants. The Senior Notes due 2027 were issued subject to customary events of default, which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for payment of the greater of (i) $100 million and (ii) 2.5% of Total Assets (as defined in the Indenture) or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the Trustee or the holders of at least 30% in aggregate principal amount of the then outstanding series of Senior Notes due 2027 may declare all the Senior Notes due 2027 of such series to be due and payable immediately. The foregoing is a summary of the Senior Notes due 2027 and the related indentures, does not purport to be complete, and is qualified in its entirety by reference to the full texts thereof. Grace has filed the full text of such documents with the SEC, which are readily available on the internet at www.sec.gov. Credit Agreement On April 3, 2018, Grace entered into a Credit Agreement (the “Credit Agreement”), which provides for new senior secured credit facilities, consisting of: (a) a $950 million term loan due in 2025, with interest at LIBOR +175 basis points, and (b) a $400 million revolving credit facility due in 2023, with interest at LIBOR +175 basis points. The term loan amortizes in equal quarterly installments in aggregate annual amounts of $9.5 million. The Credit Agreement contains customary affirmative covenants, including, but not limited to: (i) maintenance of existence, and compliance with laws; (ii) delivery of consolidated financial statements and other information; (iii) payment of taxes; (iv) delivery of notices of defaults and certain other material events; and (v) maintenance of adequate insurance. The Credit Agreement also contains customary negative covenants, including but not limited to restrictions on: (i) dividends on, and redemptions of, equity interests and other restricted payments; (ii) liens; (iii) loans and investments; (iv) the sale, transfer or disposition of assets and businesses; (v) transactions with affiliates; and (vi) a maximum first lien leverage ratio. Events of default under the Credit Agreement include, but are not limited to: (i) failure to pay principal, interest, fees or other amounts under the Credit Agreement when due, taking into account any applicable grace period; (ii) any representation or warranty proving to have been incorrect in any material respect when made; (iii) failure to perform or observe covenants or other terms of the Credit Agreement subject to certain grace periods; (iv) a cross-default and cross-acceleration with certain other material debt; (v) bankruptcy events; (vi) certain defaults under ERISA; and (vii) the invalidity or impairment of security interests. To secure its obligations under the Credit Agreement, Grace and certain of its U.S. subsidiaries have granted security interests in substantially all equity and debt interests in Grace–Conn. or any other Grace subsidiary owned by them and in substantially all their non-real estate assets and property. Grace used a portion of the proceeds to repay in full the borrowings outstanding under its 2014 credit agreement, which was terminated, as well as to make a voluntary $50.0 million accelerated contribution to its U.S. qualified pension plans. In connection with the repayment of debt, Grace recorded a $4.8 million loss on early extinguishment of debt, which is included in “other (income) expense” in the Consolidated Statement of Operations. Grace had no outstanding draws on its revolving credit facility as of December 31, 2020; however, the available credit under the facility was reduced to $391.8 million by outstanding letters of credit. Senior Notes due 2021 and 2024 On September 16, 2014, Grace–Conn. (the “Issuer”) issued $1,000.0 million of senior unsecured notes (the “Notes”) in two tranches: (a) $700 million in aggregate principal amount of Notes due 2021 at a coupon rate of 5.125%, and (b) $300 million in aggregate principal amount of Notes due 2024 at a coupon rate of 5.625%. The Notes were priced at 100% of par and were offered and sold pursuant to exemptions from registration under the Securities Act of 1933, as amended, (the “Securities Act”). Interest is payable on the Notes on each April 1 and October 1. Grace may redeem some or all of the Notes at any time at a price equal to the greater of (i) 100% of the principal amount of the Notes redeemed plus accrued and unpaid interest and (ii) the sum, as determined by an independent investment banker, of the present values of the remaining scheduled payments of principal and interest (exclusive of interest accrued to the date of redemption) discounted to the redemption date on a semiannual basis (assuming a 360-day year consisting of twelve 30-day months) at the treasury rate plus 50 basis points, in each case, plus accrued and unpaid interest. In the event of a change in control, Grace will be required to offer to purchase the Notes at a price equal to 101% of the aggregate principal amount outstanding plus accrued and unpaid interest. On July 13, 2020, Grace redeemed the $700.0 million Senior Notes due 2021. The Notes are jointly and severally guaranteed on a full and unconditional senior unsecured basis by the Company and Alltech Associates, Inc., a wholly-owned subsidiary of the Issuer (the “Guarantors”). The Notes and guarantees are senior obligations of the Issuer and the Guarantors, respectively, and will rank equally with all of the existing and future unsubordinated obligations of the Issuer and the Guarantors, respectively. The Notes are effectively subordinated to any secured indebtedness to the extent of the value of the assets securing such indebtedness, and structurally subordinated to the debt and other liabilities of Grace’s non-guarantor subsidiaries. The Notes were issued subject to covenants that limit the Issuer’s and certain of its subsidiaries’ ability, subject to certain exceptions and qualifications, to (i) create or incur liens on assets, (ii) enter into any sale and leaseback transaction and (iii) in the case of the Issuer, merge or consolidate with another company. Grace is in compliance with these covenants. The Notes were also issued subject to customary events of default which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for the payment of $75 million or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the trustee or the holders of at least 25% in aggregate principal amount of the then outstanding series of Notes may declare all the Notes of such series to be due and payable immediately. The foregoing is a summary of the Credit Agreement, the indentures, and the Notes. Grace has filed the full text of such agreements with the SEC, which are readily available on the Internet at www.sec.gov.

Fair Value Measurements and Ris

Fair Value Measurements and Risk	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements and Risk	Certain of Grace’s assets and liabilities are reported at fair value on a gross basis. ASC 820 “Fair Value Measurements and Disclosures” defines fair value as the value that would be received at the measurement date in the principal or “most advantageous” market. Grace uses principal market data, whenever available, to value assets and liabilities that are required to be reported at fair value. Grace has identified the following financial assets and liabilities that are subject to the fair value analysis required by ASC 820: Fair Value of Debt and Other Financial Instruments Debt payable is recorded at carrying value. Fair value is determined based on Level 2 inputs, including expected future cash flows (discounted at market interest rates), estimated current market prices, and quotes from financial institutions. At December 31, 2020, the carrying amounts, net of unamortized debt issuance costs and discounts (see Note 5), and fair values of Grace’s debt were as follows: December 31, 2020 December 31, 2019 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 2018 U.S. dollar term loan $ 922.6 $ 904.1 $ 930.9 $ 938.1 4.875% senior notes due 2027 739.9 784.7 — — 5.625% senior notes due 2024 298.1 322.4 297.6 329.2 5.125% senior notes due 2021 — — 697.3 727.1 Other borrowings 29.8 29.8 54.6 54.6 Total debt $ 1,990.4 $ 2,041.0 $ 1,980.4 $ 2,049.0 At December 31, 2020, the recorded values of other financial instruments such as cash equivalents and trade receivables and payables approximated their fair values, based on the short-term maturities and floating rate characteristics of these instruments. Currency Derivatives Because Grace operates and/or sells to customers in over 60 countries and in over 30 currencies, its results are exposed to fluctuations in currency exchange rates. Grace seeks to minimize exposure to these fluctuations by matching sales with expenditures in the same currencies, but it is not always possible to do so. From time to time, Grace uses financial instruments such as currency forward contracts, options, swaps, or combinations thereof to reduce the risk of certain specific transactions. However, Grace does not have a policy of hedging all exposures, because management does not believe that such a level of hedging would be cost-effective. Forward contracts with maturities of not more than 36 months are used and designated as cash flow hedges of forecasted repayments of intercompany loans. The effective portion of gains and losses on these currency hedges is recorded in “accumulated other comprehensive income (loss)” and reclassified into “other (income) expense, net” to offset the remeasurement of the underlying hedged loans. Forward points are excluded from the assessment of effectiveness and amortized to income on a systematic basis. Grace also enters into foreign currency forward contracts and swaps to hedge a portion of its net outstanding monetary assets and liabilities. These forward contracts and swaps are not designated as hedging instruments under applicable accounting guidance, and therefore all changes in their fair value are recorded in “other (income) expense, net,” in the Consolidated Statements of Operations. These forward contracts and swaps are intended to offset the foreign currency gains or losses associated with the underlying monetary assets and liabilities. The valuation of Grace’s currency exchange rate forward contracts and swaps is determined using an income approach. Inputs used to value currency exchange rate forward contracts and swaps consist of: (1) spot rates, which are quoted by various financial institutions; (2) forward points, which are primarily affected by changes in interest rates; and (3) discount rates used to present value future cash flows, which are based on the London Interbank Offered Rate (LIBOR) curve or overnight indexed swap rates. Total notional amounts for forward contracts and swaps outstanding at December 31, 2020, were $419.2 million. Cross-Currency Swap Agreements Grace uses cross-currency swaps designated as cash flow hedges to manage fluctuations in currency exchange rates and interest rates on variable rate debt. Gains and losses on these cash flow hedges are recorded in “accumulated other comprehensive income (loss)” and reclassified into “other (income) expense, net” and “interest expense and related financing costs” during the hedged period. In connection with the Credit Agreement (see Note 5), Grace entered into new cross-currency swaps beginning on April 3, 2018, and maturing on March 31, 2023, to synthetically convert $600.0 million of U.S. dollar-denominated floating rate debt into €490.1 million of euro-denominated debt fixed at 2.0231%. These cross-currency swaps were de-designated and terminated on November 5, 2018, and replaced with new, at-market cross-currency swaps beginning on November 5, 2018, and maturing on March 31, 2023, to synthetically convert $600.0 million of U.S. dollar-denominated floating rate debt into €525.9 million of euro-denominated debt fixed at 1.785%. Grace received $33.1 million in cash proceeds from the swap settlement. The valuation of these cross-currency swaps is determined using an income approach, using LIBOR and EURIBOR (Euro Interbank Offered Rate) swap curves, currency basis spreads, and euro/U.S. dollar exchange rates. Debt and Interest Rate Swap Agreements Grace uses interest rate swaps designated as cash flow hedges to manage fluctuations in interest rates on variable rate debt. The effective portion of gains and losses on these interest rate cash flow hedges is recorded in “accumulated other comprehensive income (loss)” and reclassified into “interest expense and related financing costs” during the hedged interest period. In connection with the Credit Agreement, Grace entered into interest rate swaps beginning on April 3, 2018, and maturing on March 31, 2023, fixing the LIBOR component of the interest on $100.0 million of term debt at 2.775%. The valuation of these interest rate swaps is determined using an income approach, using prevailing market interest rates and discount rates to present value future cash flows based on the forward LIBOR yield curves. Credit risk is also incorporated into derivative valuations. The following tables present the fair value hierarchy for financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019: Fair Value Measurements at December 31, 2020, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Assets Currency derivatives $ 1.6 $ — $ 1.6 $ — Total Assets $ 1.6 $ — $ 1.6 $ — Liabilities Currency derivatives $ 17.8 $ — $ 17.8 $ — Variable-to-fixed cross-currency derivatives 51.0 — 51.0 — Interest rate derivatives 5.5 — 5.5 — Total Liabilities $ 74.3 $ — $ 74.3 $ — Fair Value Measurements at December 31, 2019, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Assets Currency derivatives $ 6.1 $ — $ 6.1 $ — Variable-to-fixed cross-currency derivatives 3.4 — 3.4 — Total Assets $ 9.5 $ — $ 9.5 $ — Liabilities Currency derivatives $ 0.9 $ — $ 0.9 $ — Interest rate derivatives 3.4 — 3.4 — Total Liabilities $ 4.3 $ — $ 4.3 $ — The following tables present the location and fair values of derivative instruments included in the Consolidated Balance Sheets as of December 31, 2020 and 2019: Asset Derivatives Liability Derivatives December 31, 2020 Balance Sheet Fair Balance Sheet Fair Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ — Other current liabilities $ 17.7 Currency contracts Other assets — Other liabilities 0.1 Interest rate contracts Other current assets — Other current liabilities 2.5 Interest rate contracts Other assets — Other liabilities 3.0 Variable-to-fixed cross-currency swaps Other current assets — Other current liabilities 0.2 Variable-to-fixed cross-currency swaps Other liabilities — Other liabilities 50.8 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 1.9 Other current assets — Currency contracts Other current liabilities (0.3) Other current liabilities — Total derivatives $ 1.6 $ 74.3 Asset Derivatives Liability Derivatives December 31, 2019 Balance Sheet Fair Balance Sheet Fair Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.1 Other current assets $ (3.1) Currency contracts Other assets 4.0 Other liabilities 4.0 Interest rate contracts Other current assets — Other current liabilities 1.0 Interest rate contracts Other assets — Other liabilities 2.4 Variable-to-fixed cross-currency swaps Other current assets 10.2 Other current liabilities — Variable-to-fixed cross-currency swaps Other liabilities (6.8) Other liabilities — Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets — Other current assets (0.2) Currency contracts Other current assets — Other current liabilities 0.2 Total derivatives $ 9.5 $ 4.3 The following tables present the location and amount of gains and losses on derivative instruments included in the Consolidated Statements of Operations or, when applicable, gains and losses initially recognized in “other comprehensive income (loss)” (“OCI”) for the years ended December 31, 2020, 2019, and 2018: Year Ended December 31, 2020 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (4.0) Interest expense $ (1.8) Currency contracts(1) 1.8 Other expense 2.3 Variable-to-fixed cross-currency swaps 7.2 Interest expense 4.0 Variable-to-fixed cross-currency swaps (55.4) Other expense (55.4) Total derivatives $ (50.4) $ (50.9) Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ 4.9 ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.7) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Year Ended December 31, 2019 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (2.9) Interest expense $ (0.3) Currency contracts(1) 2.4 Other expense 1.4 Variable-to-fixed cross-currency swaps 9.1 Interest expense 13.2 Variable-to-fixed cross-currency swaps 12.5 Other expense 12.5 Total derivatives $ 21.1 $ 26.8 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (0.4) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $0.6 million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Year Ended December 31, 2018 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 0.4 Interest expense $ (0.6) Currency contracts(1) 6.3 Other expense 6.3 Variable-to-fixed cross-currency swaps (0.6) Interest expense 9.7 Variable-to-fixed cross-currency swaps 40.5 Other expense 40.5 Total derivatives $ 46.6 $ 55.9 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (4.0) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.4) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. The following table presents the total amounts of income and expense line items presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are reported. Year Ended December 31, 2020 2019 2018 (In millions) Interest expense Other income (expense) Interest expense Other income (expense) Interest expense Other income (expense) Total amounts of income and expense line items in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded $ (76.0) $ (89.0) $ (76.7) $ (80.6) $ (80.2) $ 23.2 Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Gain (loss) reclassified from accumulated OCI into income $ (1.8) $ — $ (0.3) $ — $ (0.6) $ — Variable-to-fixed cross-currency swaps Gain (loss) reclassified from accumulated OCI into income 4.0 (55.4) 13.2 12.5 9.7 40.5 Currency contracts Gain (loss) reclassified from accumulated OCI into income — 2.3 — 1.4 — 6.3 Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 1.2 — 2.8 — 3.0 Net Investment Hedges Grace uses cross-currency swaps as derivative hedging instruments in certain net investment hedges of its non-U.S. subsidiaries. The gains and losses attributable to these net investment hedges, adjusted for the impact of excluded components, are recorded net of tax to “currency translation adjustments” within “accumulated other comprehensive income (loss)” to offset the change in the carrying value of the net investment being hedged. Recognition in earnings of amounts previously recorded to “currency translation adjustments” is limited to circumstances such as complete or substantially complete liquidation of the net investment in the hedged foreign operation. Changes in the fair value of the hedging instrument related to time value, which are excluded from the assessment of hedge effectiveness, are recorded directly to interest expense on a systematic basis. These gains were $3.0 million, $3.3 million and $2.3 million for the years ended December 31, 2020, 2019, and 2018, respectively. At December 31, 2020, the notional amount of €170.0 million of Grace’s cross-currency swaps was designated as a hedging instrument of its net investment in its European subsidiaries. Grace has also used foreign currency-denominated debt and deferred intercompany royalties as non-derivative hedging instruments in certain net investment hedges. At December 31, 2020, Grace’s deferred intercompany royalties have been fully amortized and de-designated as a hedging instrument of its net investment in its European subsidiaries. In April 2018, in connection with the Credit Agreement, Grace de-designated and repaid its euro-denominated term loan principal that had been designated as a hedge of its net investment in its European subsidiaries. The following table presents the amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges recorded to “currency translation adjustments” within “accumulated other comprehensive income (loss)” for the years ended December 31, 2020, 2019, and 2018. There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented. Year Ended December 31, (In millions) 2020 2019 2018 Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ (15.9) $ 9.1 $ 6.0 Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ — $ — $ (4.4) Foreign currency denominated deferred intercompany royalties — 0.1 0.5 $ — $ 0.1 $ (3.9) Credit Risk Grace is exposed to credit risk in its trade accounts receivable. Grace’s credit evaluation policies mitigate credit risk exposures, and it has a history of minimal credit losses. Grace does not generally require collateral for its trade accounts receivable, but may require a bank letter of credit in certain instances, particularly when selling to customers in cash-restricted countries. Grace may also be exposed to credit risk in its derivatives contracts. Grace monitors counterparty credit risk and currently does not anticipate nonperformance by counterparties to its derivatives. Grace’s derivative contracts are with internationally recognized commercial financial institutions.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Provision for Income Taxes The components of income from continuing operations before income taxes and the related provision for income taxes for 2020, 2019, and 2018 are as follows: (In millions) 2020 2019 2018 Income from continuing operations before income taxes: Domestic $ (76.1) $ 79.2 $ 82.2 Foreign 76.6 104.3 162.7 Total $ 0.5 $ 183.5 $ 244.9 Benefit from (provision for) income taxes: Federal—current $ (0.3) $ (6.3) $ (4.9) Federal—deferred 24.8 (19.8) (29.3) State and local—current — (0.5) 1.6 State and local—deferred (7.2) (5.8) (3.5) Foreign—current (35.1) (42.4) (49.9) Foreign—deferred 15.6 18.0 7.9 Total $ (2.2) $ (56.8) $ (78.1) The difference between the benefit from (provision for) income taxes on continuing operations at the U.S. federal income tax rate of 21% and Grace’s overall income tax provision is summarized as follows: (In millions) 2020 2019 2018 Tax provision at U.S. federal income tax rate $ (0.1) $ (38.5) $ (51.4) Change in benefit (provision) resulting from: GILTI high-tax exclusion amended return 25.2 — — Decrease (increase) in valuation allowance (13.5) (4.2) (6.3) Nontaxable income/non-deductible expenses (4.6) (2.5) (1.6) U.S. taxes on foreign earnings (3.9) (16.7) (30.9) State and local income taxes, net (3.4) (3.4) (1.9) Research and development credit 3.3 3.4 9.4 Unrecognized tax benefit (accruals) releases (3.1) 2.3 5.7 Effect of tax rate differential in foreign jurisdictions (2.0) (2.9) (11.3) Compensation-related adjustments (1.8) (1.7) (3.4) Provision to return adjustments (0.3) 3.0 (0.7) Benefits (charges) related to U.S. tax reform — — 17.1 Other 2.0 4.4 (2.8) Benefit from (provision for) income taxes $ (2.2) $ (56.8) $ (78.1) Our 2020 effective tax rate was significantly higher than the 21% U.S. statutory rate primarily due to proportionally lower pre-tax income and to an increase to the valuation allowance on U.S. federal tax credits and the higher statutory rates in effect for our foreign subsidiaries, partially offset by the benefit from the Global Intangible Low-Taxed Income (“GILTI”) high-tax exclusion (“HTE”) tax benefit elected for tax years 2018 through 2020. On July 20, 2020, the U.S. Treasury Department released final regulations related to the GILTI HTE. Grace has recognized a benefit associated with the GILTI HTE regulations that resulted in a tax benefit related to 2018 and 2019 of $25.2 million resulting from the election and the re-establishment of certain U.S. federal net operating loss carryforwards, research and development credit carryforwards, and foreign tax credit carryforwards. Deferred Tax Assets and Liabilities As of December 31, 2020 and 2019, the tax attributes giving rise to deferred tax assets and liabilities consisted of the following items. December 31, (In millions) 2020 2019 Deferred tax assets: Tax credit carryforwards $ 309.2 $ 294.7 Pension liabilities 139.2 107.7 Net operating loss carryforwards 65.2 60.3 Environmental remediation liabilities 50.3 47.0 Research and development 32.9 26.6 Unrealized currency gains and losses 30.7 12.1 Reserves and allowances 29.6 14.8 Operating lease liabilities 7.4 8.1 Compensation-related 4.0 5.4 Prepaid royalties 1.1 6.3 Other 6.8 6.9 Total deferred tax assets $ 676.4 $ 589.9 Deferred tax liabilities: Intangible assets $ (36.5) $ (27.7) Properties and equipment (20.5) (18.6) Operating lease assets (7.4) (8.0) Other (16.6) (1.4) Total deferred tax liabilities $ (81.0) $ (55.7) Valuation allowances (38.7) (24.1) Net deferred tax assets $ 556.7 $ 510.1 Grace reduces the carrying amounts of deferred tax assets by a valuation allowance if, based on the available evidence, it is more likely than not that such assets will not be realized (see Note 1). Based on all available evidence considered, Grace believes it is more likely than not that some portion of the U.S federal foreign tax credit carryforwards recorded will not ultimately be realized. As of December 31, 2020, a valuation allowance of $11.5 million was recorded against the more-likely-than-not U.S. federal foreign tax credit carryforwards expiring in 2021. Tax Attributes—Tax Credit and Net Operating Loss Carryforwards Grace has $317.4 million in federal tax credit carryforwards and $13.1 million in federal net operating loss carryforwards before valuation allowances and unrecognized tax benefits. In order to fully utilize the credits before they expire (from 2021 to 2040), Grace would need to generate income of approximately $1.6 billion. Grace has state net operating loss carryforwards of $47.4 million and state tax credits of $1.6 million before valuation allowances and unrecognized tax benefits. In order to fully utilize the state tax attributes before they expire (from 2021 to 2036), Grace would need to generate approximately $3.1 billion in state taxable income. The following table presents Grace’s tax effected net operating loss carryforwards and the related valuation allowances. December 31, (In millions) 2020 2019 Net operating loss carryforwards U.S. state net operating losses $ 45.4 $ 49.5 U.S. federal net operating losses 10.2 1.2 Foreign net operating losses 9.6 9.6 Net operating loss carryforwards $ 65.2 $ 60.3 Net operating loss—valuation allowances U.S. state—NOL valuation allowances $ (13.9) $ (10.1) Foreign—NOL valuation allowances (6.5) (8.0) Net operating loss—valuation allowances $ (20.4) $ (18.1) Unrecognized Tax Benefits The balance of unrecognized tax benefits at December 31, 2020, was $18.6 million compared with $15.4 million at December 31, 2019. A rollforward of the balance of unrecognized tax benefits for the three years ended December 31, 2020, follows. December 31, (In millions) 2020 2019 2018 Balance at beginning of year $ 15.4 $ 14.1 $ 17.7 Increase (decrease) in positions taken in prior periods 0.2 2.6 1.2 Positions taken in the current period 3.4 2.9 0.9 Decrease due to settlements with tax authorities (0.4) (4.2) (5.7) Balance at end of year $ 18.6 $ 15.4 $ 14.1 If the balance of unrecognized tax benefits as of December 31, 2020, of $18.6 million is ultimately recognized, it would reduce the effective tax rate. A portion of this balance relates to tax positions that impact Grace’s deferred tax assets as of December 31, 2020. Grace accrues potential interest and any associated penalties related to unrecognized tax benefits in “benefit from (provision for) income taxes” in the Consolidated Statements of Operations. Grace accrued $0.2 million of interest and penalties associated with these unrecognized tax benefits in 2020. Grace believes that the amount of the liability for unrecognized tax benefits will not change materially in the next 12 months. Grace is subject to taxation in the U.S. and various state and foreign jurisdictions and is under continual audit by various tax authorities. As of December 31, 2020, tax years 2017 through 2019 are subject to examination by the U.S. tax authorities. In the significant non-U.S. jurisdiction, tax years 2017 through 2019 are subject to examination by the German tax authorities. Grace has tax attributes generated in prior years that are otherwise closed by statute and were carried forward into years that are open to examination. Those attributes may still be subject to adjustment to the extent utilized in open years.

Pension Plans and Other Retirem

Pension Plans and Other Retirement Plans	12 Months Ended
	Dec. 31, 2020
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension Plans and Other Postretirement Benefit Plans	Pension Plans The following table presents the funded status of Grace’s pension plans: December 31, (In millions) 2020 2019 Overfunded defined benefit pension plans $ 11.4 $ 8.5 Underfunded defined benefit pension plans (128.3) (85.2) Unfunded defined benefit pension plans (520.7) (434.6) Total underfunded and unfunded defined benefit pension plans (649.0) (519.8) Pension liabilities included in other current liabilities (15.7) (14.8) Net funded status $ (653.3) $ (526.1) Fully-funded plans include several advance-funded plans where the fair value of the plan assets exceeds the projected benefit obligation ("PBO"). Underfunded plans include a group of advance-funded plans that are underfunded on a PBO basis. Unfunded plans include several plans that are funded on a pay-as-you-go basis, and therefore, the entire PBO is unfunded. Grace maintains defined benefit pension plans covering current and former employees of certain business units and divested business units who meet age and service requirements. Benefits are generally based on final average salary and years of service. Grace funds its U.S. qualified pension plans (“U.S. qualified pension plans”) in accordance with U.S. federal laws and regulations. Non-U.S. pension plans (“non-U.S. pension plans”) are funded under a variety of methods, as required under local laws and customs. The U.S. salaried plan was closed to new entrants after January 1, 2017. In the 2021 first quarter, Grace announced to employees that the U.S. salaried plan will be frozen effective January 1, 2025. Grace also provides, through nonqualified plans, supplemental pension benefits in excess of U.S. qualified pension plan limits imposed by federal tax law. These plans cover officers and higher-level employees and serve to increase the combined pension amount to the level that they otherwise would have received under the U.S. qualified pension plans in the absence of such limits. The nonqualified plans are unfunded and Grace pays the costs of benefits as they are due to the participants. At the December 31, 2020, measurement date for Grace’s defined benefit pension plans, the PBO was $1,682.7 million as measured under U.S. GAAP compared with $1,507.0 million as of December 31, 2019. The PBO reflects the present value (using a 2.41% weighted average discount rate for U.S. plans and a 0.84% weighted average discount rate for non-U.S. plans as of December 31, 2020) of vested and non-vested benefits earned from employee service to date, based upon current services and estimated future pay increases for active employees. On an annual basis a full remeasurement of pension assets and pension liabilities is performed based on Grace’s estimates and actuarial valuations. These valuations reflect the terms of each pension plan and use participant-specific information as well as certain key assumptions provided by management. Defined Contribution Retirement Plans Grace sponsors a defined contribution retirement plan for its employees in the United States. This plan is qualified under section 401(k) of the U.S. tax code. Currently, Grace contributes an amount equal to 100% of employee contributions, up to 6% of an individual employee’s salary or wages. Grace’s cost related to this benefit plan was $14.3 million, $13.9 million, and $12.6 million for the years ended December 31, 2020, 2019, and 2018, respectively. U.S. salaried employees and certain U.S. hourly employees hired on or after January 1, 2017, participate in an enhanced defined contribution plan instead of a defined benefit pension plan. Grace contributes 4% of an individual employee’s salary or wages to this plan. Grace’s cost related to this enhanced defined contribution plan established in the U.S. was $3.5 million, $2.9 million, and $1.7 million for the years ended December 31, 2020, 2019, and 2018, respectively. Analysis of Plan Accounting and Funded Status The following table summarizes the changes in benefit obligations and fair values of retirement plan assets during 2020 and 2019: Defined Benefit Pension Plans U.S. Non-U.S. Total (In millions) 2020 2019 2020 2019 2020 2019 Change in Projected Benefit Obligation: Benefit obligation at beginning of year $ 1,137.8 $ 1,027.1 $ 369.2 $ 305.6 $ 1,507.0 $ 1,332.7 Service cost 18.9 15.7 11.1 8.6 30.0 24.3 Interest cost 30.2 38.3 4.1 5.4 34.3 43.7 Actuarial (gain) loss—change in discount rates 106.0 144.1 52.7 58.2 158.7 202.3 Actuarial (gain) loss—other changes 8.9 (10.7) (3.7) 4.1 5.2 (6.6) Benefits paid (79.1) (76.7) (8.4) (8.4) (87.5) (85.1) Currency exchange translation adjustments — — 35.0 (4.3) 35.0 (4.3) Benefit obligation at end of year $ 1,222.7 $ 1,137.8 $ 460.0 $ 369.2 $ 1,682.7 $ 1,507.0 Change in Plan Assets: Fair value of plan assets at beginning of year $ 955.7 $ 871.1 $ 25.2 $ 19.5 $ 980.9 $ 890.6 Actual return on plan assets 115.7 154.6 2.3 4.1 118.0 158.7 Employer contributions 8.4 6.7 8.8 9.1 17.2 15.8 Benefits paid (79.1) (76.7) (8.4) (8.4) (87.5) (85.1) Currency exchange translation adjustments — — 0.8 0.9 0.8 0.9 Fair value of plan assets at end of year $ 1,000.7 $ 955.7 $ 28.7 $ 25.2 $ 1,029.4 $ 980.9 Funded status at end of year (PBO basis) $ (222.0) $ (182.1) $ (431.3) $ (344.0) $ (653.3) $ (526.1) Amounts recognized in the Consolidated Balance Sheets consist of: Noncurrent assets $ 11.4 $ 8.5 $ — $ — $ 11.4 $ 8.5 Current liabilities (7.2) (7.3) (8.5) (7.5) (15.7) (14.8) Noncurrent liabilities (226.2) (183.3) (422.8) (336.5) (649.0) (519.8) Net amount recognized $ (222.0) $ (182.1) $ (431.3) $ (344.0) $ (653.3) $ (526.1) Amounts recognized in Accumulated Other Comprehensive (Income) Loss consist of: Prior service credit $ (2.0) $ (2.6) $ (0.1) $ (0.1) $ (2.1) $ (2.7) Net amount recognized $ (2.0) $ (2.6) $ (0.1) $ (0.1) $ (2.1) $ (2.7) Defined Benefit Pension Plans U.S. Non-U.S. 2020 2019 2020 2019 Weighted Average Assumptions Used to Determine Benefit Obligations as of December 31: Discount rate 2.41 % 3.13 % 0.84 % 1.41 % Rate of compensation increase 4.50 % 4.50 % 2.58 % 2.59 % Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended December 31: Discount rate for determining service cost 3.40 % 4.46 % 1.61 % 2.42 % Discount rate for determining interest cost 2.75 % 3.86 % 1.12 % 1.84 % Expected return on plan assets 5.25 % 5.75 % 4.17 % 4.43 % Rate of compensation increase 4.50 % 4.10 % 2.59 % 2.59 % The following table presents the components of net periodic benefit cost (income) and other amounts recognized in “other comprehensive (income) loss.” (In millions) 2020 2019 2018 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Net Periodic Benefit Cost (Income) Service cost $ 18.9 $ 11.1 $ 15.7 $ 8.6 $ 19.2 $ 9.5 Interest cost 30.2 4.1 38.3 5.4 40.9 5.0 Expected return on plan assets (48.3) (1.0) (48.2) (0.9) (57.2) (1.0) Amortization of prior service cost (credit) (0.6) — (0.6) — (0.6) — Annual mark-to-market adjustment (gain) loss 47.5 47.1 26.8 59.1 (3.4) (9.2) Net curtailment and settlement gain — — — — (2.3) — Net periodic benefit cost (income) $ 47.7 $ 61.3 $ 32.0 $ 72.2 $ (3.4) $ 4.3 Other Changes in Plan Assets and Benefit Obligations Recognized in OCI Amortization of prior service cost (credit) $ 0.6 $ — $ 0.6 $ — $ 0.6 $ — Total recognized in OCI 0.6 — 0.6 — 0.6 — Total recognized in net periodic benefit cost (income) and OCI $ 48.3 $ 61.3 $ 32.6 $ 72.2 $ (2.8) $ 4.3 During 2020 the pension plans experienced a loss on liability mainly due to the decrease in discount rates from the prior year. A change in the mortality assumption for the U.S. pension plans to better reflect anticipated future experience also contributed to the loss. The loss was partially offset due to return on assets greater than expected and salary increases during the year less than expected. The tables below present the funded status of U.S. and non-U.S. pension plans. Funded Status of U.S. Pension Plans Fully-Funded U.S. Qualified Underfunded U.S. Unfunded Pay-As-You-Go (In millions) 2020 2019 2020 2019 2020 2019 Projected benefit obligation $ 36.5 $ 35.6 $ 1,076.3 $ 993.8 $ 109.9 $ 108.3 Fair value of plan assets 47.9 44.1 952.8 911.5 — — Funded status (PBO basis) $ 11.4 $ 8.5 $ (123.5) $ (82.3) $ (109.9) $ (108.3) Funded Status of Non-U.S. Pension Plans Underfunded Non-U.S. Unfunded Pay-As-You-Go (In millions) 2020 2019 2020 2019 Projected benefit obligation $ 33.5 $ 29.0 $ 426.5 $ 340.2 Fair value of plan assets 28.7 25.2 — — Funded status (PBO basis) $ (4.8) $ (3.8) $ (426.5) $ (340.2) ___________________________________________________________________________________________________________________ (1) Plans intended to be advance-funded. (2) Plans intended to be pay-as-you-go. The U.S. unfunded plans are Grace’s supplemental executive retirement plan and other supplemental executive pension arrangements, and the non-U.S. plans primarily relate to an unfunded German pension plan. The accumulated benefit obligation for all defined benefit pension plans was approximately $1,590 million and $1,423 million as of December 31, 2020 and 2019, respectively. The following table presents the funded status of defined benefit pension plans that are underfunded or unfunded on an accumulated benefit obligation basis. U.S. Non-U.S. Total 2020 2019 2020 2019 2020 2019 Projected benefit obligation $ 1,186.2 $ 1,102.1 $ 429.4 $ 342.1 $ 1,615.6 $ 1,444.2 Accumulated benefit obligation 1,144.2 1,058.6 384.0 306.7 1,528.2 1,365.3 Fair value of plan assets 952.8 911.6 1.3 0.8 954.1 912.4 Estimated Expected Future Benefit Payments Including Future Service for the Fiscal Years Ending Pension Plans Total U.S. Non-U.S.(1) Benefit Benefit 2021 $ 84.5 $ 9.7 $ 94.2 2022 77.5 9.4 86.9 2023 76.4 9.6 86.0 2024 76.0 10.1 86.1 2025 74.2 10.2 84.4 2026 - 2030 348.6 60.5 409.1 ___________________________________________________________________________________________________________________ (1) Non-U.S. estimated benefit payments for 2021 and future periods have been translated at the applicable December 31, 2020, exchange rates. Discount Rate Assumption The assumed discount rate for pension plans reflects the market rates for high-quality corporate bonds currently available and is subject to change based on changes in overall market interest rates. For the U.S. qualified pension plans, the assumed weighted average discount rate of 2.41% as of December 31, 2020, was selected by Grace, in consultation with its independent actuaries, based on a yield curve constructed from a portfolio of high quality bonds for which the timing and amount of cash outflows approximate the estimated payouts of the plan. As of December 31, 2020 and 2019, the German pension plans represented approximately 92% and 91%, respectively, of the benefit obligation of the non-U.S. pension plans. The assumed weighted average discount rate as of December 31, 2020, for Germany of 0.70% was selected by Grace, in consultation with its independent actuaries, based on a yield curve constructed from a portfolio of euro-denominated high quality bonds for which the timing and amount of cash outflows approximate the estimated payouts of the plans. The assumed discount rates for the remaining non-U.S. pension plans were determined based on the nature of the liabilities, local economic environments and available bond indices. Investment Guidelines for Advance-Funded Pension Plans The investment goal for the U.S. qualified pension plans subject to advance funding is to earn a long-term rate of return consistent with the related cash flow profile of the underlying benefit obligation. The plans are pursuing a well-defined risk management strategy designed to reduce investment risks as their funded status improves. The U.S. qualified pension plans have adopted a diversified set of portfolio management strategies to optimize the risk reward profile of the plans: • Liability hedging portfolio: primarily invested in intermediate-term and long-term investment grade corporate bonds in actively managed strategies. • Return-seeking portfolio: invested in a diversified set of assets designed to deliver performance in excess of the underlying liabilities with controls regarding the level of risk. ◦ Global public equities: the portfolio contains both domestic U.S. and non-U.S. equities that are both passively and actively managed. Benchmarks for individual managers include S&P 500 and Russell 2000 benchmarks as well as MSCI ACWI ex US index. ◦ Other investments: may include high yield bonds: fixed income portfolio of securities below investment grade including non-U.S. issuers. These portfolios combine income generation and capital appreciation opportunities globally. • Liquidity portfolio: invested in short-term assets intended to pay periodic plan benefits and expenses. For 2020, the expected long-term rate of return on assets for the U.S. qualified pension plans was 5.25%. Average annual returns over one-, three-, five-, and ten-year periods were approximately 13%, 9%, 10%, and 8%, respectively. The expected return on plan assets for the U.S. qualified pension plans for 2020 was selected by Grace, in consultation with its independent actuaries, using an expected return model. The model determines the weighted average return for an investment portfolio based on the target asset allocation and expected future returns for each asset class, which were developed using a building block approach based on observable inflation, available interest rate information, current market characteristics, and historical results. The target allocation of investment assets at December 31, 2020, and the actual allocation at December 31, 2020 and 2019, for Grace’s U.S. qualified pension plans are as follows: Target Percentage of Plan Assets U.S. Qualified Pension Plans Asset Category 2020 2020 2019 Global equities 22 % 23 % 22 % Multi-asset credit 3 % 3 % 3 % Liability-hedging assets 75 % 74 % 75 % Total 100 % 100 % 100 % The following tables present the fair value hierarchy for the U.S. qualified pension plan assets measured at fair value as of December 31, 2020 and 2019. Fair Value Measurements at December 31, 2020, Using Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Common/collective trust funds $ 8.1 $ — $ 8.1 $ — Annuity and immediate participation contracts 21.1 — 21.1 — $ 29.2 $ — $ 29.2 $ — Investments measured at net asset value(1) 971.5 Total Assets at Fair Value $ 1,000.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at net asset value (“NAV”) per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Fair Value Measurements at December 31, 2019, Using Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Common/collective trust funds $ 8.0 $ — $ 8.0 $ — Annuity and immediate participation contracts 20.5 — 20.5 — $ 28.5 $ — $ 28.5 $ — Investments measured at net asset value(1) 927.2 Total Assets at Fair Value $ 955.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Non-U.S. pension plans accounted for approximately 3% of total global pension assets at December 31, 2020 and 2019. Each of these plans, where applicable, follows local requirements and regulations. Some of the local requirements include the establishment of a local pension committee, a formal statement of investment policy and procedures, and routine valuations by plan actuaries. The target allocation of investment assets for non-U.S. pension plans varies depending on the investment goals of the individual plans. The plan assets of the Canadian pension plan represent approximately 95% and 96% of the total non-U.S. pension plan assets at December 31, 2020 and 2019, respectively The expected long-term rate of return on assets for the Canadian pension plan was 4.25% for 2020. The target allocation of investment assets at December 31, 2020, and the actual allocation at December 31, 2020 and 2019, for the Canadian pension plan are as follows: Target Percentage of Plan Assets Canadian Pension Plan Asset Category 2020 2020 2019 Equity securities 23 % 25 % 25 % Bonds 65 % 63 % 62 % Other investments 12 % 12 % 13 % Total 100 % 100 % 100 % The plan assets of the other country plans represent approximately 5% and 4% in the aggregate of total non-U.S. pension plan assets at December 31, 2020 and 2019, respectively. The following tables present the fair value hierarchy for the non-U.S. pension plan assets measured at fair value as of December 31, 2020 and 2019. Fair Value Measurements at December 31, 2020, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Corporate bonds $ 0.5 $ — $ 0.5 $ — Insurance contracts and other investments 0.5 — 0.5 — Cash 0.2 0.2 — — $ 1.2 $ 0.2 $ 1.0 $ — Investments measured at net asset value(1) 27.5 Total Assets at Fair Value $ 28.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Fair Value Measurements at December 31, 2019, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Corporate bonds $ 0.4 $ — $ 0.4 $ — Insurance contracts and other investments 0.5 — 0.5 — Cash 0.1 0.1 — — $ 1.0 $ 0.1 $ 0.9 $ — Investments measured at net asset value(1) 24.2 Total Assets at Fair Value $ 25.2 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Plan Contributions and Funding Grace intends to satisfy its funding obligations under the U.S. qualified pension plans and to comply with all of the requirements of the Employee Retirement Income Security Act of 1974 (“ERISA”). For ERISA purposes, funded status is calculated on a different basis than under U.S. GAAP. Based on the U.S. qualified pension plans’ status as of December 31, 2020, there is a $0.5 million minimum required payment under ERISA for 2021. Grace intends to fund non-U.S. pension plans based on applicable legal requirements and actuarial and trustee recommendations. Grace expects to make contributions of approximately $10 million related to its non-U.S. pension plans in 2021.

Other Balance Sheet Accounts

Other Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Other Balance Sheet Accounts	December 31, (In millions) 2020 2019 Other Current Assets Non-trade accounts receivable $ 23.1 $ 24.1 Income taxes receivable (see Note 7) 7.6 4.2 Fair value of currency, interest rate, and commodity contracts (see Note 6) 2.2 15.6 Plant under construction—unconsolidated affiliate (see Note 19) — 173.9 Other current assets 18.3 17.3 $ 51.2 $ 235.1 December 31, (In millions) 2020 2019 Other Current Liabilities Accrued compensation $ 60.6 $ 53.6 Deferred revenue (see Note 17) 33.8 35.0 Fair value of currency, interest rate, and commodity contracts (see Note 6) 21.6 2.6 Liability for dam spillway replacement (see Note 10) 20.3 4.7 Pension liabilities (see Note 8) 15.7 14.8 Environmental contingencies (see Note 10) 13.8 17.8 Operating lease liabilities (see Note 3) 10.1 9.3 Accrued interest (see Note 5) 5.8 13.3 Income taxes payable (see Note 7) 5.1 8.6 Liability to unconsolidated affiliate for plant under construction (see Note 19) — 173.9 Other accrued liabilities 95.1 86.1 $ 281.9 $ 419.7 Accrued compensation includes salaries and wages as well as estimated current amounts due under the annual and long-term incentive programs. December 31, (In millions) 2020 2019 Other Liabilities Environmental contingencies (see Note 10) $ 95.4 $ 97.5 Liability for dam spillway replacement (see Note 10) 69.3 61.7 Fair value of currency and interest rate contracts (see Note 6) 53.9 13.2 Operating lease liabilities (see Note 3) 25.8 26.2 Legacy product liability (see Note 10) 24.0 24.0 Deferred revenue (see Note 17) 23.4 29.5 Retained obligations of divested businesses 12.2 12.7 Deferred income taxes (see Note 7) 10.4 7.5 Asset retirement obligation 9.6 9.4 Unrecognized tax benefits (see Note 7) 3.9 4.1 Other noncurrent liabilities 19.7 22.4 $ 347.6 $ 308.2

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Legacy Matters Over the years, Grace operated numerous types of businesses that are no longer part of its ongoing operations. As Grace divested or otherwise ceased operating these businesses, it retained certain liabilities and obligations, which Grace refers to as legacy liabilities. These liabilities include product, environmental, and other liabilities. Although the outcome of each of the matters discussed below cannot be predicted with certainty, Grace has assessed its risk and has recorded estimated liabilities as required under U.S. GAAP. Legacy Product Liabilities Grace emerged from an asbestos-related Chapter 11 bankruptcy on February 3, 2014 (the “Effective Date”). Under its plan of reorganization, all pending and future asbestos-related claims are channeled for resolution to either a personal injury trust (the “PI Trust”) or a property damage trust (the “PD Trust”). The trusts are the sole recourse for holders of asbestos-related claims. The channeling injunctions issued by the bankruptcy court prohibit holders of asbestos-related claims from asserting such claims directly against Grace. Grace has satisfied all of its financial obligations to the PI Trust. Grace has contingent financial obligations remaining to the PD Trust. With respect to property damage claims related to Grace’s former Zonolite attic insulation product (“ZAI PD Claims”), the PD Trust was funded with $49.4 million (net of $15 million of attorneys’ fees) to pay claims and expenses. Grace is also obligated to make up to 10 contingent deferred payments of $8 million per year to the PD Trust during the 20-year period beginning on February 3, 2019, with each such payment due only if the assets of the PD Trust in respect of ZAI PD Claims fall below $10 million during the preceding year. As of December 31, 2020, the PD Trust has paid out approximately $38 million in ZAI PD Claims and expenses, leaving a balance of approximately $18 million, including the benefit of realized investment gains. Due to the limited claims history, the unique nature of this product, and the uncertainty of future claims patterns, an actuarial analysis was completed to estimate the range of possible future payments. The analysis was conducted by a third-party actuarial firm directed by Grace and using historical claims data provided by the ZAI trustee. Certain key assumptions employed in the analysis were (1) projections of the future number of filed claims, assuming a percentage increase in claims during earlier years and annual decreases in later years; (2) application of historical percentages of claims closed with indemnity payment compared to total closed claims, applied on a regional basis; and (3) application of the average claim payout, which reflects the average indemnity cost per claim closing with payment. As a result of the analysis and taking into account the relative uncertainty of future claims activity, Grace determined that contingent funding obligations beyond 2025 are not reasonably estimable. Grace estimates that the reasonable range of payments over the period of 2021 to 2025 is expected to be between $16 million and $24 million and projects that the first payment could be due as early as 2022. In the 2019 fourth quarter, Grace recorded a $24.0 million liability related to probable future obligations to fund the PD Trust for ZAI PD Claims. Grace’s maximum financial obligation over the next 18 years is $80.0 million, and no single year’s payment can exceed $8.0 million. With respect to other asbestos property damage claims (“Other PD Claims”), claims unresolved as of the Effective Date are to be litigated in the bankruptcy court and any future claims are to be litigated in a federal district court, in each case pursuant to procedures approved by the bankruptcy court. To the extent any such Other PD Claims are determined to be allowed claims, they are to be paid in cash by the PD Trust. Grace is obligated to make a payment to the PD Trust every six months in the amount of any Other PD Claims allowed during the preceding six months plus interest (if applicable) and the amount of PD Trust expenses for the preceding six months (the “PD Obligation”). Grace has not paid any Other PD Claims since emergence. Annual expenses have been approximately $0.2 million per year. The aggregate amount to be paid under the PD Obligation is not capped, and Grace may be obligated to make additional payments to the PD Trust in respect of the PD Obligation. Grace has accrued for those unresolved Other PD Claims that it believes are probable and estimable. Grace has not accrued for other unresolved or unasserted Other PD Claims as it does not believe that payment is probable. All payments to the PD Trust required after the Effective Date are secured by the Company’s obligation to issue 77,372,257 shares of Company common stock to the PD Trust in the event of default, subject to customary anti-dilution provisions. This summary of the commitments and contingencies related to the Chapter 11 proceeding does not purport to be complete and is qualified in its entirety by reference to the plan of reorganization and the exhibits and documents related thereto, which have been filed with the SEC and are readily available on the internet at www.sec.gov. Legacy Environmental Liabilities Grace is subject to loss contingencies resulting from extensive and evolving federal, state, local and foreign environmental laws and regulations relating to its manufacturing operations. Grace has procedures in place to minimize such contingencies; nevertheless, it has liabilities associated with past operations and additional claims may arise in the future, which may be material. To address its legacy liabilities, Grace accrues for anticipated costs of response efforts where an assessment has indicated that a probable liability has been incurred and the cost can be reasonably estimated. These accruals do not take into account any discounting for the time value of money. Grace’s environmental liabilities are reassessed regularly and adjusted when circumstances become better defined or response efforts and their costs can be better estimated, typically as a matter moves through the life-cycle of environmental investigation and remediation. These liabilities are evaluated based on currently available information relating to the nature and extent of contamination, risk assessments, feasibility of response actions, and apportionment amongst other potentially responsible parties, all evaluated in light of prior experience. At December 31, 2020, Grace’s estimated liability for legacy environmental response costs totaled $109.2 million, compared with $115.3 million at December 31, 2019, and was included in “other current liabilities” and “other liabilities” in the Consolidated Balance Sheets. These amounts are based on agreements in place or on Grace’s estimate of costs where no formal remediation plan or agreement to pay exists, yet there is sufficient information to estimate response costs. Grace recorded pre-tax charges of $1.6 million, $1.7 million, and $73.8 million for legacy environmental matters in 2020, 2019, and 2018, respectively, which is included in “costs related to legacy matters” in the Consolidated Statements of Operations. Vermiculite-Related Matters Grace purchased a vermiculite mine in Libby, Montana, in 1963 and operated it until 1990. Vermiculite concentrate from the Libby mine was used in the manufacture of attic insulation and other products. Some of the vermiculite ore contained naturally occurring asbestos. Grace is engaged with the U.S. Environmental Protection Agency (the “EPA”) and other federal, state and local governmental agencies in a remedial investigation and feasibility study (“RI/FS”) of the Libby mine and the surrounding area, known as Operable Unit 3 (“OU3”). The RI/FS will study the areas within OU3 requiring remediation and will identify possible remedial action alternatives. Possible remedial actions within OU3 are wide-ranging, from institutional controls such as land use restrictions, to more active measures involving soil removal, containment projects, or other protective measures. As part of the RI/FS process, Grace contracted an engineering and consulting firm to develop a range of possible remedial alternatives and associated cost estimates for OU3. Based on this work, Grace recorded a pre-tax charge of $70.0 million during the three months ended September 30, 2018, for the estimated costs of remediation of OU3. Grace believes that this amount should provide for a protective remedy meeting the statutory requirements of the Comprehensive Environmental Response, Compensation, and Liability Act. The estimated costs of remediation are preliminary and consist of several components, each of which may vary significantly as the remedial alternatives are further developed. It is reasonably possible that the ultimate costs of remediation could range between $30 million and $170 million. Grace is working closely with the EPA, and the ultimate remedy will be determined by the EPA after the RI/FS is finalized. Such remedy will be set forth in a Record of Decision (“ROD”) that is currently expected to be issued by the EPA no earlier than 2024. Costs associated with the more active remedial alternatives would be expected to be incurred over a decade or more. Grace will reevaluate its estimated liability as remedial alternatives evolve based on further work by the engineering and consulting firm and discussions with the EPA as the RI/FS process moves toward a ROD. Technical memoranda expected prior to the issuance of the ROD may provide insight into the likely remedial alternatives ultimately selected, allowing Grace to update its cost of remediation estimate. Depending on the remedial alternatives that the EPA selects in the ROD, the total cost of remediating OU3 may exceed Grace’s current estimate by material amounts. The amounts set forth above do not include possible liability for natural resources damage. Based on ecological studies conducted by the EPA, Grace does not believe that natural resources damage has occurred. However, if a party were to be successful in asserting a natural resources damage claim, liability related to such obligation could be material. Grace has cooperated with the EPA in investigating and remediating a number of formerly owned or operated sites that processed Libby vermiculite into finished products. Grace has recorded a liability for remaining expected response costs, including costs for EPA oversight and potential future site remediation, where a review has indicated that liability is probable and the cost is estimable. The EPA may commence additional investigations in the future at other sites that processed Libby vermiculite. Liability for unaccrued additional investigation and remediation costs is probable but not yet estimable, and could be material. Grace recorded pre-tax charges of $0.1 million, $0.0 million, and $70.2 million in 2020, 2019, and 2018, respectively, for future costs related to vermiculite-related matters. Grace’s estimated liability for response costs that are currently estimable for OU3 and vermiculite processing sites outside of Libby at December 31, 2020 and 2019, totaled $71.2 million and $76.0 million, respectively. It is possible that Grace’s ultimate liability for these vermiculite-related matters will exceed current estimates by material amounts. Non-Vermiculite-Related Environmental Matters Grace recorded pre-tax charges of $1.5 million, $1.7 million, and $3.6 million to increase non-vermiculite-related environmental reserves in 2020, 2019, and 2018, respectively. At December 31, 2020, Grace’s estimated legacy environmental liability for response costs at sites not related to its former vermiculite mining and processing activities totaled $38.0 million, compared with $39.3 million at December 31, 2019. This liability relates to Grace’s former businesses or operations, including its share of liability at off-site disposal facilities. Grace’s estimated liability is based upon regulatory requirements and environmental conditions at each site. As Grace receives new information, its estimated liability may change materially. Other Legacy Liabilities Beginning in 1971, as part of implementing a wet milling process at the Libby, Montana, vermiculite mine, Grace constructed a dam at the mine property that now prevents vermiculite ore tailings from moving into nearby creeks and rivers. Ongoing operation of the dam is regulated by the Montana Department of Natural Resources and Conservation (“DNRC”). In April 2019, the DNRC renewed the permit necessary for operation of the dam. Grace is legally obligated to operate the dam and construct a new spillway in accordance with the latest permit conditions. Construction of the new dam spillway at the former mine site is a key element of Grace’s overall remediation strategy. The project includes both an upper spillway and a lower spillway that are being managed as two separate projects with different engineering design and construction timelines. In 2019, Grace contracted a third-party engineering and consulting firm to develop an initial range of cost estimates for the total project. Based on this work, Grace recorded a liability of $68.0 million in 2019 for the estimated costs of the project. These costs were preliminary and subject to change as new information becomes available, including defining the final scope of the projects through the contract bidding process. During the three months ended September 30, 2020, Grace completed a review of contractor bids for the replacement of the upper spillway and increased its cost estimate for this portion of the project by $27.0 million, bringing the estimate for the total project to $95.0 million. Regarding the lower spillway, final engineering will be completed and submitted to the state of Montana for design approval in 2021, after which Grace will seek contract bids for this portion of the project. Grace believes it is reasonably possible that the ultimate costs of the two spillway projects could range between $80 million and $120 million. As Grace receives new information, its estimated liability may change materially. Construction will begin in 2021 and is expected to take three to four years. Commercial and Financial Commitments and Contingencies Purchase Commitments Grace uses purchase commitments to ensure supply and to minimize the volatility of major components of direct manufacturing costs including natural gas, certain metals, rare earths, and other materials. Such commitments are for quantities that Grace fully expects to use in its normal operations. Guarantees and Indemnification Obligations Grace is a party to many contracts containing guarantees and indemnification obligations. These contracts primarily consist of: • Product warranties with respect to certain products sold to customers in the ordinary course of business. These warranties typically provide that products will conform to specifications. Grace accrues a warranty liability on a transaction-specific basis depending on the individual facts and circumstances related to each sale. • Performance guarantees offered to customers under certain licensing arrangements. Grace has not established a liability for these arrangements based on past performance. • Licenses of intellectual property by Grace to third parties in which Grace has agreed to indemnify the licensee against third party infringement claims. • Contracts providing for the sale or spin-off of a former business unit or product line in which Grace has agreed to indemnify the buyer or resulting entity against certain liabilities related to activities prior to the closing of the transaction, including environmental, tax, and employee liabilities. • Indemnification obligations of Grace as a tenant of real property leases; and guarantees of real property lease obligations of third parties, typically arising out of (a) leases entered into by former subsidiaries of Grace, or (b) the assignment or sublease of a lease by Grace to a third party. Financial Assurances Financial assurances have been established for a variety of purposes, including insurance and environmental matters, trade-related commitments and other matters. At December 31, 2020, Grace had gross financial assurances issued and outstanding of $141.1 million, composed of $77.8 million of surety bonds issued by various insurance companies and $63.3 million of standby letters of credit and other financial assurances issued by various banks.

Restructuring Expenses and Repo

Restructuring Expenses and Repositioning Expenses	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Restructuring Expenses and Repositioning Expenses	Restructuring Expenses Restructuring costs in 2020 primarily related to an increase in estimated contractual costs related to a 2018 plant exit. Costs in 2019 primarily related to severance costs pertaining to the idling of our methanol-to-olefins (“MTO”) manufacturing facility, which were substantially paid in 2019. Costs in 2018 primarily related to the closure of two small manufacturing plants, the activities from which were moved to larger, more cost-effective plants as part of Grace’s strategy to capture synergies from catalysts acquisitions. These costs are included in “restructuring and repositioning expenses” in the Consolidated Statements of Operations, and are not included in segment operating income. The following table presents restructuring expenses by reportable segment for the years ended December 31, 2020, 2019, and 2018. Year Ended December 31, (In millions) 2020 2019 2018 Catalysts Technologies $ 1.8 $ 1.6 $ 13.7 Materials Technologies 0.1 1.0 0.5 Corporate — — (0.2) Total restructuring expenses $ 1.9 $ 2.6 $ 14.0 Substantially all costs related to the restructuring programs are expected to be paid by June 30, 2023, but could be paid earlier subject to negotiations around certain plant exit costs. The following table presents components of the change in the restructuring liability for the years ended December 31, 2020, 2019, and 2018: (In millions) Total Balance, December 31, 2017 $ 6.7 Accruals for severance and other costs 10.1 Payments (6.1) Balance, December 31, 2018 $ 10.7 Accruals for severance and other costs 2.6 Payments (10.2) Currency translation adjustments and other 0.7 Balance, December 31, 2019 $ 3.8 Accruals for severance and other costs 3.2 Payments (3.1) Balance, December 31, 2020 $ 3.9 Repositioning Expenses Repositioning expenses for the years ended December 31, 2020, 2019, and 2018 were $35.0 million, $11.1 million, and $32.4 million respectively. During 2020, Grace implemented changes to its Refining Technologies manufacturing operations and global footprint to drive capital and operating efficiencies and to support global growth. Grace, in agreement with its local joint venture partner, discontinued the previously announced project to build a full-scale fluid catalytic cracking catalysts plant in the Middle East. As a result, repositioning expenses in 2020 included a charge of $19.7 million to write off engineering and site costs. Repositioning expenses in 2020 also included $7.2 million in costs related to our review of strategic alternatives. In 2020, 2019, and 2018, Grace incurred expenses related to a multi-year program to transform manufacturing and business processes to extend Grace’s competitive advantages and improve its cost position. Expenses in 2018 also included $11.7 million of severance and stock compensation costs related to employee separations and write-offs of $8.5 million of previously capitalized plant engineering costs as a result of terminating a manufacturing plant expansion project no longer necessary due to the polyolefin catalysts acquisition (see Note 20). Excluding asset write-offs and stock compensation costs, substantially all of these costs have been or are expected to be settled in cash.

Other Expense, net

Other Expense, net	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Other (Income) Expense, net	Components of other (income) expense, net are as follows: Year Ended December 31, (In millions) 2020 2019 2018 Defined benefit pension (income) expense other than service cost $ 79.5 $ 79.9 $ (27.8) Business interruption insurance recoveries (16.3) (10.7) — Hurricane-related costs 13.2 — — Net (gain) loss on sales of investments and disposals of assets 5.9 4.5 4.9 Third-party acquisition-related costs 5.2 3.6 7.3 Currency transaction effects (0.1) (0.8) (3.6) Other miscellaneous (income) expense 1.6 4.1 (4.0) Total other (income) expense, net $ 89.0 $ 80.6 $ (23.2) During 2020, Hurricane Laura caused severe and widespread damage to Lake Charles, Louisiana, and surrounding communities, including catastrophic damage to the regional power grid. The hurricane-related costs were primarily due to on-site power generation, incremental operations and logistics costs to supply customers during the outage, temporary housing and employee assistance, and property damage and clean-up. In addition to the amount shown above, Grace’s equity in earnings from unconsolidated affiliate was reduced by $1.9 million due to hurricane-related costs incurred by the joint venture. In July 2019, a North American FCC catalysts customer filed for bankruptcy protection after announcing it would not resume refinery operations following a fire in its refinery. Grace received $16.3 million during the six months ended June 30, 2020, under its business interruption insurance policy. Including the $8.0 million received in the 2019 fourth quarter, Grace received $24.3 million of insurance recoveries related to this event, reflecting approximately eight quarters of the impact of the incident on earnings. This claim has been fully resolved.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Other Comprehensive Income (Loss)	The following tables present the pre-tax, tax, and after-tax components of Grace’s other comprehensive income (loss) for the years ended December 31, 2020, 2019, and 2018: Year Ended December 31, 2020 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (0.5) $ 0.1 $ (0.4) Currency translation adjustments (53.6) 3.7 (49.9) Gain (loss) from hedging activities 1.6 (0.8) 0.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (52.5) $ 3.0 $ (49.5) Year Ended December 31, 2019 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (0.9) $ 0.2 $ (0.7) Currency translation adjustments 18.5 (2.0) 16.5 Gain (loss) from hedging activities (7.0) 2.1 (4.9) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 10.6 $ 0.3 $ 10.9 Year Ended December 31, 2018 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (1.2) $ 0.3 $ (0.9) Currency translation adjustments 34.6 (2.2) 32.4 Gain (loss) from hedging activities (10.0) 4.3 (5.7) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 23.4 $ 2.4 $ 25.8 The following table presents the changes in accumulated other comprehensive income (loss), net of tax, for the years ended December 31, 2020, 2019, and 2018: Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Balance, December 31, 2017 $ 0.9 $ 41.6 $ (2.6) $ 39.9 OCI before reclassifications — 32.4 11.1 43.5 Amounts reclassified from accumulated OCI (0.9) — (16.8) (17.7) Net current-period other comprehensive income (loss) (0.9) 32.4 (5.7) 25.8 Effect of adopting ASU 2018-02 0.2 2.2 (0.2) 2.2 Balance, December 31, 2018 $ 0.2 $ 76.2 $ (8.5) $ 67.9 OCI before reclassifications — 16.5 14.0 30.5 Amounts reclassified from accumulated OCI (0.7) — (18.9) (19.6) Net current-period other comprehensive income (loss) (0.7) 16.5 (4.9) 10.9 Balance, December 31, 2019 $ (0.5) $ 92.7 $ (13.4) $ 78.8 OCI before reclassifications — (49.9) (33.7) (83.6) Amounts reclassified from accumulated OCI (0.4) — 34.5 34.1 Net current-period other comprehensive income (loss) (0.4) (49.9) 0.8 (49.5) Balance, December 31, 2020 $ (0.9) $ 42.8 $ (12.6) $ 29.3 Grace is a global enterprise operating in many countries with local currency generally deemed to be the functional currency for accounting purposes. The currency translation amount represents the adjustments necessary to translate the balance sheets valued in local currencies to the U.S. dollar as of the end of each period presented, and to translate revenues and expenses at average exchange rates for each period presented, as well as amounts related to net investment hedges. See Note 6 for a discussion of hedging activities. See Note 8 for a discussion of pension plans.

Shareholders' Equity (Deficit)

Shareholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Shareholders' Equity	Under its Amended and Restated Certificate of Incorporation, the Company is authorized to issue 300,000,000 shares of common stock, $0.01 par value per share. As of December 31, 2020, the W. R. Grace & Co. 2018 Stock Incentive Plan (together with the 2014 Stock Incentive Plan, collectively, the “Stock Incentive Plans”) had 6,474,722 shares of unissued stock reserved for issuance in the event of the exercise of stock options or the issuance or settlement of stock-based compensation or awards. Shares issuable upon the exercise of stock options or the issuance or settlement of stock-based compensation or awards are covered by reissuing treasury stock, to the extent available; otherwise they are covered through newly issued shares. In 2020, 15,960 common shares were issued to members of the Board of Directors, in partial payment of their annual retainer, and 112,344 shares were issued to settle vested PBUs and vested tranches of RSUs. The following table sets forth information relating to common stock activity for the years ended December 31, 2020, 2019, and 2018: (In millions, except shares) Number of Shares Aggregate Proceeds Balance of outstanding shares, December 31, 2017 67,780,410 Stock options exercised 243,502 $ 6.7 Shares issued 72,590 Shares forfeited through net share exercise (132,393) Shares repurchased (1,171,141) Balance of outstanding shares, December 31, 2018 66,792,968 Stock options exercised 388,174 $ 19.1 Shares issued 94,796 Shares forfeited through net share exercise (130,256) Shares repurchased (409,769) Balance of outstanding shares, December 31, 2019 66,735,913 Stock options exercised — $ — Shares issued 128,304 Shares repurchased (673,807) Balance of outstanding shares, December 31, 2020 66,190,410

Stock Incentive Plans

Stock Incentive Plans	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock Incentive Plans	The Stock Incentive Plans are administered by the Compensation Committee of the Board of Directors. Pursuant to the Stock Incentive Plans, the Company maintains Long-term Incentive Plans (the “LTIP”) under which it issues RSUs, PBUs, and stock options. The Company has granted nonstatutory stock options to certain key employees under the Stock Incentive Plans. Stock options are generally non-qualified and are at exercise prices not less than 100% of the average per share fair market value on the date of grant. Stock-based compensation awards granted under the Company’s stock incentive plans are generally subject to a vesting period from the date of the grant ranging from 1 - 3 years. Currently outstanding options expire on various dates through May 2030. On May 9, 2018, the Company’s stockholders approved the W. R. Grace & Co. 2018 Stock Incentive Plan. Under this new plan, stock options have a 10-year life. The Company began issuing stock-based compensation awards from this plan in the second half of 2018. The Company’s prior grants were issued under the previous plan in which options have a 5-year life. The following table sets forth information relating to such options during 2020, 2019, and 2018. Number of Average Weighted- Balance, December 31, 2017 1,813,450 $ 72.04 Options exercised (243,502) 61.92 Options forfeited (90,862) 69.82 Options terminated (33,481) 75.07 Options granted 428,190 67.36 $ 12.30 Balance, December 31, 2018 1,873,795 72.34 Options exercised (388,174) 74.33 Options forfeited (35,216) 71.21 Options terminated (74,583) 77.30 Options granted 189,787 78.11 $ 17.94 Balance, December 31, 2019 1,565,609 72.30 Options exercised — — Options forfeited (26,696) 60.26 Options terminated (473,582) 76.67 Options granted 348,005 55.34 $ 9.64 Balance, December 31, 2020 1,413,336 66.89 The following is a summary of nonvested option activity for the year ended December 31, 2020. Number Of Weighted- Nonvested options outstanding at beginning of year 506,593 $ 14.81 Granted 348,005 9.64 Vested (269,148) 13.93 Forfeited (20,787) 9.90 Nonvested options outstanding at end of year 564,663 12.16 As of December 31, 2020, the intrinsic value (the difference between the exercise price and the market price) for options outstanding was immaterial and for options exercisable was zero. The total intrinsic value of all options exercised during the years ended December 31, 2019 and 2018 was $0.8 million and $1.6 million, respectively. No options were exercised in 2020. A summary of our stock options outstanding and exercisable at December 31, 2020, follows: Exercise Price Range Number Outstanding Number Exercisable Outstanding Weighted- Average Remaining Contractual Life (Years) Exercisable Weighted- Average Exercise Price $40 - $50 1,802 — 9.35 $ — $50 - $60 326,051 — 9.17 — $60 - $70 640,777 522,178 1.31 67.92 $70 - $80 444,706 326,495 3.90 72.65 1,413,336 848,673 At December 31, 2020, the weighted-average remaining contractual term of all options outstanding and exercisable was 3.95 years. Options Granted For the years ended December 31, 2020, 2019, and 2018, the Company recognized non-cash stock-based compensation expense with respect to stock option grants of $2.8 million, $3.1 million, and $5.8 million, respectively, which is included in “selling, general and administrative expenses” in the Consolidated Statements of Operations. The actual tax benefit realized from stock option arrangements totaled $0.6 million, $1.9 million, and $2.2 million for the years ended December 31, 2020, 2019 and 2018, respectively. The Company values options using the Black-Scholes option-pricing model, which was developed for use in estimating the fair value of traded options. The risk-free rate is based on the U.S. Treasury yield curve published as of the grant date, with maturities approximating the expected term of the options. The expected term of the options is estimated using the simplified method as allowed by ASC 718-20, whereby the average between the vesting period and contractual term is used. The expected volatility was estimated using actual Company stock volatility. The following summarizes the weighted average assumptions used for estimating the fair value of stock options granted during 2020, 2019, and 2018, respectively. 2020 2019 2018 Expected volatility 22.7% - 29.4% 22.7% - 23.1% 22.9% - 24.4% Weighted average expected volatility 22.9% 23.0% 23.7% Expected term 5.5 - 6.5 years 5.5 - 6.5 years 3.0 - 6.5 years Risk-free rate 1.18% 2.58% 2.55% Dividend yield 2.2% 1.4% 1.4% Total unrecognized stock-based compensation expense at December 31, 2020, was $2.1 million, and the weighted-average period over which this expense will be recognized is 0.8 of a year. Restricted Stock and Performance Based Units In 2019, the Company modified a majority of its 2017 and 2018 cash-settled LTIP awards to be stock-settled. The following is a summary of RSUs and PBUs awarded under the LTIP. 2020 2019 2018 PBUs granted under the LTIP 120,161 88,174 93,216 RSUs granted under the LTIP 68,658 57,900 86,698 Shares covered by awards forfeited under the LTIP 17,250 17,323 44,279 Weighted average grant date fair value of PBUs $55.33 $78.11 $67.39 Weighted average grant date fair value of RSUs $55.05 $76.91 $67.54 Approximate percentage of awards expected to settle in common stock(1) 96 % 96 % 94 % Approximate percentage of awards expected to settle in cash(1) 4 % 4 % 6 % ___________________________________________________________________________________________________________________ (1) Assumes full vesting. The PBUs cliff vest after the completion of the performance periods ending December 31, 2022, 2021, and 2020. The RSUs vest in three equal annual installments. Vesting for all awards is subject to continued employment through the payment date (subject to certain exceptions for retirement, death or disability, change in control scenarios, and in the discretion of the Compensation Committee). PBUs and RSUs are recorded at fair value at the date of grant. The common stock settled portion is considered an equity award with the payout being valued based on the Company’s stock price on the grant date. The cash settled portion of the award is considered a liability award with payout being remeasured each reporting period based on the Company’s current stock price. PBU equity awards are remeasured each reporting period based on the expected payout of the award, which may range from 0% to 200% of the targets for such awards; therefore, these portions of the awards are subject to volatility until the payout is finally determined at the end of

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings Per Share	The following table shows a reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share. Year Ended December 31, (In millions, except per share amounts) 2020 2019 2018 Numerators Net income (loss) attributable to W. R. Grace & Co. shareholders $ (1.8) $ 126.3 $ 167.6 Denominators Weighted average common shares—basic calculation 66.3 66.8 67.2 Dilutive effect of employee stock options — 0.1 0.1 Weighted average common shares—diluted calculation 66.3 66.9 67.3 Basic earnings per share $ (0.03) $ 1.89 $ 2.49 Diluted earnings per share $ (0.03) $ 1.89 $ 2.49 There were approximately 1.6 million, 1.0 million and 1.7 million anti-dilutive options outstanding for the years ended December 31, 2020, 2019, and 2018, respectively. On February 8, 2017, the Company announced that its Board of Directors had authorized a share repurchase program of up to $250 million. On February 28, 2020, Grace announced that its Board of Directors had increased its share repurchase authorization to $250 million, including approximately $83 million remaining under the previously announced program. The timing of the repurchases and the actual amount repurchased will depend on a variety of factors, including the market price of the Company’s shares, strategic priorities for the deployment of capital, and general market and economic conditions. During 2020, 2019, and 2018, the Company repurchased 673,807; 409,769; and 1,171,141 shares of Company common stock for $40.4 million, $29.8 million, and $80.0 million, respectively, pursuant to the terms of the share repurchase program. As of December 31, 2020, $235.0 million remained under the current authorization.

Revenues Revenues (Notes)

Revenues Revenues (Notes)	12 Months Ended
	Dec. 31, 2020
Revenues [Abstract]
Revenues [Text Block]	Grace generates revenues from customer arrangements primarily by manufacturing and delivering specialty chemicals and specialty materials, and by licensing technology, through its two reportable segments. See Note 18 for additional information about Grace’s reportable segments. Disaggregation of Revenue The following tables present Grace’s revenues by geography and product group, within its respective reportable segments, for the years ended December 31, 2020, 2019, and 2018. Year Ended December 31, 2020 North America Europe Middle East Africa (EMEA) Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 172.3 $ 231.7 $ 201.1 $ 16.5 $ 621.6 Refining Catalysts 216.6 279.1 120.4 33.7 649.8 Total Catalysts Technologies $ 388.9 $ 510.8 $ 321.5 $ 50.2 $ 1,271.4 Pharma/Consumer $ 61.5 $ 60.9 $ 19.8 $ 20.3 $ 162.5 Coatings 25.4 66.6 35.8 9.7 137.5 Chemical process 28.5 69.4 36.1 6.6 140.6 Other 4.1 13.3 0.3 0.1 17.8 Total Materials Technologies $ 119.5 $ 210.2 $ 92.0 $ 36.7 $ 458.4 Total Grace $ 508.4 $ 721.0 $ 413.5 $ 86.9 $ 1,729.8 Year Ended December 31, 2019 North America EMEA Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 191.4 $ 283.0 $ 213.7 $ 17.2 $ 705.3 Refining Catalysts 291.4 288.4 171.7 39.9 791.4 Total Catalysts Technologies $ 482.8 $ 571.4 $ 385.4 $ 57.1 $ 1,496.7 Pharma/Consumer $ 45.2 $ 59.1 $ 20.1 $ 20.2 $ 144.6 Coatings 25.9 67.8 36.9 9.2 139.8 Chemical process 38.1 79.1 32.3 6.6 156.1 Other 5.8 14.2 0.7 0.2 20.9 Total Materials Technologies $ 115.0 $ 220.2 $ 90.0 $ 36.2 $ 461.4 Total Grace $ 597.8 $ 791.6 $ 475.4 $ 93.3 $ 1,958.1 Year Ended December 31, 2018 North America EMEA Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 192.6 $ 255.4 $ 193.2 $ 20.3 $ 661.5 Refining Catalysts 282.8 266.0 193.4 59.8 802.0 Total Catalysts Technologies $ 475.4 $ 521.4 $ 386.6 $ 80.1 $ 1,463.5 Pharma/Consumer $ 36.2 $ 58.0 $ 19.0 $ 19.4 $ 132.6 Coatings 28.1 75.3 43.3 8.7 155.4 Chemical process 35.2 81.6 32.2 8.3 157.3 Other 6.8 15.9 0.4 0.2 23.3 Total Materials Technologies $ 106.3 $ 230.8 $ 94.9 $ 36.6 $ 468.6 Total Grace $ 581.7 $ 752.2 $ 481.5 $ 116.7 $ 1,932.1 Contract Balances Grace invoices customers for product sales once performance obligations have been satisfied, generally at the point of delivery, at which point payment becomes unconditional. Accordingly, Grace’s product sales contracts generally do not give rise to material contract assets or liabilities under ASC 606; however, from time to time certain customers may pay in advance, which results in a contract liability. In the technology licensing business, Grace typically invoices licensees at the time that contractual milestones are achieved. However, in respect of the milestone billings, Grace is frequently obligated to provide services in future periods, and this results in recording contract liabilities. The following table presents Grace’s deferred revenue balances as of December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Current $ 33.8 $ 35.0 Noncurrent 23.4 29.5 Total $ 57.2 $ 64.5 Grace records deferred revenues when cash payments are received or due in advance of performance. The change in deferred revenue reflects cash payments from customers received or due in advance of satisfying performance obligations, offset by $31.0 million of revenue recognized that was included in the deferred revenue balance as of December 31, 2019. The noncurrent portion of deferred revenue will be recognized as performance obligations under the technology licensing agreements are satisfied, which is expected to be over the next four years. Remaining performance obligations represent the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied). The aggregate amount of the transaction price allocated to remaining performance obligations for such contracts with a duration of more than one year was approximately $148 million as of December 31, 2020, and includes certain amounts reported as deferred revenue above. In accordance with the available practical expedient, Grace does not disclose information about remaining performance obligations that have original expected durations of one year or less, which generally relate to customer prepayments on product sales and are generally satisfied in less than one year. Grace expects to recognize revenue related to remaining performance obligations over several years, as follows: Year Approximate percentage of revenue related to remaining performance obligations recognized 2021 27 % 2022 19 % 2023 17 % 2024 16 % Thereafter through 2030 21 % For the years ended December 31, 2020, 2019, and 2018, revenue recognized from performance obligations related to prior periods was not material. Grace has not capitalized any costs to obtain or fulfill contracts with customers under ASC 606. No material impairment losses have been recognized on any receivables or contract assets arising from contracts with customers.

Operating Segment Information

Operating Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Operating Segment Information	Grace is a global producer of specialty chemicals and specialty materials. Grace’s two reportable business segments are Grace Catalysts Technologies and Grace Materials Technologies. Grace Catalysts Technologies includes catalysts and related products and technologies used in petrochemical, refining, and other chemical manufacturing applications. Advanced Refining Technologies (“ART”), Grace’s joint venture with Chevron U.S.A. Inc. (“Chevron”), is managed in this segment. (See Note 19.) Grace Catalysts Technologies comprises two operating segments, Grace Specialty Catalysts and Grace Refining Technologies, which are aggregated into one reportable segment based upon similar economic characteristics, the nature of the products and production processes, type and class of customer, and channels of distribution. Grace Materials Technologies includes specialty materials, including silica-based and silica-alumina-based materials, used in pharma/consumer, coatings, and chemical process applications. The table below presents information related to Grace’s reportable segments. Only those corporate expenses directly related to the reportable segments are allocated for reporting purposes. All remaining corporate items are reported separately and labeled as such. Grace excludes defined benefit pension expense from the calculation of segment operating income. Grace believes that the exclusion of defined benefit pension expense provides a better indicator of its reportable segment performance as defined benefit pension expense is not managed at a reportable segment level. Grace defines Adjusted EBIT to be net income attributable to W. R. Grace & Co. shareholders adjusted for interest income and expense; income taxes; costs related to legacy matters; restructuring and repositioning expenses and asset impairments; pension costs other than service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits; gains and losses on sales or exits of businesses, product lines, and certain other investments; third-party acquisition-related costs and the amortization of acquired inventory fair value adjustment; gains and losses on modification or extinguishment of debt; the effects of these items on equity in earnings of unconsolidated affiliate; and certain other items that are not representative of underlying trends. Reportable Segment Data Year Ended December 31, (In millions) 2020 2019 2018 Net Sales Catalysts Technologies $ 1,271.4 $ 1,496.7 $ 1,463.5 Materials Technologies 458.4 461.4 468.6 Total $ 1,729.8 $ 1,958.1 $ 1,932.1 Adjusted EBIT Catalysts Technologies segment operating income $ 309.6 $ 466.4 $ 440.9 Materials Technologies segment operating income 85.0 97.8 105.6 Corporate costs (68.0) (72.7) (73.5) Certain pension costs (14.4) (18.4) (15.9) Total $ 312.2 $ 473.1 $ 457.1 Depreciation and Amortization Catalysts Technologies $ 85.3 $ 81.9 $ 81.7 Materials Technologies 15.0 14.2 15.5 Corporate 4.7 4.2 3.6 Total $ 105.0 $ 100.3 $ 100.8 Capital Expenditures Catalysts Technologies $ 107.8 $ 114.6 $ 150.3 Materials Technologies 36.2 68.8 56.1 Corporate 13.6 10.7 9.9 Total $ 157.6 $ 194.1 $ 216.3 Total Assets Catalysts Technologies $ 2,294.9 $ 2,556.1 $ 2,326.6 Materials Technologies 448.2 430.3 375.9 Corporate 1,022.4 946.2 862.8 Total $ 3,765.5 $ 3,932.6 $ 3,565.3 Corporate costs include functional costs and other costs such as professional fees, incentive compensation, and insurance premiums. Certain pension costs include only ongoing costs recognized quarterly, which include service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits. See Note 17 for sales of similar products within each reportable segment. Reconciliation of Reportable Segment Data to Financial Statements Grace Adjusted EBIT for the years ended December 31, 2020, 2019, and 2018 is reconciled below to income (loss) before income taxes presented in the accompanying Consolidated Statements of Operations. Year Ended December 31, (In millions) 2020 2019 2018 Grace Adjusted EBIT $ 312.2 $ 473.1 $ 457.1 Pension MTM adjustment and other related costs, net (94.6) (85.9) 15.2 Loss on early extinguishment of debt (39.4) — (4.8) Costs related to legacy product, environmental and other claims (39.4) (103.5) (82.3) Restructuring and repositioning expenses (36.9) (13.7) (46.4) Inventory write-offs and disposal costs(1) (20.7) (3.6) — Third-party acquisition-related costs (5.2) (3.6) (7.3) Taxes and interest included in equity in earnings of unconsolidated affiliate (0.7) 0.1 (0.4) Benefit plan adjustment — (5.0) — Amortization of acquired inventory fair value adjustment — — (6.9) Interest expense, net (74.9) (74.8) (78.5) Net income (loss) attributable to noncontrolling interests 0.1 0.4 (0.8) Income (loss) before income taxes $ 0.5 $ 183.5 $ 244.9 ___________________________________________________________________________________________________________________ (1) Inventory write-off in 2020 related to the changes in hydroprocessing catalysts manufacturing operations (see Note 2). Inventory write-off in 2019 related to the idling of Grace’s MTO manufacturing facility. Geographic Area Data The table below presents information related to the geographic areas in which Grace operates. Sales are attributed to geographic areas based on the location to which the product is transported. Year Ended December 31, (In millions) 2020 2019 2018 Net Sales United States $ 459.8 $ 540.2 $ 533.8 Canada 48.6 57.6 47.9 Total North America 508.4 597.8 581.7 Europe Middle East Africa 721.0 791.6 752.2 Asia Pacific 413.5 475.4 481.5 Latin America 86.9 93.3 116.7 Total $ 1,729.8 $ 1,958.1 $ 1,932.1 Long-Lived Assets(1) United States $ 799.1 $ 937.9 $ 793.0 Canada 23.2 18.9 16.5 Total North America 822.3 956.8 809.5 Germany 267.4 228.2 172.5 Rest of Europe Middle East Africa 41.0 45.2 48.9 Total Europe Middle East Africa 308.4 273.4 221.4 Asia Pacific 72.2 80.3 72.9 Latin America 5.9 7.2 6.7 Total $ 1,208.8 $ 1,317.7 $ 1,110.5 ___________________________________________________________________________________________________________________ (1) Long-lived assets as of December 31, 2019 and 2018, include properties and equipment and the current asset related to a hydroprocessing catalyst plant to be transferred to ART upon completion. (See Note 19.)

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments and Joint Ventures Disclosure	Unconsolidated Affiliate Grace accounts for its 50% ownership interest in ART, its joint venture with Chevron, using the equity method of accounting. Grace’s investment in ART amounted to $175.5 million and $181.9 million as of December 31, 2020 and 2019, respectively. ART is a private, limited liability company, taxed as a partnership, and accordingly does not have a quoted market price available. During 2020, Grace received dividends of $20.0 million from ART. The table below presents the components of Grace’s “equity in earnings of unconsolidated affiliate” in the Consolidated Statements of Operations. Year Ended December 31, (In millions) 2020 2019 2018 Operating income $ 17.5 $ 28.2 $ 32.7 Depreciation and amortization (3.3) (0.5) (0.5) Interest expense and income taxes (0.7) 0.1 (0.4) Equity in earnings of unconsolidated affiliate 13.5 27.8 31.8 The table below presents summary financial data related to ART’s balance sheet and results of operations. December 31, (In millions) 2020 2019 Summary Balance Sheet information: Current assets $ 286.4 $ 300.7 Noncurrent assets 235.8 237.8 Total assets $ 522.2 $ 538.5 Current liabilities $ 173.0 $ 177.1 Noncurrent liabilities 0.3 0.3 Total liabilities $ 173.3 $ 177.4 Year Ended December 31, (In millions) 2020 2019 2018 Summary Statement of Operations information: Net sales $ 481.9 $ 527.5 $ 487.5 Costs and expenses applicable to net sales 431.4 453.4 410.6 Income before income taxes 28.2 59.0 65.5 Net income 27.0 56.5 64.2 Grace and ART transact business on a regular basis and maintain several agreements in order to operate the joint venture. These agreements and the resulting transactions are treated as related party activities with an unconsolidated affiliate. Product manufactured by Grace for ART is accounted for on a net basis, with a mark-up, which reduces “cost of goods sold” in the Consolidated Statements of Operations. Grace also receives reimbursement from ART for fixed costs; research and development; selling, general and administrative services; and depreciation. Grace records reimbursements against the respective line items in Grace’s Consolidated Statements of Operations. The table below presents summary financial data related to transactions between Grace and ART. Year Ended December 31, (In millions) 2020 2019 2018 Product manufactured for ART $ 261.1 $ 260.8 $ 229.1 Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold 5.1 5.1 4.5 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 54.3 51.1 41.8 The table below presents balances in Grace’s Consolidated Financial Statements related to ART. December 31, (in millions) 2020 2019 Trade accounts receivable $ 28.3 $ 17.5 Other current assets — 173.9 Accounts payable 19.8 37.7 Debt payable within one year 3.5 9.9 Debt payable after one year 22.1 37.5 Other current liabilities — 173.9 The current asset and current liability as of December 31, 2019, in the table above represented spending related to a residue hydroprocessing catalyst production plant that has been constructed in Lake Charles, Louisiana. Grace managed the design and construction of the plant, and the asset was included in “other current assets” in Grace’s Consolidated Balance Sheets until commissioning and start-up activities were completed. Grace had likewise recorded a liability for the transfer of the asset to ART upon completion, included in “other current liabilities” in the Consolidated Balance Sheets. Grace transferred the asset to ART in the 2020 third quarter. Grace and ART maintain an agreement whereby ART loans Grace funds for maintenance capital expenditures at manufacturing facilities used to produce catalysts for ART. Grace makes principal and interest payments on the loans on a monthly basis. These unsecured loans have repayment terms of up to 8 years, unless earlier repayment is demanded by ART. The loans bear interest at the three-month LIBOR plus 1.25%. Grace and Chevron provide lines of credit in the amount of $15.0 million each at a commitment fee of 0.1% of the credit amount. These agreements have been approved by the ART Executive Committee for renewal until February 2022. No amounts were outstanding at December 31, 2020 and 2019. Joint Venture Arrangement In 2018, Grace formed a joint venture in a developing country in Asia. The purpose of the joint venture is to establish a logistics facility and catalyst testing laboratory and to be the exclusive FCC catalysts and additives supplier to certain customers in the country. Grace’s joint venture partner is the parent company of the customers. Grace has an 87.5% ownership interest in the joint venture and consolidates the activities of the entity. Grace’s Consolidated Balance Sheets as of December 31, 2020 and 2019, include trade accounts receivable of $2.2 million and $3.6 million, respectively, from these customers. Grace’s Consolidated Statements of Operations for the years ended December 31, 2020, 2019, and 2018, include $11.3 million, $11.8 million, and $14.0 million, respectively, of revenues from these customers.

Acquisition (Notes)

Acquisition (Notes)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Rive Technology, Inc. On June 17, 2019, Grace completed the acquisition of the business and assets of Rive Technology, Inc. for $22.8 million, with an additional $2.0 million holdback payment remitted in the three months ended September 30, 2020. The business is included in the Refining Technologies operating segment of the Catalysts Technologies reportable segment. The acquisition included Rive’s MOLECULAR HIGHWAY ® zeolite technology for catalytic processes, which allows Grace to offer a broader spectrum of products for converting crude oil to petrochemical feedstocks. Polyolefin catalysts business of Albemarle Corporation On April 3, 2018, using cash on hand and borrowings under the Credit Agreement, Grace acquired the assets of the polyolefin catalysts business of Albemarle Corporation. Grace acquired the business for $418.0 million, net of cash acquired and including customary post-closing adjustments. The business is included in the Specialty Catalysts operating segment of the Catalysts Technologies reportable segment. The acquisition is complementary to Grace’s existing specialty catalysts business and strengthens Grace’s commercial relationships, catalysts technology portfolio, and manufacturing network.

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Summary Information (Unaudited)	(In millions, except per share amounts) March 31 June 30 September 30(2) December 31(3) 2020 Net sales $ 421.5 $ 418.7 $ 419.4 $ 470.2 Gross profit 159.6 119.3 156.4 181.2 Net income (loss) 42.1 (9.6) 6.7 (40.9) Net income (loss) attributable to W. R. Grace & Co. shareholders 42.0 (7.3) 7.0 (43.5) Net income (loss) per share:(1) Basic earnings (loss) per share: $ 0.63 $ (0.11) $ 0.11 $ (0.66) Diluted earnings (loss) per share: 0.63 (0.11) 0.11 (0.66) Dividends declared per share 0.30 0.30 0.30 0.30 ___________________________________________________________________________________________________________________ (1) Per share results for the four quarters may differ from full-year per share results, as a separate computation of the weighted average number of shares outstanding is made for each quarter presented. (2) Third quarter “net income (loss),” “net income (loss) attributable to W. R. Grace & Co. shareholders,” and the related earnings per share data include the effects of a pre-tax charge of $27.0 million for estimated costs to construct a new dam spillway at the former vermiculite mine site in Libby, Montana, as well as a $39.4 million loss on early extinguishment of debt. (3) Fourth quarter “net income (loss),” “net income (loss) attributable to W. R. Grace & Co. shareholders,” and the related earnings per share data include the effects of the annual pension mark-to-market adjustment, as well as charges related to legacy items (see Note 10). (In millions, except per share amounts) March 31(2) June 30 September 30 December 31(3) 2019 Net sales $ 469.5 $ 513.6 $ 470.5 $ 504.5 Gross profit 188.6 209.4 191.0 204.7 Net income (loss) 24.6 76.4 53.8 (28.1) Net income (loss) attributable to W. R. Grace & Co. shareholders 24.7 76.2 53.7 (28.3) Net income (loss) per share:(1) Basic earnings (loss) per share: $ 0.37 $ 1.14 $ 0.81 $ (0.42) Diluted earnings (loss) per share: 0.37 1.14 0.80 (0.42) Dividends declared per share 0.27 0.27 0.27 0.27 ___________________________________________________________________________________________________________________ (1) Per share results for the four quarters may differ from full-year per share results, as a separate computation of the weighted average number of shares outstanding is made for each quarter presented. (2) First quarter “net income (loss),” “net income (loss) attributable to W. R. Grace & Co. shareholders,” and the related earnings per share data include the effects of a pre-tax charge of $45.0 million for estimated costs to construct a new dam spillway at the former vermiculite mine site in Libby, Montana. (3) Fourth quarter “net income (loss),” “net income (loss) attributable to W. R. Grace & Co. shareholders,” and the related earnings per share data include the effects of the annual pension mark-to-market adjustment, as well as charges related to legacy items (see Note 10).

SCHEDULE II-VALUATION AND QUALI

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	12 Months Ended
	Dec. 31, 2020
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	W. R. GRACE & CO. AND SUBSIDIARIES FINANCIAL STATEMENT SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS For the Year Ended December 31, 2020 (In millions) Balance at beginning of period Additions charged to costs and expenses Deductions Other, Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable $ 13.7 $ 0.6 $ (12.1) $ 0.1 $ 2.3 Valuation allowance for deferred tax assets(2) 24.1 15.5 (0.9) — 38.7 For the Year Ended December 31, 2019 (In millions) Balance at beginning of period Additions charged to costs and expenses Deductions Other, Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable $ 12.0 $ 3.2 $ (1.5) $ — $ 13.7 Valuation allowance for deferred tax assets(3) 19.9 9.2 (5.0) — 24.1 For the Year Ended December 31, 2018 (In millions) Balance at beginning of period Additions charged to costs and expenses Deductions Other, Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable $ 12.0 $ — $ — $ — $ 12.0 Valuation allowance for deferred tax assets(4) 12.0 10.7 (2.8) — 19.9 ___________________________________________________________________________________________________________________ (1) Effects of currency translation. (2) The valuation allowance increased $14.6 million from December 31, 2019, to December 31, 2020. The increase was primarily due to projected consolidated taxable income, causing the expiration of foreign tax credits in 2021. (3) The valuation allowance increased $4.2 million from December 31, 2018, to December 31, 2019. The increase was primarily due to the projected taxable income in certain foreign jurisdictions. (4) The valuation allowance increased $7.9 million from December 31, 2017, to December 31, 2018. The increase was primarily due to changes in expected foreign tax credit utilization.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	On February 25, 2021, Grace entered into a definitive agreement to acquire the Fine Chemistry Services business of Albemarle Corporation (“Albemarle”) for approximately $570 million, including $300 million to be paid in cash at closing and $270 million to be funded through the issuance to Albemarle of non-participating preferred equity of a newly created wholly owned Grace subsidiary. The cash portion of the transaction is expected to be funded through a combination of debt and cash on hand. This acquisition would strengthen and expand Grace’s existing pharma portfolio, within the Materials Technologies segment. The transaction is subject to customary closing conditions, including receipt of certain regulatory approvals.

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Lessee, Leases [Policy Text Block]	Leases Grace leases certain real estate, office space, vehicles, railcars, and plant and office equipment, substantially all of which are accounted for as operating leases. Finance lease costs and sublease income are not material. Many of Grace’s leases contain renewal options, which are exercisable at Grace’s discretion and may be included in lease terms when they are reasonably certain to be exercised. Grace’s lease agreements do not contain material restrictive covenants or material residual value guarantees. Grace has elected not to recognize in the Consolidated Balance Sheets short-term leases, which are those with an initial term of 12 months or less. Grace has also elected not to separate lease and non-lease components. These elections apply to all asset classes. Where available, Grace uses the interest rate implicit in the lease to calculate the estimated present value of lease payment obligations. Where such a rate is not available, Grace uses an incremental borrowing rate based on credit-adjusted and term-specific discount rates, using a third-party yield curve.
Principles of Consolidation	The Consolidated Financial Statements include the accounts of Grace and entities as to which Grace maintains a controlling financial interest. Intercompany transactions and balances are eliminated in consolidation. Investments in affiliated companies in which Grace can significantly influence operating and financial policies, but does not have a controlling financial interest, are accounted for under the equity method.Grace conducts a portion of its business through joint ventures with unaffiliated third parties. For joint ventures in which Grace has a controlling financial interest, Grace consolidates the results of such joint ventures in the Consolidated Financial Statements. Grace recognizes a liability for cumulative amounts due to the third parties based on the financial results of the joint ventures, and deducts the amount of income attributable to noncontrolling interests in the measurement of its consolidated net income.
Noncontrolling Interests in Consolidated Entities	Grace conducts a portion of its business through joint ventures with unaffiliated third parties. For joint ventures in which Grace has a controlling financial interest, Grace consolidates the results of such joint ventures in the Consolidated Financial Statements. Grace recognizes a liability for cumulative amounts due to the third parties based on the financial results of the joint ventures, and deducts the amount of income attributable to noncontrolling interests in the measurement of its consolidated net income.
Operating Segments	Grace reports financial results of each of its reportable segments that engage in business activities that generate revenues and expenses and whose operating results are regularly reviewed by Grace’s Chief Executive Officer.
Use of Estimates	The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace’s accounting measurements that are most affected by management’s estimates of future events are: • The effective tax rate and realization values of net deferred tax assets, which depend on projections of future taxable income (see Note 7); • Pension and postretirement liabilities, which depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 8); • Carrying values of goodwill and other intangible assets, which depend on assumptions of future earnings and cash flows (see Note 4 and Note 20); and • Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate obligation, such as litigation and arbitration; and product, environmental, and other legacy liabilities (see Note 10).
Revenue Recognition	Grace generates revenues predominantly from sales of manufactured products to customers and in part from licensing of technology. Under ASC 606, revenue from customer arrangements is recognized when control is transferred to the customer. Product Sales Based on the promises made to customers in product sales arrangements, Grace has a performance obligation to manufacture and deliver products to its customers. Grace makes certain other promises in its customer arrangements that are immaterial in the context of the contracts. Revenue is recognized at amounts based on agreed-upon prices in sales contracts and/or purchase orders. Grace offers various incentives to its product sales customers that result in variable consideration, including but not limited to volume discounts, which reward bulk purchases by lowering the price for future purchases, and volume rebates, which encourage customers to purchase volume levels that would reduce their current prices. These incentives are immaterial in the context of the contracts. For product sales, control is transferred at the point in time at which risk of loss and title have transferred to the customer, which is determined based on shipping terms and contract terms, respectively. Terms of delivery and terms of payment are generally included in customer contracts of sale, order confirmation documents, and invoices. Payment is generally due within 30 to 60 days of invoicing. Grace defers revenue recognition until no other significant Grace performance obligations remain. Grace’s customer arrangements do not contain significant acceptance provisions. Taxes that Grace collects that are assessed by a governmental authority, and that are both imposed on and concurrent with any of its revenue-producing activities, are excluded from revenue. Grace considers shipping and handling activities that it performs as activities to fulfill the sales of its products. Amounts billed for shipping and handling are included in “net sales,” while costs incurred for shipping and handling are included in “cost of goods sold.” Technology Licensing For Grace’s technology licensing business, customer arrangements typically contain multiple deliverables to enable licensees to realize the full benefit of the technology. These deliverables include licensing the technology itself; developing engineering design packages; and providing training, consulting, and technical services. Under these arrangements, the license grant is not a distinct performance obligation, as the licensee only can benefit from the license in conjunction with other integral services such as development of the engineering design package, training, consulting, or technical services provided over the contract period. Therefore, Grace accounts for the license grant and integral services as a single performance obligation. Certain deliverables and services not included in the core bundled deliverables are accounted for as separate performance obligations. The transaction price is specified in the technology licensing agreements and is substantially fixed. Some services are priced on a per-diem basis, but these are not material in the context of the contracts. Grace invoices its technology licensing customers as certain project milestones are achieved. Payment terms are similar to those of Grace’s product sales. Revenue for each performance obligation is recognized when control is transferred to the customer, which is typically over a period of time. As a result, Grace generally recognizes revenue for each performance obligation ratably over the period of the contract, which is up to eight years, depending on the scope of the licensee’s project. Based on the timing of payments, Grace records deferred revenue related to these agreements. See Note 17.
Cash Equivalents	Cash equivalents consist of liquid instruments and investments with maturities of three months or less when purchased. The recorded amounts approximate fair value.
Inventories	Inventories are stated at the lower of cost or net realizable value. The method used to determine cost is first-in/first-out, or “FIFO.” Market values for raw materials are based on current cost and, for other inventory classifications, net realizable value. Inventories are evaluated regularly for salability, and slow moving and/or obsolete items are adjusted to expected salable value. Inventory values include direct and certain indirect costs of materials and production. Abnormal costs of production are expensed as incurred.
Long Lived Assets	Properties and equipment are stated at cost. Depreciation of properties and equipment is generally computed using the straight-line method over the estimated useful life of the asset. Estimated useful lives range from 20 to 30 years for buildings, 3 to 7 years for information technology equipment, 5 to 25 years for operating machinery and equipment, and 5 to 10 years for furniture and fixtures. Interest is capitalized in connection with major project expenditures. Fully depreciated assets are retained in properties and equipment and related accumulated depreciation accounts until they are removed from service. In the case of disposals, assets and related accumulated depreciation are removed from the accounts and the net amount, less any proceeds from disposal, is charged or credited to earnings. Obligations for costs associated with asset retirements, such as requirements to restore a site to its original condition, are accrued at net present value and amortized along with the related asset.
Intangible Assets, Finite-Lived	Intangible assets with finite lives consist of technology, customer lists, trademarks, and other intangibles and are amortized over their estimated useful lives, ranging from 1 to 30 years.
Long Lived Assets, Impairment	Grace reviews long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be fully recoverable. There were no impairment charges recorded in any of the periods presented.
Goodwill	Goodwill arises from business combinations, and it is reviewed for impairment on an annual basis at October 31 and whenever events or changes in circumstances indicate that the carrying amount may not be fully recoverable. Recoverability is assessed at the reporting unit level most directly associated with the business combination that generated the goodwill. For the purpose of measuring impairment, Grace has identified its operating segments as reporting units. Grace has evaluated its goodwill annually with no impairment charge required in any of the periods presented.
Financial Instruments	Grace uses commodity forward, swap and/or option contracts; currency forward, swap, and/or option contracts; and interest rate swap contracts to manage exposure to fluctuations in commodity prices, currency exchange rates, and interest rates. Grace does not hold or issue derivative financial instruments for trading purposes. Derivative instruments are recorded at fair value in the Consolidated Balance Sheets as either assets or liabilities. For derivative instruments designated as fair value hedges, changes in the fair values of the derivative instruments closely offset changes in the fair values of the hedged items in “other (income) expense, net” in the Consolidated Statements of Operations. For derivative instruments designated as cash flow hedges, the gain or loss on the hedge is reported in “accumulated other comprehensive income (loss)” in the Consolidated Balance Sheets until it is cleared to earnings during the same period in which the hedged item affects earnings. Forward points are excluded from the assessment of effectiveness and are amortized to income on a systematic basis. For derivative instruments designated as net investment hedges, the gains and losses on the hedge, adjusted for the impact of excluded components, are recorded net of tax to “currency translation adjustments” within “accumulated other comprehensive income (loss)” to offset the change in the carrying value of the net investment being hedged. Changes in the fair value of the hedging instrument related to time value, which are excluded from the assessment of hedge effectiveness, are recorded directly to interest expense on a systematic basis. The changes in the fair values of derivative instruments that are not designated as hedges are recorded in current period earnings. Cash flows from derivative instruments are reported in the same category as the cash flows from the items being hedged.
Income Taxes	Deferred tax assets and liabilities are recognized with respect to the expected future tax consequences of events that have been recorded in the Consolidated Financial Statements. Grace reduces the carrying amounts of deferred tax assets by a valuation allowance if, based on the available evidence, it is more likely than not that such assets will not be realized. The need to establish valuation allowances for deferred tax assets is assessed quarterly. In assessing the requirement for, and amount of, a valuation allowance in accordance with the more likely than not standard, Grace gives appropriate consideration to all positive and negative evidence related to the realization of the deferred tax assets. This assessment considers, among other matters, the nature, frequency, and severity of current and cumulative losses; forecasts of future profitability; domestic and foreign source income; the duration of statutory carryforward periods; and Grace’s experience with operating loss and tax credit carryforward expirations. Tax benefits from an uncertain tax position are recognized only if it is more likely than not that the tax position will be sustained upon examination by the taxing authorities based on the technical merits of the position. Tax benefits recognized in the Consolidated Financial Statements from such a position are measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. Grace evaluates such likelihood based on relevant facts and tax law. Grace adjusts its recorded liability for income tax matters due to changes in circumstances or new uncertainties, such as amendments to existing tax law. Grace’s ultimate tax liability depends upon many factors, including negotiations with taxing authorities in the jurisdictions in which it operates, outcomes of tax litigation, and resolution of disputes arising from federal, state, and foreign tax audits. Due to the varying tax laws in each jurisdiction management, with the assistance of local tax advisors as necessary, assesses individual matters in each jurisdiction on a case-by-case basis. Grace researches and evaluates its income tax positions, including why it believes they are compliant with income tax regulations, and these positions are documented as appropriate. The U.S. Tax Cuts and Jobs Act of 2017 (“TCJA”) subjects a U.S. entity to tax on global intangible low-taxed income (“GILTI”) earned by certain foreign subsidiaries. An entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or to provide for the tax expense related to GILTI in the year the tax is incurred as a period expense only. Grace has elected to account for GILTI as a period expense in the year the tax is incurred. Grace has also adopted the tax law ordering approach for evaluating the impact of GILTI on the assessment of the realizability of US deferred tax assets.
Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block]	Grace’s method of accounting for actuarial gains and losses relating to its global defined benefit pension plans is referred to as “mark-to-market accounting.” Under mark-to-market accounting, Grace’s pension costs consist of two elements: (1) ongoing costs recognized quarterly, which include service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits; and (2) mark-to-market gains and losses recognized annually in the fourth quarter resulting from changes in actuarial assumptions, such as discount rates and the difference between actual and expected returns on plan assets. Should a significant event occur, Grace’s pension obligation and plan assets are remeasured at an interim period, and the gains or losses on remeasurement are recognized in that period.
Share-based Compensation, Option and Incentive Plans	The Company recognizes expenses related to stock-based compensation payment transactions in which it receives employee services in exchange for (a) equity instruments of the Company or (b) liabilities that are based on the fair value of the Company’s equity instruments or that may be settled by the issuance of equity instruments. Stock-based compensation cost for restricted stock units (“RSUs”) and share settled performance-based units (“PBUs”) are measured based on the high/low average of the Company’s common stock on the date of grant. Cash-settled RSUs are remeasured at the end of each reporting period based on the closing fair market value of the Company’s common stock. Stock-based compensation cost for stock options is estimated at the grant date based on each option’s fair value as calculated by the Black-Scholes option pricing model. The Company recognizes stock-based compensation cost as expense ratably on a straight-line basis over the requisite service period.
Currency Translation	Assets and liabilities of foreign subsidiaries (other than those located in countries with highly inflationary economies) are translated into U.S. dollars at current exchange rates, while revenues, costs and expenses are translated at average exchange rates during each reporting period. The resulting translation adjustments are included in “accumulated other comprehensive income (loss)” in the Consolidated Balance Sheets. The financial statements of any subsidiaries located in countries with highly inflationary economies are remeasured as if the functional currency were the U.S. dollar; the remeasurement creates translation adjustments that are reflected in net income in the Consolidated Statements of Operations.
Reclassification	Certain amounts in prior years’ Consolidated Financial Statements have been reclassified to conform to the current year presentation. Such reclassifications have not materially affected previously reported amounts in the Consolidated Financial Statements.
New Accounting Pronouncements	In December 2019, the FASB issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” This update clarifies and amends existing guidance, including removing certain exceptions to the general principles in Topic 740 and improves consistent application of and simplifies U.S. GAAP for other areas of Topic 740. Grace will adopt this update on January 1, 2021, when it becomes effective. Recently Adopted Accounting Standards In March 2020, the FASB issued ASU 2020-04 “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” This update is intended to ease the potential burden in accounting for and recognizing the effects of reference rate reform. It provides optional practical expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform, if certain criteria are met. This update became effective on March 12, 2020, and is available for use through December 31, 2022. Grace expects to utilize the practical expedients provided by this update in accounting for contract modifications and/or hedging transactions during the effective period. Grace expects the update to significantly reduce the effects of reference rate reform on the Consolidated Financial Statements. In August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20).” This update revises disclosure requirements related to defined benefit pension and other postretirement plans. Grace adopted this update in the 2020 first quarter, and it did not have a material effect on the Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13 “Financial Instruments—Credit Losses (Topic 326) Measurement of Credit Losses on Financial Instruments.” This update requires companies to implement an impairment model based on expected credit losses, rather than probable incurred losses. Grace adopted this update in the 2020 first quarter, and it did not have a material effect on the Consolidated Financial Statements.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories are stated at the lower of cost or net realizable value, and cost is determined using FIFO. Inventories consisted of the following at December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Raw materials $ 57.0 $ 64.2 In process 38.2 55.7 Finished products 126.6 154.4 Other 32.0 35.6 $ 253.8 $ 309.9

Properties and Equipment (Table

Properties and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of properties and equipment	December 31, (In millions) 2020 2019 Land $ 26.5 $ 29.5 Buildings 476.6 438.9 Information technology and equipment 124.1 131.3 Machinery, equipment and other 1,956.0 1,754.5 Projects under construction 175.7 286.6 Properties and equipment, gross 2,758.9 2,640.8 Accumulated depreciation and amortization (1,550.1) (1,497.0) Properties and equipment, net $ 1,208.8 $ 1,143.8
Lease, Cost [Table Text Block]	The following table presents Grace’s costs and cash flow information related to operating leases for the year ended December 31, 2020. Year Ended December 31, (In millions) 2020 2019 Operating lease cost $ 13.3 $ 12.1 Short-term and variable lease cost 21.1 17.9 Total lease cost $ 34.4 $ 30.0 Cash payments related to operating leases $ 13.2 $ 12.0 Right-of-use assets obtained in exchange for new operating lease liabilities 10.8 17.0 Grace’s expense for operating leases was $13.5 million in 2018. The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. December 31, Weighted average discount rate 6.2 % Weighted average remaining lease term 7.7
Schedule of minimum future payments under operating leases	The following maturity analysis presents minimum expected operating lease payments at December 31, 2020. (In millions) 2021 $ 11.8 2022 8.7 2023 5.2 2024 3.4 2025 2.2 Thereafter 15.3 Total undiscounted lease payments 46.6 Less: imputed interest 10.7 Present value of lease liabilities $ 35.9

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of carrying amount of goodwill attributable to each operating segment and the changes in those balances during the period	The carrying amount of goodwill attributable to each reportable segment and the changes in those balances during the years ended December 31, 2020 and 2019, are as follows: (In millions) Catalysts Technologies Materials Technologies Total Grace Balance, December 31, 2018 $ 496.3 $ 44.1 $ 540.4 Goodwill acquired during the year 17.8 — 17.8 Foreign currency translation (1.0) (0.3) (1.3) Balance, December 31, 2019 513.1 43.8 556.9 Foreign currency translation 4.4 1.4 5.8 Balance, December 31, 2020 $ 517.5 $ 45.2 $ 562.7
Summary of net book value of other intangible assets	Grace’s net book value of other intangible assets at December 31, 2020 and 2019, was $320.8 million and $342.8 million, respectively, detailed as follows: December 31, 2020 December 31, 2019 (In millions) Gross Carrying Accumulated Gross Carrying Accumulated Technology $ 231.6 $ 74.1 $ 232.5 $ 63.6 Customer lists 159.7 30.5 161.2 23.9 Trademarks 31.8 7.0 31.7 5.5 Other 15.7 6.4 16.1 5.7 Total $ 438.8 $ 118.0 $ 441.5 $ 98.7
Summary of estimated amortization expenses	At December 31, 2020, estimated future annual amortization expense for intangible assets is: (In millions) 2021 $ 21.8 2022 21.7 2023 21.7 2024 21.7 2025 21.7 Thereafter 212.2 $ 320.8

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Components of debt	Components of Debt December 31, (In millions) 2020 2019 2018 U.S. dollar term loan, net of unamortized debt issuance costs of $6.0 at December 31, 2020 (2019—$7.2) $ 922.6 $ 930.9 4.875% senior notes due 2027, net of unamortized debt issuance costs of $10.1 at December 31, 2020 739.9 — 5.625% senior notes due 2024, net of unamortized debt issuance costs of $1.9 at December 31, 2020 (2019—$2.4) 298.1 297.6 5.125% senior notes due 2021, net of unamortized debt issuance costs (2019—$2.7) — 697.3 Debt payable to unconsolidated affiliate 25.6 47.4 Other borrowings(1) 4.2 7.2 Total debt 1,990.4 $ 1,980.4 Less debt payable within one year 15.3 $ 23.1 Debt payable after one year $ 1,975.1 $ 1,957.3 Weighted average interest rates on total debt 3.5 % 3.8 % ___________________________________________________________________________________________________________________ (1) Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries.
Schedule of Maturities of Long-term Debt	The principal maturities of debt outstanding at December 31, 2020, were as follows: (In millions) 2021 $ 15.3 2022 14.2 2023 13.7 2024 311.4 2025 888.2 Thereafter 747.6 Total debt $ 1,990.4

Fair Value Measurements and R_2

Fair Value Measurements and Risk (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	At December 31, 2020, the carrying amounts, net of unamortized debt issuance costs and discounts (see Note 5), and fair values of Grace’s debt were as follows: December 31, 2020 December 31, 2019 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 2018 U.S. dollar term loan $ 922.6 $ 904.1 $ 930.9 $ 938.1 4.875% senior notes due 2027 739.9 784.7 — — 5.625% senior notes due 2024 298.1 322.4 297.6 329.2 5.125% senior notes due 2021 — — 697.3 727.1 Other borrowings 29.8 29.8 54.6 54.6 Total debt $ 1,990.4 $ 2,041.0 $ 1,980.4 $ 2,049.0
Schedule of assets and liabilities measured at fair value on a recurring basis	The following tables present the fair value hierarchy for financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2020 and 2019: Fair Value Measurements at December 31, 2020, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Assets Currency derivatives $ 1.6 $ — $ 1.6 $ — Total Assets $ 1.6 $ — $ 1.6 $ — Liabilities Currency derivatives $ 17.8 $ — $ 17.8 $ — Variable-to-fixed cross-currency derivatives 51.0 — 51.0 — Interest rate derivatives 5.5 — 5.5 — Total Liabilities $ 74.3 $ — $ 74.3 $ — Fair Value Measurements at December 31, 2019, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Assets Currency derivatives $ 6.1 $ — $ 6.1 $ — Variable-to-fixed cross-currency derivatives 3.4 — 3.4 — Total Assets $ 9.5 $ — $ 9.5 $ — Liabilities Currency derivatives $ 0.9 $ — $ 0.9 $ — Interest rate derivatives 3.4 — 3.4 — Total Liabilities $ 4.3 $ — $ 4.3 $ —
Schedule of the location and fair values of derivative instruments included in the Consolidated Balance Sheets	The following tables present the location and fair values of derivative instruments included in the Consolidated Balance Sheets as of December 31, 2020 and 2019: Asset Derivatives Liability Derivatives December 31, 2020 Balance Sheet Fair Balance Sheet Fair Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ — Other current liabilities $ 17.7 Currency contracts Other assets — Other liabilities 0.1 Interest rate contracts Other current assets — Other current liabilities 2.5 Interest rate contracts Other assets — Other liabilities 3.0 Variable-to-fixed cross-currency swaps Other current assets — Other current liabilities 0.2 Variable-to-fixed cross-currency swaps Other liabilities — Other liabilities 50.8 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 1.9 Other current assets — Currency contracts Other current liabilities (0.3) Other current liabilities — Total derivatives $ 1.6 $ 74.3 Asset Derivatives Liability Derivatives December 31, 2019 Balance Sheet Fair Balance Sheet Fair Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.1 Other current assets $ (3.1) Currency contracts Other assets 4.0 Other liabilities 4.0 Interest rate contracts Other current assets — Other current liabilities 1.0 Interest rate contracts Other assets — Other liabilities 2.4 Variable-to-fixed cross-currency swaps Other current assets 10.2 Other current liabilities — Variable-to-fixed cross-currency swaps Other liabilities (6.8) Other liabilities — Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets — Other current assets (0.2) Currency contracts Other current assets — Other current liabilities 0.2 Total derivatives $ 9.5 $ 4.3
Schedule of the location and amount of gains and losses on derivative instruments included in the Consolidated Statements of Operations, or initially recognized in other comprehensive income (loss) ("OCI"), when applicable	The following tables present the location and amount of gains and losses on derivative instruments included in the Consolidated Statements of Operations or, when applicable, gains and losses initially recognized in “other comprehensive income (loss)” (“OCI”) for the years ended December 31, 2020, 2019, and 2018: Year Ended December 31, 2020 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (4.0) Interest expense $ (1.8) Currency contracts(1) 1.8 Other expense 2.3 Variable-to-fixed cross-currency swaps 7.2 Interest expense 4.0 Variable-to-fixed cross-currency swaps (55.4) Other expense (55.4) Total derivatives $ (50.4) $ (50.9) Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ 4.9 ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.7) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Year Ended December 31, 2019 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (2.9) Interest expense $ (0.3) Currency contracts(1) 2.4 Other expense 1.4 Variable-to-fixed cross-currency swaps 9.1 Interest expense 13.2 Variable-to-fixed cross-currency swaps 12.5 Other expense 12.5 Total derivatives $ 21.1 $ 26.8 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (0.4) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $0.6 million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Year Ended December 31, 2018 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from Accumulated OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 0.4 Interest expense $ (0.6) Currency contracts(1) 6.3 Other expense 6.3 Variable-to-fixed cross-currency swaps (0.6) Interest expense 9.7 Variable-to-fixed cross-currency swaps 40.5 Other expense 40.5 Total derivatives $ 46.6 $ 55.9 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (4.0) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.4) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. The following table presents the total amounts of income and expense line items presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are reported. Year Ended December 31, 2020 2019 2018 (In millions) Interest expense Other income (expense) Interest expense Other income (expense) Interest expense Other income (expense) Total amounts of income and expense line items in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded $ (76.0) $ (89.0) $ (76.7) $ (80.6) $ (80.2) $ 23.2 Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Gain (loss) reclassified from accumulated OCI into income $ (1.8) $ — $ (0.3) $ — $ (0.6) $ — Variable-to-fixed cross-currency swaps Gain (loss) reclassified from accumulated OCI into income 4.0 (55.4) 13.2 12.5 9.7 40.5 Currency contracts Gain (loss) reclassified from accumulated OCI into income — 2.3 — 1.4 — 6.3 Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 1.2 — 2.8 — 3.0
Schedule of Net Investment Hedges in ACOI [Table Text Block]	The following table presents the amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges recorded to “currency translation adjustments” within “accumulated other comprehensive income (loss)” for the years ended December 31, 2020, 2019, and 2018. There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented. Year Ended December 31, (In millions) 2020 2019 2018 Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ (15.9) $ 9.1 $ 6.0 Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ — $ — $ (4.4) Foreign currency denominated deferred intercompany royalties — 0.1 0.5 $ — $ 0.1 $ (3.9)

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of income from consolidated operations before income taxes and the related provision for income taxes	The components of income from continuing operations before income taxes and the related provision for income taxes for 2020, 2019, and 2018 are as follows: (In millions) 2020 2019 2018 Income from continuing operations before income taxes: Domestic $ (76.1) $ 79.2 $ 82.2 Foreign 76.6 104.3 162.7 Total $ 0.5 $ 183.5 $ 244.9 Benefit from (provision for) income taxes: Federal—current $ (0.3) $ (6.3) $ (4.9) Federal—deferred 24.8 (19.8) (29.3) State and local—current — (0.5) 1.6 State and local—deferred (7.2) (5.8) (3.5) Foreign—current (35.1) (42.4) (49.9) Foreign—deferred 15.6 18.0 7.9 Total $ (2.2) $ (56.8) $ (78.1)
Summary of difference between the provision for income taxes at the U.S. federal income tax rate and overall income tax provision	The difference between the benefit from (provision for) income taxes on continuing operations at the U.S. federal income tax rate of 21% and Grace’s overall income tax provision is summarized as follows: (In millions) 2020 2019 2018 Tax provision at U.S. federal income tax rate $ (0.1) $ (38.5) $ (51.4) Change in benefit (provision) resulting from: GILTI high-tax exclusion amended return 25.2 — — Decrease (increase) in valuation allowance (13.5) (4.2) (6.3) Nontaxable income/non-deductible expenses (4.6) (2.5) (1.6) U.S. taxes on foreign earnings (3.9) (16.7) (30.9) State and local income taxes, net (3.4) (3.4) (1.9) Research and development credit 3.3 3.4 9.4 Unrecognized tax benefit (accruals) releases (3.1) 2.3 5.7 Effect of tax rate differential in foreign jurisdictions (2.0) (2.9) (11.3) Compensation-related adjustments (1.8) (1.7) (3.4) Provision to return adjustments (0.3) 3.0 (0.7) Benefits (charges) related to U.S. tax reform — — 17.1 Other 2.0 4.4 (2.8) Benefit from (provision for) income taxes $ (2.2) $ (56.8) $ (78.1)
Summary of tax attributes giving rise to deferred tax assets and liabilities	Deferred Tax Assets and Liabilities As of December 31, 2020 and 2019, the tax attributes giving rise to deferred tax assets and liabilities consisted of the following items. December 31, (In millions) 2020 2019 Deferred tax assets: Tax credit carryforwards $ 309.2 $ 294.7 Pension liabilities 139.2 107.7 Net operating loss carryforwards 65.2 60.3 Environmental remediation liabilities 50.3 47.0 Research and development 32.9 26.6 Unrealized currency gains and losses 30.7 12.1 Reserves and allowances 29.6 14.8 Operating lease liabilities 7.4 8.1 Compensation-related 4.0 5.4 Prepaid royalties 1.1 6.3 Other 6.8 6.9 Total deferred tax assets $ 676.4 $ 589.9 Deferred tax liabilities: Intangible assets $ (36.5) $ (27.7) Properties and equipment (20.5) (18.6) Operating lease assets (7.4) (8.0) Other (16.6) (1.4) Total deferred tax liabilities $ (81.0) $ (55.7) Valuation allowances (38.7) (24.1) Net deferred tax assets $ 556.7 $ 510.1
Summary of Operating Loss Carryforwards [Table Text Block]	The following table presents Grace’s tax effected net operating loss carryforwards and the related valuation allowances. December 31, (In millions) 2020 2019 Net operating loss carryforwards U.S. state net operating losses $ 45.4 $ 49.5 U.S. federal net operating losses 10.2 1.2 Foreign net operating losses 9.6 9.6 Net operating loss carryforwards $ 65.2 $ 60.3 Net operating loss—valuation allowances U.S. state—NOL valuation allowances $ (13.9) $ (10.1) Foreign—NOL valuation allowances (6.5) (8.0) Net operating loss—valuation allowances $ (20.4) $ (18.1)
Summary of information about uncertain tax positions	A rollforward of the balance of unrecognized tax benefits for the three years ended December 31, 2020, follows. December 31, (In millions) 2020 2019 2018 Balance at beginning of year $ 15.4 $ 14.1 $ 17.7 Increase (decrease) in positions taken in prior periods 0.2 2.6 1.2 Positions taken in the current period 3.4 2.9 0.9 Decrease due to settlements with tax authorities (0.4) (4.2) (5.7) Balance at end of year $ 18.6 $ 15.4 $ 14.1
Schedule of open tax years by major jurisdiction	Grace is subject to taxation in the U.S. and various state and foreign jurisdictions and is under continual audit by various tax authorities. As of December 31, 2020, tax years 2017 through 2019 are subject to examination by the U.S. tax authorities. In the significant non-U.S. jurisdiction, tax years 2017 through 2019 are subject to examination by the German tax authorities. Grace has tax attributes generated in prior years that are otherwise closed by statute and were carried forward into years that are open to examination. Those attributes may still be subject to adjustment to the extent utilized in open years.

Pension Plans and Other Retir_2

Pension Plans and Other Retirement Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Pension plans and other postretirement benefit plans
Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets Amounts Recognized in Balance Sheet and Assumptions Used [Table Text Block]	The following table summarizes the changes in benefit obligations and fair values of retirement plan assets during 2020 and 2019: Defined Benefit Pension Plans U.S. Non-U.S. Total (In millions) 2020 2019 2020 2019 2020 2019 Change in Projected Benefit Obligation: Benefit obligation at beginning of year $ 1,137.8 $ 1,027.1 $ 369.2 $ 305.6 $ 1,507.0 $ 1,332.7 Service cost 18.9 15.7 11.1 8.6 30.0 24.3 Interest cost 30.2 38.3 4.1 5.4 34.3 43.7 Actuarial (gain) loss—change in discount rates 106.0 144.1 52.7 58.2 158.7 202.3 Actuarial (gain) loss—other changes 8.9 (10.7) (3.7) 4.1 5.2 (6.6) Benefits paid (79.1) (76.7) (8.4) (8.4) (87.5) (85.1) Currency exchange translation adjustments — — 35.0 (4.3) 35.0 (4.3) Benefit obligation at end of year $ 1,222.7 $ 1,137.8 $ 460.0 $ 369.2 $ 1,682.7 $ 1,507.0 Change in Plan Assets: Fair value of plan assets at beginning of year $ 955.7 $ 871.1 $ 25.2 $ 19.5 $ 980.9 $ 890.6 Actual return on plan assets 115.7 154.6 2.3 4.1 118.0 158.7 Employer contributions 8.4 6.7 8.8 9.1 17.2 15.8 Benefits paid (79.1) (76.7) (8.4) (8.4) (87.5) (85.1) Currency exchange translation adjustments — — 0.8 0.9 0.8 0.9 Fair value of plan assets at end of year $ 1,000.7 $ 955.7 $ 28.7 $ 25.2 $ 1,029.4 $ 980.9 Funded status at end of year (PBO basis) $ (222.0) $ (182.1) $ (431.3) $ (344.0) $ (653.3) $ (526.1) Amounts recognized in the Consolidated Balance Sheets consist of: Noncurrent assets $ 11.4 $ 8.5 $ — $ — $ 11.4 $ 8.5 Current liabilities (7.2) (7.3) (8.5) (7.5) (15.7) (14.8) Noncurrent liabilities (226.2) (183.3) (422.8) (336.5) (649.0) (519.8) Net amount recognized $ (222.0) $ (182.1) $ (431.3) $ (344.0) $ (653.3) $ (526.1) Amounts recognized in Accumulated Other Comprehensive (Income) Loss consist of: Prior service credit $ (2.0) $ (2.6) $ (0.1) $ (0.1) $ (2.1) $ (2.7) Net amount recognized $ (2.0) $ (2.6) $ (0.1) $ (0.1) $ (2.1) $ (2.7) Defined Benefit Pension Plans U.S. Non-U.S. 2020 2019 2020 2019 Weighted Average Assumptions Used to Determine Benefit Obligations as of December 31: Discount rate 2.41 % 3.13 % 0.84 % 1.41 % Rate of compensation increase 4.50 % 4.50 % 2.58 % 2.59 % Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended December 31: Discount rate for determining service cost 3.40 % 4.46 % 1.61 % 2.42 % Discount rate for determining interest cost 2.75 % 3.86 % 1.12 % 1.84 % Expected return on plan assets 5.25 % 5.75 % 4.17 % 4.43 % Rate of compensation increase 4.50 % 4.10 % 2.59 % 2.59 %
Schedule of Net Benefit Costs [Table Text Block]	The following table presents the components of net periodic benefit cost (income) and other amounts recognized in “other comprehensive (income) loss.” (In millions) 2020 2019 2018 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Net Periodic Benefit Cost (Income) Service cost $ 18.9 $ 11.1 $ 15.7 $ 8.6 $ 19.2 $ 9.5 Interest cost 30.2 4.1 38.3 5.4 40.9 5.0 Expected return on plan assets (48.3) (1.0) (48.2) (0.9) (57.2) (1.0) Amortization of prior service cost (credit) (0.6) — (0.6) — (0.6) — Annual mark-to-market adjustment (gain) loss 47.5 47.1 26.8 59.1 (3.4) (9.2) Net curtailment and settlement gain — — — — (2.3) — Net periodic benefit cost (income) $ 47.7 $ 61.3 $ 32.0 $ 72.2 $ (3.4) $ 4.3 Other Changes in Plan Assets and Benefit Obligations Recognized in OCI Amortization of prior service cost (credit) $ 0.6 $ — $ 0.6 $ — $ 0.6 $ — Total recognized in OCI 0.6 — 0.6 — 0.6 — Total recognized in net periodic benefit cost (income) and OCI $ 48.3 $ 61.3 $ 32.6 $ 72.2 $ (2.8) $ 4.3
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Table Text Block]	The following table presents the funded status of defined benefit pension plans that are underfunded or unfunded on an accumulated benefit obligation basis. U.S. Non-U.S. Total 2020 2019 2020 2019 2020 2019 Projected benefit obligation $ 1,186.2 $ 1,102.1 $ 429.4 $ 342.1 $ 1,615.6 $ 1,444.2 Accumulated benefit obligation 1,144.2 1,058.6 384.0 306.7 1,528.2 1,365.3 Fair value of plan assets 952.8 911.6 1.3 0.8 954.1 912.4
Schedule of Expected Benefit Payments [Table Text Block]	Estimated Expected Future Benefit Payments Including Future Service for the Fiscal Years Ending Pension Plans Total U.S. Non-U.S.(1) Benefit Benefit 2021 $ 84.5 $ 9.7 $ 94.2 2022 77.5 9.4 86.9 2023 76.4 9.6 86.0 2024 76.0 10.1 86.1 2025 74.2 10.2 84.4 2026 - 2030 348.6 60.5 409.1 ___________________________________________________________________________________________________________________ (1) Non-U.S. estimated benefit payments for 2021 and future periods have been translated at the applicable December 31, 2020, exchange rates.
Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Net Funded Status	The following table presents the funded status of Grace’s pension plans: December 31, (In millions) 2020 2019 Overfunded defined benefit pension plans $ 11.4 $ 8.5 Underfunded defined benefit pension plans (128.3) (85.2) Unfunded defined benefit pension plans (520.7) (434.6) Total underfunded and unfunded defined benefit pension plans (649.0) (519.8) Pension liabilities included in other current liabilities (15.7) (14.8) Net funded status $ (653.3) $ (526.1) The tables below present the funded status of U.S. and non-U.S. pension plans. Funded Status of U.S. Pension Plans Fully-Funded U.S. Qualified Underfunded U.S. Unfunded Pay-As-You-Go (In millions) 2020 2019 2020 2019 2020 2019 Projected benefit obligation $ 36.5 $ 35.6 $ 1,076.3 $ 993.8 $ 109.9 $ 108.3 Fair value of plan assets 47.9 44.1 952.8 911.5 — — Funded status (PBO basis) $ 11.4 $ 8.5 $ (123.5) $ (82.3) $ (109.9) $ (108.3) Funded Status of Non-U.S. Pension Plans Underfunded Non-U.S. Unfunded Pay-As-You-Go (In millions) 2020 2019 2020 2019 Projected benefit obligation $ 33.5 $ 29.0 $ 426.5 $ 340.2 Fair value of plan assets 28.7 25.2 — — Funded status (PBO basis) $ (4.8) $ (3.8) $ (426.5) $ (340.2) ___________________________________________________________________________________________________________________ (1) Plans intended to be advance-funded. (2) Plans intended to be pay-as-you-go. The U.S. unfunded plans are Grace’s supplemental executive retirement plan and other supplemental executive pension arrangements, and the non-U.S. plans primarily relate to an unfunded German pension plan.
Canada | Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Allocation of Plan Assets [Table Text Block]	The target allocation of investment assets at December 31, 2020, and the actual allocation at December 31, 2020 and 2019, for the Canadian pension plan are as follows: Target Percentage of Plan Assets Canadian Pension Plan Asset Category 2020 2020 2019 Equity securities 23 % 25 % 25 % Bonds 65 % 63 % 62 % Other investments 12 % 12 % 13 % Total 100 % 100 % 100 %
Foreign Plan [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Allocation of Plan Assets [Table Text Block]	The following tables present the fair value hierarchy for the non-U.S. pension plan assets measured at fair value as of December 31, 2020 and 2019. Fair Value Measurements at December 31, 2020, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Corporate bonds $ 0.5 $ — $ 0.5 $ — Insurance contracts and other investments 0.5 — 0.5 — Cash 0.2 0.2 — — $ 1.2 $ 0.2 $ 1.0 $ — Investments measured at net asset value(1) 27.5 Total Assets at Fair Value $ 28.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Fair Value Measurements at December 31, 2019, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Corporate bonds $ 0.4 $ — $ 0.4 $ — Insurance contracts and other investments 0.5 — 0.5 — Cash 0.1 0.1 — — $ 1.0 $ 0.1 $ 0.9 $ — Investments measured at net asset value(1) 24.2 Total Assets at Fair Value $ 25.2 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.
Qualified Plan [Member] | UNITED STATES | Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Allocation of Plan Assets [Table Text Block]	The target allocation of investment assets at December 31, 2020, and the actual allocation at December 31, 2020 and 2019, for Grace’s U.S. qualified pension plans are as follows: Target Percentage of Plan Assets U.S. Qualified Pension Plans Asset Category 2020 2020 2019 Global equities 22 % 23 % 22 % Multi-asset credit 3 % 3 % 3 % Liability-hedging assets 75 % 74 % 75 % Total 100 % 100 % 100 % The following tables present the fair value hierarchy for the U.S. qualified pension plan assets measured at fair value as of December 31, 2020 and 2019. Fair Value Measurements at December 31, 2020, Using Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Common/collective trust funds $ 8.1 $ — $ 8.1 $ — Annuity and immediate participation contracts 21.1 — 21.1 — $ 29.2 $ — $ 29.2 $ — Investments measured at net asset value(1) 971.5 Total Assets at Fair Value $ 1,000.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at net asset value (“NAV”) per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets. Fair Value Measurements at December 31, 2019, Using Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Common/collective trust funds $ 8.0 $ — $ 8.0 $ — Annuity and immediate participation contracts 20.5 — 20.5 — $ 28.5 $ — $ 28.5 $ — Investments measured at net asset value(1) 927.2 Total Assets at Fair Value $ 955.7 ___________________________________________________________________________________________________________________ (1) In accordance with ASC 820-10, certain investments that are measured at NAV per share (or its equivalent) have not been classified in the fair value hierarchy. NAV is provided by the investment account manager as a practical expedient to estimate fair value. Fair values presented in the table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the Consolidated Balance Sheets.

Other Balance Sheet Accounts (T

Other Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of other balance sheet accounts	December 31, (In millions) 2020 2019 Other Current Assets Non-trade accounts receivable $ 23.1 $ 24.1 Income taxes receivable (see Note 7) 7.6 4.2 Fair value of currency, interest rate, and commodity contracts (see Note 6) 2.2 15.6 Plant under construction—unconsolidated affiliate (see Note 19) — 173.9 Other current assets 18.3 17.3 $ 51.2 $ 235.1 December 31, (In millions) 2020 2019 Other Current Liabilities Accrued compensation $ 60.6 $ 53.6 Deferred revenue (see Note 17) 33.8 35.0 Fair value of currency, interest rate, and commodity contracts (see Note 6) 21.6 2.6 Liability for dam spillway replacement (see Note 10) 20.3 4.7 Pension liabilities (see Note 8) 15.7 14.8 Environmental contingencies (see Note 10) 13.8 17.8 Operating lease liabilities (see Note 3) 10.1 9.3 Accrued interest (see Note 5) 5.8 13.3 Income taxes payable (see Note 7) 5.1 8.6 Liability to unconsolidated affiliate for plant under construction (see Note 19) — 173.9 Other accrued liabilities 95.1 86.1 $ 281.9 $ 419.7 Accrued compensation includes salaries and wages as well as estimated current amounts due under the annual and long-term incentive programs. December 31, (In millions) 2020 2019 Other Liabilities Environmental contingencies (see Note 10) $ 95.4 $ 97.5 Liability for dam spillway replacement (see Note 10) 69.3 61.7 Fair value of currency and interest rate contracts (see Note 6) 53.9 13.2 Operating lease liabilities (see Note 3) 25.8 26.2 Legacy product liability (see Note 10) 24.0 24.0 Deferred revenue (see Note 17) 23.4 29.5 Retained obligations of divested businesses 12.2 12.7 Deferred income taxes (see Note 7) 10.4 7.5 Asset retirement obligation 9.6 9.4 Unrecognized tax benefits (see Note 7) 3.9 4.1 Other noncurrent liabilities 19.7 22.4 $ 347.6 $ 308.2

Restructuring Expenses and Re_2

Restructuring Expenses and Repositioning Expenses (Tables)	12 Months Ended
	Dec. 31, 2020
Restructuring and Related Activities [Abstract]
Schedule of restructuring expenses and related asset impairments	The following table presents restructuring expenses by reportable segment for the years ended December 31, 2020, 2019, and 2018. Year Ended December 31, (In millions) 2020 2019 2018 Catalysts Technologies $ 1.8 $ 1.6 $ 13.7 Materials Technologies 0.1 1.0 0.5 Corporate — — (0.2) Total restructuring expenses $ 1.9 $ 2.6 $ 14.0
Schedule of restructuring liability	The following table presents components of the change in the restructuring liability for the years ended December 31, 2020, 2019, and 2018: (In millions) Total Balance, December 31, 2017 $ 6.7 Accruals for severance and other costs 10.1 Payments (6.1) Balance, December 31, 2018 $ 10.7 Accruals for severance and other costs 2.6 Payments (10.2) Currency translation adjustments and other 0.7 Balance, December 31, 2019 $ 3.8 Accruals for severance and other costs 3.2 Payments (3.1) Balance, December 31, 2020 $ 3.9

Other Expense, net (Tables)

Other Expense, net (Tables)	12 Months Ended
	Dec. 31, 2020
Other Income and Expenses [Abstract]
Components of other (income) expense, net	Components of other (income) expense, net are as follows: Year Ended December 31, (In millions) 2020 2019 2018 Defined benefit pension (income) expense other than service cost $ 79.5 $ 79.9 $ (27.8) Business interruption insurance recoveries (16.3) (10.7) — Hurricane-related costs 13.2 — — Net (gain) loss on sales of investments and disposals of assets 5.9 4.5 4.9 Third-party acquisition-related costs 5.2 3.6 7.3 Currency transaction effects (0.1) (0.8) (3.6) Other miscellaneous (income) expense 1.6 4.1 (4.0) Total other (income) expense, net $ 89.0 $ 80.6 $ (23.2)

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Tabular disclosure of pre-tax, tax, and after-tax components of other comprehensive income (loss)	The following tables present the pre-tax, tax, and after-tax components of Grace’s other comprehensive income (loss) for the years ended December 31, 2020, 2019, and 2018: Year Ended December 31, 2020 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (0.5) $ 0.1 $ (0.4) Currency translation adjustments (53.6) 3.7 (49.9) Gain (loss) from hedging activities 1.6 (0.8) 0.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (52.5) $ 3.0 $ (49.5) Year Ended December 31, 2019 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (0.9) $ 0.2 $ (0.7) Currency translation adjustments 18.5 (2.0) 16.5 Gain (loss) from hedging activities (7.0) 2.1 (4.9) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 10.6 $ 0.3 $ 10.9 Year Ended December 31, 2018 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Amortization of net prior service credit included in net periodic benefit cost and other costs (credits), net $ (1.2) $ 0.3 $ (0.9) Currency translation adjustments 34.6 (2.2) 32.4 Gain (loss) from hedging activities (10.0) 4.3 (5.7) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 23.4 $ 2.4 $ 25.8
Schedule of components of accumulated other comprehensive loss	The following table presents the changes in accumulated other comprehensive income (loss), net of tax, for the years ended December 31, 2020, 2019, and 2018: Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Balance, December 31, 2017 $ 0.9 $ 41.6 $ (2.6) $ 39.9 OCI before reclassifications — 32.4 11.1 43.5 Amounts reclassified from accumulated OCI (0.9) — (16.8) (17.7) Net current-period other comprehensive income (loss) (0.9) 32.4 (5.7) 25.8 Effect of adopting ASU 2018-02 0.2 2.2 (0.2) 2.2 Balance, December 31, 2018 $ 0.2 $ 76.2 $ (8.5) $ 67.9 OCI before reclassifications — 16.5 14.0 30.5 Amounts reclassified from accumulated OCI (0.7) — (18.9) (19.6) Net current-period other comprehensive income (loss) (0.7) 16.5 (4.9) 10.9 Balance, December 31, 2019 $ (0.5) $ 92.7 $ (13.4) $ 78.8 OCI before reclassifications — (49.9) (33.7) (83.6) Amounts reclassified from accumulated OCI (0.4) — 34.5 34.1 Net current-period other comprehensive income (loss) (0.4) (49.9) 0.8 (49.5) Balance, December 31, 2020 $ (0.9) $ 42.8 $ (12.6) $ 29.3

Shareholders' Equity (Deficit)

Shareholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Schedule of information relating to common stock activity	The following table sets forth information relating to common stock activity for the years ended December 31, 2020, 2019, and 2018: (In millions, except shares) Number of Shares Aggregate Proceeds Balance of outstanding shares, December 31, 2017 67,780,410 Stock options exercised 243,502 $ 6.7 Shares issued 72,590 Shares forfeited through net share exercise (132,393) Shares repurchased (1,171,141) Balance of outstanding shares, December 31, 2018 66,792,968 Stock options exercised 388,174 $ 19.1 Shares issued 94,796 Shares forfeited through net share exercise (130,256) Shares repurchased (409,769) Balance of outstanding shares, December 31, 2019 66,735,913 Stock options exercised — $ — Shares issued 128,304 Shares repurchased (673,807) Balance of outstanding shares, December 31, 2020 66,190,410

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Schedule of information relating to options	The following table sets forth information relating to such options during 2020, 2019, and 2018. Number of Average Weighted- Balance, December 31, 2017 1,813,450 $ 72.04 Options exercised (243,502) 61.92 Options forfeited (90,862) 69.82 Options terminated (33,481) 75.07 Options granted 428,190 67.36 $ 12.30 Balance, December 31, 2018 1,873,795 72.34 Options exercised (388,174) 74.33 Options forfeited (35,216) 71.21 Options terminated (74,583) 77.30 Options granted 189,787 78.11 $ 17.94 Balance, December 31, 2019 1,565,609 72.30 Options exercised — — Options forfeited (26,696) 60.26 Options terminated (473,582) 76.67 Options granted 348,005 55.34 $ 9.64 Balance, December 31, 2020 1,413,336 66.89
Schedule of summary of non-vested option activity for the period	The following is a summary of nonvested option activity for the year ended December 31, 2020. Number Of Weighted- Nonvested options outstanding at beginning of year 506,593 $ 14.81 Granted 348,005 9.64 Vested (269,148) 13.93 Forfeited (20,787) 9.90 Nonvested options outstanding at end of year 564,663 12.16
Schedule of stock options outstanding and exercisable by exercise price range	A summary of our stock options outstanding and exercisable at December 31, 2020, follows: Exercise Price Range Number Outstanding Number Exercisable Outstanding Weighted- Average Remaining Contractual Life (Years) Exercisable Weighted- Average Exercise Price $40 - $50 1,802 — 9.35 $ — $50 - $60 326,051 — 9.17 — $60 - $70 640,777 522,178 1.31 67.92 $70 - $80 444,706 326,495 3.90 72.65 1,413,336 848,673
Schedule of the assumptions used for estimating the fair value of stock options granted during the period	The following summarizes the weighted average assumptions used for estimating the fair value of stock options granted during 2020, 2019, and 2018, respectively. 2020 2019 2018 Expected volatility 22.7% - 29.4% 22.7% - 23.1% 22.9% - 24.4% Weighted average expected volatility 22.9% 23.0% 23.7% Expected term 5.5 - 6.5 years 5.5 - 6.5 years 3.0 - 6.5 years Risk-free rate 1.18% 2.58% 2.55% Dividend yield 2.2% 1.4% 1.4%
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]	Restricted Stock and Performance Based Units In 2019, the Company modified a majority of its 2017 and 2018 cash-settled LTIP awards to be stock-settled. The following is a summary of RSUs and PBUs awarded under the LTIP. 2020 2019 2018 PBUs granted under the LTIP 120,161 88,174 93,216 RSUs granted under the LTIP 68,658 57,900 86,698 Shares covered by awards forfeited under the LTIP 17,250 17,323 44,279 Weighted average grant date fair value of PBUs $55.33 $78.11 $67.39 Weighted average grant date fair value of RSUs $55.05 $76.91 $67.54 Approximate percentage of awards expected to settle in common stock(1) 96 % 96 % 94 % Approximate percentage of awards expected to settle in cash(1) 4 % 4 % 6 % ___________________________________________________________________________________________________________________ (1) Assumes full vesting.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share	The following table shows a reconciliation of the numerators and denominators used in calculating basic and diluted earnings per share. Year Ended December 31, (In millions, except per share amounts) 2020 2019 2018 Numerators Net income (loss) attributable to W. R. Grace & Co. shareholders $ (1.8) $ 126.3 $ 167.6 Denominators Weighted average common shares—basic calculation 66.3 66.8 67.2 Dilutive effect of employee stock options — 0.1 0.1 Weighted average common shares—diluted calculation 66.3 66.9 67.3 Basic earnings per share $ (0.03) $ 1.89 $ 2.49 Diluted earnings per share $ (0.03) $ 1.89 $ 2.49

Revenues Revenues (Tables)

Revenues Revenues (Tables)	12 Months Ended
	Dec. 31, 2020
Revenues [Abstract]
Disaggregation of Revenue [Table Text Block]	The following tables present Grace’s revenues by geography and product group, within its respective reportable segments, for the years ended December 31, 2020, 2019, and 2018. Year Ended December 31, 2020 North America Europe Middle East Africa (EMEA) Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 172.3 $ 231.7 $ 201.1 $ 16.5 $ 621.6 Refining Catalysts 216.6 279.1 120.4 33.7 649.8 Total Catalysts Technologies $ 388.9 $ 510.8 $ 321.5 $ 50.2 $ 1,271.4 Pharma/Consumer $ 61.5 $ 60.9 $ 19.8 $ 20.3 $ 162.5 Coatings 25.4 66.6 35.8 9.7 137.5 Chemical process 28.5 69.4 36.1 6.6 140.6 Other 4.1 13.3 0.3 0.1 17.8 Total Materials Technologies $ 119.5 $ 210.2 $ 92.0 $ 36.7 $ 458.4 Total Grace $ 508.4 $ 721.0 $ 413.5 $ 86.9 $ 1,729.8 Year Ended December 31, 2019 North America EMEA Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 191.4 $ 283.0 $ 213.7 $ 17.2 $ 705.3 Refining Catalysts 291.4 288.4 171.7 39.9 791.4 Total Catalysts Technologies $ 482.8 $ 571.4 $ 385.4 $ 57.1 $ 1,496.7 Pharma/Consumer $ 45.2 $ 59.1 $ 20.1 $ 20.2 $ 144.6 Coatings 25.9 67.8 36.9 9.2 139.8 Chemical process 38.1 79.1 32.3 6.6 156.1 Other 5.8 14.2 0.7 0.2 20.9 Total Materials Technologies $ 115.0 $ 220.2 $ 90.0 $ 36.2 $ 461.4 Total Grace $ 597.8 $ 791.6 $ 475.4 $ 93.3 $ 1,958.1 Year Ended December 31, 2018 North America EMEA Asia Pacific Latin America Total Polyolefin and Chemical Catalysts $ 192.6 $ 255.4 $ 193.2 $ 20.3 $ 661.5 Refining Catalysts 282.8 266.0 193.4 59.8 802.0 Total Catalysts Technologies $ 475.4 $ 521.4 $ 386.6 $ 80.1 $ 1,463.5 Pharma/Consumer $ 36.2 $ 58.0 $ 19.0 $ 19.4 $ 132.6 Coatings 28.1 75.3 43.3 8.7 155.4 Chemical process 35.2 81.6 32.2 8.3 157.3 Other 6.8 15.9 0.4 0.2 23.3 Total Materials Technologies $ 106.3 $ 230.8 $ 94.9 $ 36.6 $ 468.6 Total Grace $ 581.7 $ 752.2 $ 481.5 $ 116.7 $ 1,932.1
Contract with Customer, Asset and Liability [Table Text Block]	The following table presents Grace’s deferred revenue balances as of December 31, 2020 and 2019: December 31, (In millions) 2020 2019 Current $ 33.8 $ 35.0 Noncurrent 23.4 29.5 Total $ 57.2 $ 64.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block]	Grace expects to recognize revenue related to remaining performance obligations over several years, as follows: Year Approximate percentage of revenue related to remaining performance obligations recognized 2021 27 % 2022 19 % 2023 17 % 2024 16 % Thereafter through 2030 21 %

Operating Segment Information (

Operating Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of operating segment data	Reportable Segment Data Year Ended December 31, (In millions) 2020 2019 2018 Net Sales Catalysts Technologies $ 1,271.4 $ 1,496.7 $ 1,463.5 Materials Technologies 458.4 461.4 468.6 Total $ 1,729.8 $ 1,958.1 $ 1,932.1 Adjusted EBIT Catalysts Technologies segment operating income $ 309.6 $ 466.4 $ 440.9 Materials Technologies segment operating income 85.0 97.8 105.6 Corporate costs (68.0) (72.7) (73.5) Certain pension costs (14.4) (18.4) (15.9) Total $ 312.2 $ 473.1 $ 457.1 Depreciation and Amortization Catalysts Technologies $ 85.3 $ 81.9 $ 81.7 Materials Technologies 15.0 14.2 15.5 Corporate 4.7 4.2 3.6 Total $ 105.0 $ 100.3 $ 100.8 Capital Expenditures Catalysts Technologies $ 107.8 $ 114.6 $ 150.3 Materials Technologies 36.2 68.8 56.1 Corporate 13.6 10.7 9.9 Total $ 157.6 $ 194.1 $ 216.3 Total Assets Catalysts Technologies $ 2,294.9 $ 2,556.1 $ 2,326.6 Materials Technologies 448.2 430.3 375.9 Corporate 1,022.4 946.2 862.8 Total $ 3,765.5 $ 3,932.6 $ 3,565.3
Schedule of reconciliation of operating segment data to financial statements	Grace Adjusted EBIT for the years ended December 31, 2020, 2019, and 2018 is reconciled below to income (loss) before income taxes presented in the accompanying Consolidated Statements of Operations. Year Ended December 31, (In millions) 2020 2019 2018 Grace Adjusted EBIT $ 312.2 $ 473.1 $ 457.1 Pension MTM adjustment and other related costs, net (94.6) (85.9) 15.2 Loss on early extinguishment of debt (39.4) — (4.8) Costs related to legacy product, environmental and other claims (39.4) (103.5) (82.3) Restructuring and repositioning expenses (36.9) (13.7) (46.4) Inventory write-offs and disposal costs(1) (20.7) (3.6) — Third-party acquisition-related costs (5.2) (3.6) (7.3) Taxes and interest included in equity in earnings of unconsolidated affiliate (0.7) 0.1 (0.4) Benefit plan adjustment — (5.0) — Amortization of acquired inventory fair value adjustment — — (6.9) Interest expense, net (74.9) (74.8) (78.5) Net income (loss) attributable to noncontrolling interests 0.1 0.4 (0.8) Income (loss) before income taxes $ 0.5 $ 183.5 $ 244.9 ___________________________________________________________________________________________________________________ (1) Inventory write-off in 2020 related to the changes in hydroprocessing catalysts manufacturing operations (see Note 2). Inventory write-off in 2019 related to the idling of Grace’s MTO manufacturing facility.
Schedule of geographic area data	The table below presents information related to the geographic areas in which Grace operates. Sales are attributed to geographic areas based on the location to which the product is transported. Year Ended December 31, (In millions) 2020 2019 2018 Net Sales United States $ 459.8 $ 540.2 $ 533.8 Canada 48.6 57.6 47.9 Total North America 508.4 597.8 581.7 Europe Middle East Africa 721.0 791.6 752.2 Asia Pacific 413.5 475.4 481.5 Latin America 86.9 93.3 116.7 Total $ 1,729.8 $ 1,958.1 $ 1,932.1 Long-Lived Assets(1) United States $ 799.1 $ 937.9 $ 793.0 Canada 23.2 18.9 16.5 Total North America 822.3 956.8 809.5 Germany 267.4 228.2 172.5 Rest of Europe Middle East Africa 41.0 45.2 48.9 Total Europe Middle East Africa 308.4 273.4 221.4 Asia Pacific 72.2 80.3 72.9 Latin America 5.9 7.2 6.7 Total $ 1,208.8 $ 1,317.7 $ 1,110.5 ___________________________________________________________________________________________________________________ (1) Long-lived assets as of December 31, 2019 and 2018, include properties and equipment and the current asset related to a hydroprocessing catalyst plant to be transferred to ART upon completion. (See Note 19.)

Related Party Transactions Rela

Related Party Transactions Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments and Joint Ventures [Abstract]
Summary of financial information of equity method investee	The table below presents summary financial data related to ART’s balance sheet and results of operations. December 31, (In millions) 2020 2019 Summary Balance Sheet information: Current assets $ 286.4 $ 300.7 Noncurrent assets 235.8 237.8 Total assets $ 522.2 $ 538.5 Current liabilities $ 173.0 $ 177.1 Noncurrent liabilities 0.3 0.3 Total liabilities $ 173.3 $ 177.4 Year Ended December 31, (In millions) 2020 2019 2018 Summary Statement of Operations information: Net sales $ 481.9 $ 527.5 $ 487.5 Costs and expenses applicable to net sales 431.4 453.4 410.6 Income before income taxes 28.2 59.0 65.5 Net income 27.0 56.5 64.2
Summary of related party transactions - unconsolidated affiliate	The table below presents summary financial data related to transactions between Grace and ART. Year Ended December 31, (In millions) 2020 2019 2018 Product manufactured for ART $ 261.1 $ 260.8 $ 229.1 Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold 5.1 5.1 4.5 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 54.3 51.1 41.8 The table below presents balances in Grace’s Consolidated Financial Statements related to ART. December 31, (in millions) 2020 2019 Trade accounts receivable $ 28.3 $ 17.5 Other current assets — 173.9 Accounts payable 19.8 37.7 Debt payable within one year 3.5 9.9 Debt payable after one year 22.1 37.5 Other current liabilities — 173.9

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Details)	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Reportable Segments | segment	2
Revenue, Performance Obligation, Description of Payment Terms	Payment is generally due within 30 to 60 days of invoicing
Cash Equivalents
Cash Equivalents, Maximum Remaining Maturity Period at Purchase Maximum	3 months
Long-lived assets
Goodwill, Impairment Loss	$ 0	$ 0	$ 0
Tangible Asset Impairment Charges	$ 0	$ 0	$ 0
Minimum
Long-lived assets
Finite lived intangible assets, estimated useful life	1 year
Minimum | Building [Member]
Long-lived assets
Long lived assets, estimated useful life	20 years
Minimum | Information technology and equipment [Member]
Long-lived assets
Long lived assets, estimated useful life	3 years
Minimum | Operating machinery and equipment [Member]
Long-lived assets
Long lived assets, estimated useful life	5 years
Minimum | Furniture and fixtures [Member]
Long-lived assets
Long lived assets, estimated useful life	5 years
Maximum
Long-lived assets
Revenue from Contract with Customer, Contract Term	8 years
Finite lived intangible assets, estimated useful life	30 years
Maximum | Building [Member]
Long-lived assets
Long lived assets, estimated useful life	30 years
Maximum | Information technology and equipment [Member]
Long-lived assets
Long lived assets, estimated useful life	7 years
Maximum | Operating machinery and equipment [Member]
Long-lived assets
Long lived assets, estimated useful life	25 years
Maximum | Furniture and fixtures [Member]
Long-lived assets
Long lived assets, estimated useful life	10 years

Inventories (Details)

Inventories (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Inventory Disclosure [Abstract]
Raw materials	$ 57	$ 64.2
In process	38.2	55.7
Finished products	126.6	154.4
Other	32	35.6
Total inventories	$ 253.8	$ 309.9
Hydroprocessing Manufacturing Sites	3

Properties and Equipment Schedu

Properties and Equipment Schedule (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Properties and Equipment
Properties and equipment, gross	$ 2,758.9	$ 2,640.8
Accumulated depreciation and amortization	(1,550.1)	(1,497)
Properties and equipment, net	1,208.8	1,143.8
Interest Costs Capitalized	7	7.5	$ 3.2
Depreciation and amortization	105	100.3	100.8
Property, Plant and Equipment [Member]
Properties and Equipment
Depreciation and amortization	82.9	78.4	$ 80.9
Land
Properties and Equipment
Properties and equipment, gross	26.5	29.5
Building [Member]
Properties and Equipment
Properties and equipment, gross	476.6	438.9
Information technology and equipment [Member]
Properties and Equipment
Properties and equipment, gross	124.1	131.3
Machinery, equipment and other
Properties and Equipment
Properties and equipment, gross	1,956	1,754.5
Projects under construction
Properties and Equipment
Properties and equipment, gross	$ 175.7	$ 286.6

Properties and Equipment Proper

Properties and Equipment Properties and Equipment- Operating Lease Disclosures (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases- ROU Assets and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	$ 35.1	$ 34.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Current	$ 10.1	$ 9.3
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Operating Lease, Liability, Noncurrent	$ 25.8	$ 26.2
Long-lived assets
Operating Lease, Liability, Current	$ 10.1	$ 9.3
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets

Properties and Equipment Prop_2

Properties and Equipment Properties and Equipment- Lease Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases- Lease Cost [Abstract]
Operating Lease, Cost	$ 13.3	$ 12.1
Short-term and variable lease cost	21.1	17.9
Lease, Cost	34.4	30
Operating Lease, Payments	13.2	12
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 10.8	$ 17
Operating Leases, Rent Expense, Net			$ 13.5
Operating Lease, Weighted Average Discount Rate, Percent	6.20%
Operating Lease, Weighted Average Remaining Lease Term	7 years 8 months 12 days
Document Period End Date	Dec. 31, 2020

Properties and Equipment - Min.

Properties and Equipment - Min. Future Payments Leases Table (Details) $ in Millions	Dec. 31, 2020USD ($)
Property, Plant and Equipment [Abstract]
2020	$ 11.8
Lessee, Operating Lease, Liability, Payments, Due Year Two	8.7
Lessee, Operating Lease, Liability, Payments, Due Year Three	5.2
Lessee, Operating Lease, Liability, Payments, Due Year Four	3.4
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.2
Lessee, Operating Lease, Liability, Payments, Due after Year Five	15.3
Total	46.6
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	10.7
Operating Lease, Liability	35.9
Long-lived assets
Operating Lease, Liability	$ 35.9

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Changes in goodwill balances
Balance at the beginning of the period	$ 556.9	$ 540.4
Goodwill, Acquired During Period		17.8
Foreign currency translation	5.8	(1.3)
Balance at the end of the period	562.7	556.9
Grace Catalysts Technologies
Changes in goodwill balances
Balance at the beginning of the period	513.1	496.3
Goodwill, Acquired During Period		17.8
Foreign currency translation	4.4	(1)
Balance at the end of the period	517.5	513.1
Grace Materials Technologies
Changes in goodwill balances
Balance at the beginning of the period	43.8	44.1
Goodwill, Acquired During Period		0
Foreign currency translation	1.4	(0.3)
Balance at the end of the period	$ 45.2	$ 43.8

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, net book value	$ 320.8	$ 342.8
Other intangible assets
Finite-Lived Intangible Assets, Gross	438.8	441.5
Net book value of other intangible assets
Accumulated Amortization	118	98.7
Amortization of intangible assets	22.1	21.9	$ 19.9
Estimated Amortization Expenses
2019	21.8
2020	21.7
2021	21.7
2022	21.7
2023	21.7
Thereafter	212.2
Total estimated amortization expenses	320.8
Technology
Other intangible assets
Finite-Lived Intangible Assets, Gross	231.6	232.5
Net book value of other intangible assets
Accumulated Amortization	74.1	63.6
Customer Lists [Member]
Other intangible assets
Finite-Lived Intangible Assets, Gross	159.7	161.2
Net book value of other intangible assets
Accumulated Amortization	30.5	23.9
Trademarks [Member]
Other intangible assets
Finite-Lived Intangible Assets, Gross	31.8	31.7
Net book value of other intangible assets
Accumulated Amortization	7	5.5
Other Intangible Assets [Member]
Other intangible assets
Finite-Lived Intangible Assets, Gross	15.7	16.1
Net book value of other intangible assets
Accumulated Amortization	$ 6.4	$ 5.7

Debt - Components Table (Detail

Debt - Components Table (Details) - USD ($)	Jul. 13, 2020	Jun. 26, 2020	Apr. 03, 2018	Sep. 16, 2014	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt Instrument, Price as Percent of Par Value				100.00%
Loss on early extinguishment of debt					$ 39,400,000	$ 39,400,000	$ 0	$ 4,800,000
Defined Benefit Plan, Plan Assets, Contributions by Employer								50,000,000
Interest Paid, Excluding Capitalized Interest, Operating Activities						74,200,000	67,700,000	$ 75,200,000
Debt, Long-term and Short-term, Combined Amount						1,990,400,000	1,980,400,000
Debt payable within one year						15,300,000	23,100,000
Notes Payable, Related Parties						25,600,000	47,400,000
Debt payable after one year						$ 1,975,100,000	$ 1,957,300,000
Debt, Weighted Average Interest Rate						3.50%	3.80%
Document Period End Date						Dec. 31, 2020
Senior Notes, Due 2024 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.625%		5.625%	5.625%
Debt Instrument, Face Amount				$ 300,000,000
Debt, Long-term and Short-term, Combined Amount						$ 298,100,000	$ 297,600,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 1,900,000	$ 2,400,000
Senior Notes, Due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.125%		5.125%	5.125%
Debt Instrument, Face Amount				$ 700,000,000
Interest Paid, Excluding Capitalized Interest, Operating Activities	$ 10,100,000
Cash Paid Redemption of Debt Including Premium and Interest	748,000,000
Redemption Premium	37,900,000
Extinguishment of Debt, Amount	$ 700,000,000
Debt, Long-term and Short-term, Combined Amount						$ 0	$ 697,300,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net							2,700,000
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Event of Default, Percent Principal Aggregate Outstanding				25.00%
Final Judgment for Payment, Event of Debt Default				$ 75,000,000
Debt Instrument, Required Redemption Price, Percentage				101.00%
Debt Instrument, Redemption Price, Percentage				100.00%
Senior Notes				$ 1,000,000,000
Debt Instrument, Covenant Description				The Notes were issued subject to covenants that limit the Issuer’s and certain of its subsidiaries’ ability, subject to certain exceptions and qualifications, to (i) create or incur liens on assets, (ii) enter into any sale and leaseback transaction and (iii) in the case of the Issuer, merge or consolidate with another company. Grace is in compliance with these covenants.
Debt Instrument Default Terms				The Notes were also issued subject to customary events of default which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for the payment of $75 million or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the trustee or the holders of at least 25% in aggregate principal amount of the then outstanding series of Notes may declare all the Notes of such series to be due and payable immediately
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			175.00%
Debt Instrument, Face Amount			$ 400,000,000
2025 Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment			$ 9,500,000
Debt Instrument, Basis Spread on Variable Rate			175.00%
Debt Instrument, Face Amount			$ 950,000,000
Debt, Long-term and Short-term, Combined Amount						922,600,000	930,900,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 6,000,000	$ 7,200,000
Senior Notes, Due 2027
Debt Instrument [Line Items]
Debt Instrument, Required Redemption Price, Percentage		101.00%
Debt Instrument, Redemption Price, Percentage		100.00%
Proceeds from Debt, Net of Issuance Costs		$ 741,600,000
Debt Instrument, Price as Percent of Par Value		100.00%
Debt Instrument, Interest Rate, Stated Percentage		4.875%				4.875%	4.875%
Debt Instrument, Face Amount		$ 750,000,000
Debt Instrument, Covenant Description		The Senior Notes due 2027 were issued subject to covenants that limit the ability of the Company, the Issuer, and certain of the Company’s subsidiaries to: (i) incur liens on assets; (ii) enter into sale and leaseback transactions larger than the greater of $100 million or 2.5% of total assets; and (iii) merge or consolidate with another company; subject to certain exceptions and qualifications.
Debt Instrument Default Terms		The Senior Notes due 2027 were issued subject to customary events of default, which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for payment of the greater of (i) $100 million and (ii) 2.5% of Total Assets (as defined in the Indenture) or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the Trustee or the holders of at least 30% in aggregate principal amount of the then outstanding series of Senior Notes due 2027 may declare all the Senior Notes due 2027 of such series to be due and payable immediately.
Debt, Long-term and Short-term, Combined Amount						$ 739,900,000	$ 0
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						10,100,000
2018 Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Description			The Credit Agreement contains customary affirmative covenants, including, but not limited to: (i) maintenance of existence, and compliance with laws; (ii) delivery of consolidated financial statements and other information; (iii) payment of taxes; (iv) delivery of notices of defaults and certain other material events; and (v) maintenance of adequate insurance. The Credit Agreement also contains customary negative covenants, including but not limited to restrictions on: (i) dividends on, and redemptions of, equity interests and other restricted payments; (ii) liens; (iii) loans and investments; (iv) the sale, transfer or disposition of assets and businesses; (v) transactions with affiliates; and (vi) a maximum first lien leverage ratio.
Debt Instrument Default Terms			Events of default under the Credit Agreement include, but are not limited to: (i) failure to pay principal, interest, fees or other amounts under the Credit Agreement when due, taking into account any applicable grace period; (ii) any representation or warranty proving to have been incorrect in any material respect when made; (iii) failure to perform or observe covenants or other terms of the Credit Agreement subject to certain grace periods; (iv) a cross-default and cross-acceleration with certain other material debt; (v) bankruptcy events; (vi) certain defaults under ERISA; and (vii) the invalidity or impairment of security interests.
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity						391,800,000
Long-term Line of Credit						0
Other borrowings [Member]
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount						$ 4,200,000	$ 7,200,000

Debt Narrative (Details)

Debt Narrative (Details) - USD ($) $ in Millions	Jul. 13, 2020	Jun. 26, 2020	Apr. 03, 2018	Sep. 16, 2014	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Loss on early extinguishment of debt					$ 39.4	$ 39.4	$ 0	$ 4.8
Interest Paid, Excluding Capitalized Interest, Operating Activities						$ 74.2	$ 67.7	$ 75.2
Debt Instrument, Price as Percent of Par Value				100.00%
Senior Notes, Due 2027
Debt Instrument [Line Items]
Debt Instrument Default Terms		The Senior Notes due 2027 were issued subject to customary events of default, which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for payment of the greater of (i) $100 million and (ii) 2.5% of Total Assets (as defined in the Indenture) or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the Trustee or the holders of at least 30% in aggregate principal amount of the then outstanding series of Senior Notes due 2027 may declare all the Senior Notes due 2027 of such series to be due and payable immediately.
Debt Instrument, Covenant Description		The Senior Notes due 2027 were issued subject to covenants that limit the ability of the Company, the Issuer, and certain of the Company’s subsidiaries to: (i) incur liens on assets; (ii) enter into sale and leaseback transactions larger than the greater of $100 million or 2.5% of total assets; and (iii) merge or consolidate with another company; subject to certain exceptions and qualifications.
Debt Instrument, Required Redemption Price, Percentage		101.00%
Debt Instrument, Redemption Price, Percentage		100.00%
Debt Instrument, Price as Percent of Par Value		100.00%
Proceeds from Debt, Net of Issuance Costs		$ 741.6
Debt Instrument, Interest Rate, Stated Percentage		4.875%				4.875%	4.875%
Debt Instrument, Face Amount		$ 750
Senior Notes, Due 2021 [Member]
Debt Instrument [Line Items]
Redemption Premium	$ 37.9
Interest Paid, Excluding Capitalized Interest, Operating Activities	10.1
Cash Paid Redemption of Debt Including Premium and Interest	748
Extinguishment of Debt, Amount	$ 700
Debt Instrument, Interest Rate, Stated Percentage				5.125%		5.125%	5.125%
Debt Instrument, Face Amount				$ 700
2025 Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment			$ 9.5
Debt Instrument, Basis Spread on Variable Rate			175.00%
Debt Instrument, Face Amount			$ 950
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			175.00%
Debt Instrument, Face Amount			$ 400
2018 Credit Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument Default Terms			Events of default under the Credit Agreement include, but are not limited to: (i) failure to pay principal, interest, fees or other amounts under the Credit Agreement when due, taking into account any applicable grace period; (ii) any representation or warranty proving to have been incorrect in any material respect when made; (iii) failure to perform or observe covenants or other terms of the Credit Agreement subject to certain grace periods; (iv) a cross-default and cross-acceleration with certain other material debt; (v) bankruptcy events; (vi) certain defaults under ERISA; and (vii) the invalidity or impairment of security interests.
Debt Instrument, Covenant Description			The Credit Agreement contains customary affirmative covenants, including, but not limited to: (i) maintenance of existence, and compliance with laws; (ii) delivery of consolidated financial statements and other information; (iii) payment of taxes; (iv) delivery of notices of defaults and certain other material events; and (v) maintenance of adequate insurance. The Credit Agreement also contains customary negative covenants, including but not limited to restrictions on: (i) dividends on, and redemptions of, equity interests and other restricted payments; (ii) liens; (iii) loans and investments; (iv) the sale, transfer or disposition of assets and businesses; (v) transactions with affiliates; and (vi) a maximum first lien leverage ratio.
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Default Terms				The Notes were also issued subject to customary events of default which include (subject in certain cases to customary grace and cure periods), among others, nonpayment of principal or interest; breach of other agreements in the Indenture; failure to pay certain other indebtedness; failure to discharge a final judgment for the payment of $75 million or more (excluding any amounts covered by insurance or indemnities) rendered against the Issuer or any of its significant subsidiaries; and certain events of bankruptcy or insolvency. Generally, if any event of default occurs, the trustee or the holders of at least 25% in aggregate principal amount of the then outstanding series of Notes may declare all the Notes of such series to be due and payable immediately
Debt Instrument, Covenant Description				The Notes were issued subject to covenants that limit the Issuer’s and certain of its subsidiaries’ ability, subject to certain exceptions and qualifications, to (i) create or incur liens on assets, (ii) enter into any sale and leaseback transaction and (iii) in the case of the Issuer, merge or consolidate with another company. Grace is in compliance with these covenants.
Debt Instrument, Required Redemption Price, Percentage				101.00%
Debt Instrument, Redemption Price, Percentage				100.00%
Debt Instrument, Event of Default, Percent Principal Aggregate Outstanding				25.00%
Debt Instrument, Redemption Basis Spread On Variable Rate				50.00%
Final Judgment for Payment, Event of Debt Default				$ 75

Debt Debt- Maturity Schedule (D

Debt Debt- Maturity Schedule (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 15.3
2021	14.2
2022	13.7
2023	311.4
2024	888.2
Thereafter	747.6
Debt, Long-term and Short-term, Combined Amount	$ 1,990.4	$ 1,980.4

Fair Value Measurements and R_3

Fair Value Measurements and Risk Fair Value Measurements and Risk - Narrative (Details) € in Millions	12 Months Ended
	Dec. 31, 2020USD ($)country	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2020EUR (€)country	Nov. 05, 2018USD ($)	Nov. 05, 2018EUR (€)	Apr. 03, 2018USD ($)	Apr. 03, 2018EUR (€)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maximum Remaining Maturity of Foreign Currency Derivatives	36 months
Number of Countries in which Entity Operates | country	60			60
Number of Currencies Used	30			30
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Amount of Hedged Item							$ 100,000,000
Derivative, Fixed Interest Rate							2.775%	2.775%
Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Notional Amount	$ 419,200,000
2018 Credit Agreement [Member] | Cross Currency Interest Rate Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Amount of Hedged Item					$ 600,000,000		$ 600,000,000
Derivative, Notional Amount | €						€ 525.9		€ 490.1
Derivative, Cash Received on Hedge		$ 33,100,000
Derivative, Fixed Interest Rate					1.785%	1.785%	2.0231%	2.0231%
Net Investment Hedging [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	$ 0
Net Investment Hedging [Member] | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Excluded Component, Gain (Loss), Recognized in Earnings	$ 3,000,000	$ 3,300,000	$ 2,300,000
Derivative, Notional Amount | €				€ 170

Fair Value Measurements and R_4

Fair Value Measurements and Risk - Carrying Amounts and Fair Values of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jun. 26, 2020	Dec. 31, 2019	Sep. 16, 2014
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 1,990.4		$ 1,980.4
Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	2,041		2,049
Debt, Long-term and Short-term, Combined Amount	1,990.4		1,980.4
2018 Credit Agreement [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	922.6		930.9
2018 Credit Agreement [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	904.1		938.1
Senior Notes, Due 2021 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	0		697.3
Senior Notes, Due 2021 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	0		727.1
Senior Notes, Due 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 0		697.3
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net			$ 2.7
Debt Instrument, Interest Rate, Stated Percentage	5.125%		5.125%	5.125%
Senior Notes, Due 2024 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 298.1		$ 297.6
Senior Notes, Due 2024 [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	322.4		329.2
Senior Notes, Due 2024 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	298.1		297.6
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ 1.9		$ 2.4
Debt Instrument, Interest Rate, Stated Percentage	5.625%		5.625%	5.625%
Senior Notes, Due 2027 | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 739.9		$ 0
Senior Notes, Due 2027 | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	784.7		0
Senior Notes, Due 2027
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	739.9		$ 0
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ 10.1
Debt Instrument, Interest Rate, Stated Percentage	4.875%	4.875%	4.875%
Other borrowings [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 29.8		$ 54.6
Other borrowings [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	29.8		54.6
Other borrowings [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$ 4.2		$ 7.2

Fair Value Measurements and R_5

Fair Value Measurements and Risk - Financial Assets and Liabilities (Details 2) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 1.6	$ 9.5
Derivative Liability, Fair Value, Gross Liability	74.3	4.3
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	1.6	9.5
Derivative Liability, Fair Value, Gross Liability	74.3	4.3
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	1.6	9.5
Derivative Liability, Fair Value, Gross Liability	74.3	4.3
Foreign Exchange Contract [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	1.6	6.1
Derivative Liability, Fair Value, Gross Liability	17.8	0.9
Foreign Exchange Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset	1.6	6.1
Derivative Liability, Fair Value, Gross Liability	17.8	0.9
Cross Currency Interest Rate Contract [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		3.4
Derivative Liability, Fair Value, Gross Liability	51
Cross Currency Interest Rate Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Fair Value, Gross Asset		3.4
Derivative Liability, Fair Value, Gross Liability	51
Interest Rate Contract [Member] | Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Gross Liability	5.5	3.4
Interest Rate Contract [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 5.5	$ 3.4

Fair Value Measurements and R_6

Fair Value Measurements and Risk Fair Value Measurements and Risk - Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 1.6	$ 9.5
Derivative Liability, Fair Value, Gross Liability	74.3	4.3
Foreign Exchange Contract [Member] | Other Current Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	2.1
Derivative Liability, Fair Value, Gross Liability		(3.1)
Foreign Exchange Contract [Member] | Other Current Assets [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1.9	0
Derivative Liability, Fair Value, Gross Liability	0	(0.2)
Foreign Exchange Contract [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	4
Foreign Exchange Contract [Member] | Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	17.7
Foreign Exchange Contract [Member] | Other Current Liabilities [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	(0.3)
Derivative Liability, Fair Value, Gross Liability	0	0.2
Foreign Exchange Contract [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.1	4
Interest Rate Contract [Member] | Other Current Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Interest Rate Contract [Member] | Other Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Interest Rate Contract [Member] | Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	2.5	1
Interest Rate Contract [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	3	2.4
Cross Currency Interest Rate Contract [Member] | Other Current Assets [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	10.2
Cross Currency Interest Rate Contract [Member] | Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0.2	0
Cross Currency Interest Rate Contract [Member] | Other Liabilities [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	(6.8)
Derivative Liability, Fair Value, Gross Liability	$ 50.8	$ 0

Fair Value Measurements and R_7

Fair Value Measurements and Risk - Gain (Loss) on Derivative Instruments (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gains and losses on derivative instruments
Interest and Debt Expense	$ (76)	$ (76.7)	$ (80.2)
Nonoperating Income (Expense)	(89)	(80.6)	23.2
Derivatives in ASC 815 cash flow hedging relationships
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	(50.4)	21.1	46.6
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(50.9)	26.8	55.9
Derivatives in ASC 815 cash flow hedging relationships | Interest Rate Contract [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	(4)	(2.9)	0.4
Derivatives in ASC 815 cash flow hedging relationships | Interest Rate Contract [Member] | Interest Expense [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(1.8)	(0.3)	(0.6)
Derivatives in ASC 815 cash flow hedging relationships | Cross Currency Interest Rate Contract [Member] | Interest Expense [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	7.2	9.1	(0.6)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	4	13.2	9.7
Derivatives in ASC 815 cash flow hedging relationships | Cross Currency Interest Rate Contract [Member] | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	(55.4)	12.5	40.5
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	(55.4)	12.5	40.5
Derivatives in ASC 815 cash flow hedging relationships | Currency contracts
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	1.8	2.4	6.3
Derivatives in ASC 815 cash flow hedging relationships | Currency contracts | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax	2.3	1.4	6.3
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	1.2	2.8	3
Not Designated as Hedging Instrument [Member] | Currency contracts | Nonoperating Income (Expense) [Member]
Gains and losses on derivative instruments
Derivative Instruments, Gain (Loss) Recognized in Income, Net	4.9	(0.4)	(4)
AOCI, Derivative Qualifying as Hedge, Excluded Component, Parent [Member] | Derivatives in ASC 815 cash flow hedging relationships | Currency contracts
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax	$ (0.7)	$ 0.6	$ (0.4)

Fair Value Measurements and R_8

Fair Value Measurements and Risk Fair Value Measurement and Risk - Gain (Loss) on Derivatives and Non-derivatives Designated as Net Investment Hedges (Details 4) - Net Investment Hedging [Member] - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	$ 0	$ 100,000	$ (3,900,000)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0	0
Currency Swap [Member]
Gains and losses on derivative instruments
Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), before Reclassification and Tax	(15,900,000)	9,100,000	6,000,000
Foreign currency denominated debt [Member]
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	0	0	(4,400,000)
Foreign currency denominated deferred intercompany royalties [Member]
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	$ 0	$ 100,000	$ 500,000

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Deferred Tax Assets, Research and Development	$ 32.9	$ 26.6
Income before income taxes:
Domestic	(76.1)	79.2	$ 82.2
Foreign	76.6	104.3	162.7
Income (loss) before income taxes	0.5	183.5	244.9
Provision for income taxes:
Federal-current	(0.3)	(6.3)	(4.9)
Federal-deferred	24.8	(19.8)	(29.3)
State and local-current	0	(0.5)	1.6
State and local - deferred	(7.2)	(5.8)	(3.5)
Foreign-current	(35.1)	(42.4)	(49.9)
Foreign-deferred	15.6	18	7.9
(Provision for) benefit from income taxes	$ (2.2)	(56.8)	(78.1)
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Income tax provision analysis
Tax provision at U.S. federal income tax rate	$ (0.1)	(38.5)	(51.4)
Effective Income Tax Rate Reconciliation, Tax Reform, Amount	0	0	(17.1)
Change in provision resulting from:
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	25.2	0	0
Decrease (increase) in valuation allowance	(13.5)	(4.2)	(6.3)
Nontaxable income/non-deductible expenses	(4.6)	(2.5)	(1.6)
Effective Income Tax Rate Reconciliation, U.S. taxes on foreign earnings	(3.9)	(16.7)	(30.9)
State and local income taxes, net	(3.4)	(3.4)	(1.9)
Research and development credit	3.3	3.4	9.4
Effective Income Tax Rate Reconciliation, Unrecognized tax benefit accrual/releases	(3.1)	2.3	5.7
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	(2)	(2.9)	(11.3)
Stock-based compensation	(1.8)	(1.7)	(3.4)
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount	(0.3)	3	(0.7)
Effective Income Tax Rate Reconciliation, Tax Reform, Amount	0	0	17.1
Other	2	4.4	(2.8)
(Provision for) benefit from income taxes	$ (2.2)	$ (56.8)	$ (78.1)

Income Taxes Income Taxes- Attr

Income Taxes Income Taxes- Attributes Giving Rise to Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets and Liabilities [Line Items]
Tax credit carryforwards	$ 309.2	$ 294.7
Pension liabilities	139.2	107.7
Deferred Tax Assets, Operating Loss Carryforwards	65.2	60.3
Liability for environmental remediation	50.3	47
Reserves and allowances	29.6	14.8
Deferred Tax Assets, Unrealized Currency Losses	30.7	12.1
Deferred Tax Assets Operating Lease Liabilities	7.4	8.1
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits	4	5.4
Prepaid royalties	1.1	6.3
Other	6.8	6.9
Total deferred tax assets	676.4	589.9
Intangible assets	(36.5)	(27.7)
Properties and equipment	(20.5)	(18.6)
Deferred Tax Liabilities, Leasing Arrangements	(7.4)	(8)
Other	(16.6)	(1.4)
Deferred Tax Liabilities, Gross	(81)	(55.7)
Deferred Tax Assets, Valuation Allowance	(38.7)	(24.1)
Net deferred tax assets	556.7	$ 510.1
Domestic Tax Authority [Member]
Deferred Tax Assets and Liabilities [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 11.5

Income Taxes- NOL Carryforwards

Income Taxes- NOL Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	$ 317.4
Deferred Tax Assets, Operating Loss Carryforwards, Federal, Gross of UTB	13.1
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	47.4
Deferred Tax Assets, State Taxes	1.6
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	45.4	$ 49.5
U.S. net operating loss carryforwards	10.2	1.2
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	9.6	9.6
Deferred Tax Assets, Operating Loss Carryforwards	65.2	60.3
Operating Loss Carryforwards, Valuation Allowance	(20.4)	(18.1)
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Valuation Allowance	(6.5)	(8)
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards, Valuation Allowance	(13.9)	$ (10.1)
Tax Credit Carryforward [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	1,600
Net Operating Loss and Tax Credits | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	$ 3,100

Income Taxes Income Taxes - Unr

Income Taxes Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 18.6	$ 15.4	$ 14.1	$ 17.7
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	0.2	2.6	1.2
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	3.4	2.9	0.9
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	(0.4)	$ (4.2)	$ (5.7)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0.2
Deferred Tax Assets, Tax Credit Carryforwards, Gross of UTB	317.4
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	$ 47.4

Income Taxes - Tax Examinations

Income Taxes - Tax Examinations (Details)	12 Months Ended
	Dec. 31, 2020
Germany
Income Tax Examination [Line Items]
Open Tax Year	2017 2018 2019
Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Open Tax Year	2017 2018 2019

Pension Plans and Other Retir_3

Pension Plans and Other Retirement Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	$ 11.4	$ 8.5
Unfunded defined benefit pension plans	(649)	(519.8)
Pension liabilities included in other current liabilities	(15.7)	(14.8)
Net funded status	(653.3)	(526.1)
Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	11.4	8.5
Net funded status	(653.3)	(526.1)
Defined Benefit Plan, Benefit Obligation	1,682.7	1,507	$ 1,332.7
Enhanced Defined Contribution Plans [Member]
Pension Plans
Defined Contribution Plan, Cost	3.5	2.9	1.7
Underfunded Plan [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Unfunded defined benefit pension plans	(128.3)	(85.2)
Unfunded Plan [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Unfunded defined benefit pension plans	(520.7)	(434.6)
Foreign Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	0	0
Net funded status	(431.3)	(344)
Defined Benefit Plan, Benefit Obligation	$ 460	$ 369.2	305.6
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	0.84%	1.41%
Foreign Plan [Member] | Underfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	$ (4.8)	$ (3.8)
Defined Benefit Plan, Benefit Obligation	33.5	29
Foreign Plan [Member] | Unfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	(426.5)	(340.2)
Defined Benefit Plan, Benefit Obligation	$ 426.5	340.2
UNITED STATES
Pension Plans
Percentage that the employer contributes of employee contributions under 401(k) plan	100.00%
Funded status of fully funded, underfunded, and unfunded pension plans:
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	6.00%
UNITED STATES | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	$ 11.4	8.5
Net funded status	(222)	(182.1)
Defined Benefit Plan, Benefit Obligation	$ 1,222.7	$ 1,137.8	1,027.1
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.41%	3.13%
UNITED STATES | Enhanced Defined Contribution Plans [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Defined Contribution Plan, Employer Contribution, Percent	4.00%
UNITED STATES | Standard Defined Contribution Plan
Pension Plans
Defined Contribution Plan, Cost	$ 14.3	$ 13.9	$ 12.6
UNITED STATES | Underfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	(123.5)	(82.3)
Defined Benefit Plan, Benefit Obligation	1,076.3	993.8
UNITED STATES | Unfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	(109.9)	(108.3)
Defined Benefit Plan, Benefit Obligation	109.9	108.3
UNITED STATES | Overfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	11.4	8.5
Defined Benefit Plan, Benefit Obligation	$ 36.5	$ 35.6

Pension Plans and Other Retir_4

Pension Plans and Other Retirement Plans (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in Plan Assets:
Net funded status	$ (653.3)	$ (526.1)
Amounts recognized in the Consolidated Balance Sheets consist of:
Noncurrent assets	11.4	8.5
Net Periodic Benefit Cost
Annual mark-to-market adjustment (gain) loss	94.6	85.9	$ (15.2)
Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	1,507	1,332.7
Service cost	30	24.3
Interest cost	34.3	43.7
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss), Change in Rates	158.7	202.3
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) - Other	5.2	(6.6)
Benefits paid	(87.5)	(85.1)
Currency exchange translation adjustments	35	(4.3)
Benefit obligation at end of year	1,682.7	1,507	1,332.7
Change in Plan Assets:
Fair value of plan assets at beginning of year	980.9	890.6
Actual return on plan assets	118	158.7
Employer contributions	17.2	15.8
Benefits paid	(87.5)	(85.1)
Currency exchange translation adjustments	0.8	0.9
Fair value of plan assets at end of year	1,029.4	980.9	890.6
Net funded status	(653.3)	(526.1)
Amounts recognized in the Consolidated Balance Sheets consist of:
Noncurrent assets	11.4	8.5
Current liabilities	(15.7)	(14.8)
Noncurrent liabilities	(649)	(519.8)
Net amount recognized	(653.3)	(526.1)
Amounts recognized in Accumulated Other Comprehensive Loss consist of:
Prior service cost (credit)	(2.1)	(2.7)
Net amount recognized	(2.1)	(2.7)
Net Periodic Benefit Cost
Service cost	30	24.3
Interest cost	34.3	43.7
Enhanced Defined Contribution Plans [Member]
Pension plans and other postretirement benefit plans
Defined Contribution Plan, Cost	3.5	2.9	1.7
UNITED STATES | Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	1,137.8	1,027.1
Service cost	18.9	15.7	19.2
Interest cost	30.2	38.3	40.9
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss), Change in Rates	106	144.1
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) - Other	8.9	(10.7)
Benefits paid	(79.1)	(76.7)
Benefit obligation at end of year	1,222.7	1,137.8	1,027.1
Change in Plan Assets:
Fair value of plan assets at beginning of year	955.7	871.1
Actual return on plan assets	115.7	154.6
Employer contributions	8.4	6.7
Benefits paid	(79.1)	(76.7)
Fair value of plan assets at end of year	1,000.7	955.7	871.1
Net funded status	(222)	(182.1)
Amounts recognized in the Consolidated Balance Sheets consist of:
Noncurrent assets	11.4	8.5
Current liabilities	(7.2)	(7.3)
Noncurrent liabilities	(226.2)	(183.3)
Net amount recognized	(222)	(182.1)
Amounts recognized in Accumulated Other Comprehensive Loss consist of:
Prior service cost (credit)	(2)	(2.6)
Net amount recognized	$ (2)	$ (2.6)
Weighted Average Assumptions Used to Determine Benefit Obligations as of the period
Discount rate	2.41%	3.13%
Rate of compensation increase	4.50%	4.50%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Service Cost	3.40%	4.46%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Interest Cost	2.75%	3.86%
Expected return on plan assets	5.25%	5.75%
Rate of compensation increase	4.50%	4.10%
Net Periodic Benefit Cost
Service cost	$ 18.9	$ 15.7	19.2
Interest cost	30.2	38.3	40.9
Expected return on plan assets	(48.3)	(48.2)	(57.2)
Amortization of prior service cost (credit)	(0.6)	(0.6)	(0.6)
Annual mark-to-market adjustment (gain) loss	47.5	26.8	(3.4)
Net curtailment and settlement gain	0	0	(2.3)
Net periodic benefit cost	47.7	32	(3.4)
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Amortization of prior service cost (credit)	0.6	0.6	0.6
Total recognized in other comprehensive (income) loss	0.6	0.6	0.6
Total recognized in net periodic benefit cost and other comprehensive (income) loss	48.3	32.6	(2.8)
Foreign Plan [Member] | Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	369.2	305.6
Service cost	11.1	8.6	9.5
Interest cost	4.1	5.4	5
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss), Change in Rates	52.7	58.2
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) - Other	(3.7)	4.1
Benefits paid	(8.4)	(8.4)
Currency exchange translation adjustments	35	(4.3)
Benefit obligation at end of year	460	369.2	305.6
Change in Plan Assets:
Fair value of plan assets at beginning of year	25.2	19.5
Actual return on plan assets	2.3	4.1
Employer contributions	8.8	9.1
Benefits paid	(8.4)	(8.4)
Currency exchange translation adjustments	0.8	0.9
Fair value of plan assets at end of year	28.7	25.2	19.5
Net funded status	(431.3)	(344)
Amounts recognized in the Consolidated Balance Sheets consist of:
Noncurrent assets	0	0
Current liabilities	(8.5)	(7.5)
Noncurrent liabilities	(422.8)	(336.5)
Net amount recognized	(431.3)	(344)
Amounts recognized in Accumulated Other Comprehensive Loss consist of:
Prior service cost (credit)	(0.1)	(0.1)
Net amount recognized	$ (0.1)	$ (0.1)
Weighted Average Assumptions Used to Determine Benefit Obligations as of the period
Discount rate	0.84%	1.41%
Rate of compensation increase	2.58%	2.59%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Service Cost	1.61%	2.42%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate, Interest Cost	1.12%	1.84%
Expected return on plan assets	4.17%	4.43%
Rate of compensation increase	2.59%	2.59%
Net Periodic Benefit Cost
Service cost	$ 11.1	$ 8.6	9.5
Interest cost	4.1	5.4	5
Expected return on plan assets	(1)	(0.9)	(1)
Amortization of prior service cost (credit)	0	0	0
Annual mark-to-market adjustment (gain) loss	47.1	59.1	(9.2)
Net curtailment and settlement gain	0	0	0
Net periodic benefit cost	61.3	72.2	4.3
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Amortization of prior service cost (credit)	0	0	0
Total recognized in other comprehensive (income) loss	0	0	0
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ 61.3	$ 72.2	$ 4.3
Canada | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan Percentage of Certain Specified foreign Plan Assets to Total Foreign Plan Assets	95.00%	96.00%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Expected return on plan assets	4.25%
Other Foreign Member [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan Percentage of Certain Specified foreign Plan Assets to Total Foreign Plan Assets	5.00%	4.00%

Pension Plans and Other Retir_5

Pension Plans and Other Retirement Plans (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Funded Status of Pension Plans
Net funded status	$ (653.3)	$ (526.1)
Pension Plans
Funded Status of Pension Plans
Projected benefit obligation	1,682.7	1,507	$ 1,332.7
Defined Benefit Plan, Plan Assets, Amount	1,029.4	980.9	890.6
Net funded status	(653.3)	(526.1)
Defined Benefit Plan, Accumulated Benefit Obligation	1,590	1,423
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation	1,615.6	1,444.2
Accumulated benefit obligation	1,528.2	1,365.3
Fair value of plan assets	954.1	$ 912.4
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	94.2
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	86.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	86
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	86.1
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	84.4
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 409.1
Pension Plans | UNITED STATES
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100.00%	100.00%
Funded Status of Pension Plans
Projected benefit obligation	$ 1,222.7	$ 1,137.8	1,027.1
Defined Benefit Plan, Plan Assets, Amount	1,000.7	955.7	871.1
Net funded status	(222)	(182.1)
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation	1,186.2	1,102.1
Accumulated benefit obligation	1,144.2	1,058.6
Fair value of plan assets	952.8	$ 911.6
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	84.5
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	77.5
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	76.4
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	76
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	74.2
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 348.6
Discount rate	2.41%	3.13%
Expected return on plan assets	5.25%	5.75%
Average annual returns over one year (as a percent)	13.00%
Average annual returns over three years (as a percent)	9.00%
Average annual returns over five years (as a percent)	10.00%
Average annual returns over ten years (as a percent)	8.00%
Pension Plans | Germany
Benefit Payments
Discount rate	0.70%
Percentage of German pension plans to total non-U.S. pension plans	92.00%	91.00%
Pension Plans | Foreign Plan [Member]
Funded Status of Pension Plans
Projected benefit obligation	$ 460	$ 369.2	305.6
Defined Benefit Plan, Plan Assets, Amount	28.7	25.2	$ 19.5
Net funded status	(431.3)	(344)
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation	429.4	342.1
Accumulated benefit obligation	384	306.7
Fair value of plan assets	1.3	$ 0.8
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	9.7
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	9.4
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	9.6
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	10.1
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	10.2
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 60.5
Discount rate	0.84%	1.41%
Expected return on plan assets	4.17%	4.43%
Pension Plans | Overfunded Plan [Member] | UNITED STATES
Funded Status of Pension Plans
Projected benefit obligation	$ 36.5	$ 35.6
Defined Benefit Plan, Plan Assets, Amount	47.9	44.1
Net funded status	11.4	8.5
Pension Plans | Unfunded Plan [Member] | UNITED STATES
Funded Status of Pension Plans
Projected benefit obligation	109.9	108.3
Net funded status	(109.9)	(108.3)
Pension Plans | Unfunded Plan [Member] | Foreign Plan [Member]
Funded Status of Pension Plans
Projected benefit obligation	426.5	340.2
Net funded status	(426.5)	(340.2)
Pension Plans | Underfunded Plan [Member] | UNITED STATES
Funded Status of Pension Plans
Projected benefit obligation	1,076.3	993.8
Defined Benefit Plan, Plan Assets, Amount	952.8	911.5
Net funded status	(123.5)	(82.3)
Pension Plans | Underfunded Plan [Member] | Foreign Plan [Member]
Funded Status of Pension Plans
Projected benefit obligation	33.5	29
Defined Benefit Plan, Plan Assets, Amount	28.7	25.2
Net funded status	$ (4.8)	$ (3.8)

Pension Plans and Other Retir_6

Pension Plans and Other Retirement Plans (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plans
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 1,029.4	$ 980.9	$ 890.6
Other Foreign Member [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan Percentage of Certain Specified foreign Plan Assets to Total Foreign Plan Assets	5.00%	4.00%
Foreign Plan [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 28.7	$ 25.2	19.5
Percentage of foreign plan assets to global pension assets	3.00%	3.00%
Expected return on plan assets	4.17%	4.43%
Plan contributions and funding
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 10
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	1.2	$ 1
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Corporate bonds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.5	0.4
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Insurance contracts and other investments
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.5	0.5
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Cash
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.2	0.1
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 2 [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	1	0.9
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 2 [Member] | Corporate bonds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.5	0.4
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 2 [Member] | Insurance contracts and other investments
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.5	0.5
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1 [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.2	0.1
Foreign Plan [Member] | Pension Plans | Fair Value, Inputs, Level 1 [Member] | Cash
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.2	0.1
Foreign Plan [Member] | Pension Plans | Fair Value Measured at Net Asset Value Per Share [Member] | Investments measured at net asset value
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 27.5	$ 24.2
Canada | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Percentage of Plan Assets	100.00%	100.00%
Defined Benefit Plan Percentage of Certain Specified foreign Plan Assets to Total Foreign Plan Assets	95.00%	96.00%
Expected return on plan assets	4.25%
Canada | Pension Plans | Defined Benefit Plan, Equity Securities [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	23.00%
Percentage of Plan Assets	25.00%	25.00%
Canada | Pension Plans | Other Investment [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	12.00%
Percentage of Plan Assets	12.00%	13.00%
Canada | Pension Plans | Bonds
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	65.00%
Percentage of Plan Assets	63.00%	62.00%
UNITED STATES
Plan contributions and funding
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year, Description	Based on the U.S. qualified pension plans’ status as of December 31, 2020, there is a $0.5 million minimum required payment under ERISA for 2021.
UNITED STATES | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Percentage of Plan Assets	100.00%	100.00%
Assets Measured at Fair value	$ 1,000.7	$ 955.7	$ 871.1
Expected return on plan assets	5.25%	5.75%
UNITED STATES | Pension Plans | Defined Benefit Plan, Equity Securities [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	22.00%
Percentage of Plan Assets	23.00%	22.00%
UNITED STATES | Pension Plans | Multi-asset credit [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%
Percentage of Plan Assets	3.00%	3.00%
UNITED STATES | Pension Plans | Liability-hedging assets [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75.00%
Percentage of Plan Assets	74.00%	75.00%
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 29.2	$ 28.5
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Defined Benefit Plan, Common Collective Trust [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	8.1	8
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Annuity and immediate participation contracts
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	21.1	20.5
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 2 [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	29.2	28.5
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 2 [Member] | Defined Benefit Plan, Common Collective Trust [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	8.1	8
UNITED STATES | Pension Plans | Fair Value, Inputs, Level 2 [Member] | Annuity and immediate participation contracts
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	21.1	20.5
UNITED STATES | Pension Plans | Fair Value Measured at Net Asset Value Per Share [Member] | Investments measured at net asset value
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 971.5	$ 927.2

Other Balance Sheet Accounts (D

Other Balance Sheet Accounts (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Current asset, related party	$ 0	$ 173.9
Nontrade Receivables, Current	23.1	24.1
Derivative Asset, Current	2.2	15.6
Income Taxes Receivable	7.6	4.2
Other Assets, Miscellaneous, Current	18.3	17.3
Other current assets	51.2	235.1
Other Current Liabilities
Current liability, related party	0	173.9
Accrued compensation	60.6	53.6
Derivative Liability, Current	21.6	2.6
Environmental contingencies (see Note 10)	13.8	17.8
Pension liabilities included in other current liabilities	15.7	14.8
Accrued interest (see Note 5)	5.8	13.3
Operating Lease, Liability, Current	10.1	9.3
Income taxes payable (see Note 7)	5.1	8.6
Liability for dam spillway replacement, current	20.3	4.7
Other accrued liabilities	95.1	86.1
Other Liabilities, Current	281.9	419.7
Other Liabilities, Noncurrent [Abstract]
Environmental contingencies (see Note 10)	95.4	97.5
Liability for dam spillway replacement, noncurrent	69.3	61.7
Operating Lease, Liability, Noncurrent	25.8	26.2
Legacy Product Liability	24	24
Derivative Liability, Noncurrent	53.9	13.2
Retained obligations of divested businesses	12.2	12.7
Deferred Tax and Other Liabilities, Noncurrent	10.4	7.5
Asset Retirement Obligation	9.6	9.4
Other noncurrent liabilities	19.7	22.4
Other Liabilities, Noncurrent	347.6	308.2
Unrecognized Tax Benefits, Net of Deferred Taxes	3.9	4.1
Contract with Customer, Liability, Current	33.8	35
Contract with Customer, Liability, Noncurrent	$ 23.4	$ 29.5

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Details) $ in Millions	3 Months Ended				12 Months Ended			36 Months Ended	71 Months Ended
	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2020USD ($)shares	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Feb. 03, 2017USD ($)	Dec. 31, 2019USD ($)
Environmental remediation
ZAI PD Account Funding								$ 49.4
ZAI P D Account, Maximum Number of Contingent Deferred Payments					10
Period in Which ZAI PD Contingent Deferred Payments Will be Made					20 years
Minimum ZAI P D Account Assets for Condition in Relation to Contingent Obligation Payments					$ 10
Document Period End Date					Dec. 31, 2020
ZAI PD Claims paid by the Trust									$ 38
ZAI PD Trust Balance					$ 18
ZAI PD Attorney's fees paid by the Trust									15
Frequency of PD Trust Payments					6 months
Estimated annual expenses related to PD Trust					$ 0.2
Estimated liability for environmental investigative and remediation costs		$ 115.3			109.2	$ 115.3			115.3
Pre-tax charges for environmental matters					$ 1.6	1.7	$ 73.8
Legacy Product Charge		24
Remaining Period in Which ZAI PD Contingent Deferred Payments May be Made					18 years
Total Maximum Financial Obligation for ZAI PD Account Contingent Deferred Payments					$ 80
Maximum Annual Obligation for ZAI PD Account Contingent Deferred Payments					8
Repositioning expenses					35	11.1	32.4
ZAI P D Account Contingent Deferred Payment Amount					$ 8
Number of Shares Issuable in Event of Default | shares					77,372,257
ZAI PD Trust [Member] | Minimum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					$ 16
ZAI PD Trust [Member] | Maximum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					24
Spillway [Member]
Environmental remediation
Loss Contingency, Loss in Period	$ 27		$ 45			68
Loss Contingency, Estimate of Possible Loss					95
Spillway [Member] | Minimum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					$ 80
Site Contingency, Time Frame of Disbursements					three
Spillway [Member] | Maximum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					$ 120
Site Contingency, Time Frame of Disbursements					four years
Non Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs		39.3			$ 38	39.3			39.3
Pre-tax charges for environmental matters					1.5	1.7	3.6
Operable Unit 3 [Member]
Environmental remediation
Pre-tax charges for environmental matters				$ 70
Operable Unit 3 [Member] | Minimum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					30
Operable Unit 3 [Member] | Maximum
Environmental remediation
Loss Contingency, Estimate of Possible Loss					170
Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs		$ 76			71.2	76			$ 76
Pre-tax charges for environmental matters					$ 0.1	$ 0	$ 70.2

Commitments and Contingent Li_3

Commitments and Contingent Liabilities (Details 2) $ in Millions	Dec. 31, 2020USD ($)
Financial Guarantee
Financial assurances
Gross financial assurances issued and outstanding	$ 141.1
Surety Bonds
Financial assurances
Gross financial assurances issued and outstanding	77.8
Standby Letters of Credit
Financial assurances
Gross financial assurances issued and outstanding	$ 63.3

Restructuring Expenses and Re_3

Restructuring Expenses and Repositioning Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 1.9	$ 2.6	$ 14
Grace Catalysts Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.8	1.6	13.7
Grace Materials Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.1	1	0.5
Corporate Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 0	$ 0	$ (0.2)

Restructuring Expenses and Re_4

Restructuring Expenses and Repositioning Expenses Restructuring Expenses - Liability Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring Reserve	$ 3.9	$ 3.8	$ 10.7	$ 6.7
Payments	$ (3.1)	(10.2)	$ (6.1)
Currency translation adjustments and other		$ (0.7)

Restructuring Expenses and Re_5

Restructuring Expenses and Repositioning Expenses Repositioning Expenses - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Restructuring and Related Activities [Abstract]
Manufacturing Plants Closed			2
Restructuring Cost and Reserve [Line Items]
Repositioning expenses	$ 35	$ 11.1	$ 32.4
Foreign Currency Transaction Gain (Loss), before Tax		0.7
Restructuring and Related Cost, Incurred Cost	3.2	$ 2.6	10.1
Severance and stock compensation costs related to employee separations [Member]
Restructuring Cost and Reserve [Line Items]
Repositioning expenses			11.7
Write-Off engineering and site costs [Member]
Restructuring Cost and Reserve [Line Items]
Repositioning expenses	19.7		$ 8.5
Advisory fees for review of strategic alternatives
Restructuring Cost and Reserve [Line Items]
Repositioning expenses	$ 7.2

Other Expense, net (Details)

Other Expense, net (Details) $ in Millions	3 Months Ended	6 Months Ended		9 Months Ended	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Other Income and Expenses [Abstract]
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component					$ 79.5	$ 79.9	$ (27.8)
Gain on Business Interruption Insurance Recovery	$ (8)		$ (16.3)	$ (24.3)	(16.3)	(10.7)	0
Hurricane related costs					13.2	0	0
Gain (Loss) on Disposition of Assets included in Other (Income) Expense, net					5.9	4.5	4.9
Third-party acquisition-related costs					5.2	3.6	7.3
Currency transaction effects					(0.1)	(0.8)	(3.6)
Other Nonoperating Income (Expense)					1.6	4.1	(4)
Nonoperating Income (Expense)					$ 89	$ 80.6	$ (23.2)
Hurricane-related Costs Included in Income (Loss) From Equity Method Investments		$ 1.9
Quarters Covered Business Interruption Recoveries [Abstract]				8

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	$ (52.5)	$ 10.6	$ 23.4
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	3	0.3	2.4
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(49.5)	10.9	25.8
Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(0.5)	(0.9)	(1.2)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0.1	0.2	0.3
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(0.4)	(0.7)	(0.9)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	(53.6)	18.5	34.6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	3.7	(2)	(2.2)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(49.9)	16.5	32.4
Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	1.6	(7)	(10)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(0.8)	2.1	4.3
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	$ 0.8	$ (4.9)	$ (5.7)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 234.5	$ 402.2	$ 337	$ 263.3
Other comprehensive income (loss)	(49.5)	10.9	25.8
Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(0.9)	(0.5)	0.2	0.9
OCI before reclassifications	0	0	0
Amounts reclassified from accumulated OCI	(0.4)	(0.7)	(0.9)
Other comprehensive income (loss)	(0.4)	(0.7)	(0.9)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	42.8	92.7	76.2	41.6
OCI before reclassifications	(49.9)	16.5	32.4
Amounts reclassified from accumulated OCI	0	0	0
Other comprehensive income (loss)	(49.9)	16.5	32.4
Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(12.6)	(13.4)	(8.5)	(2.6)
OCI before reclassifications	(33.7)	14	11.1
Amounts reclassified from accumulated OCI	34.5	(18.9)	(16.8)
Other comprehensive income (loss)	0.8	(4.9)	(5.7)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	29.3	78.8	67.9	$ 39.9
OCI before reclassifications	(83.6)	30.5	43.5
Amounts reclassified from accumulated OCI	34.1	(19.6)	(17.7)
Other comprehensive income (loss)	$ (49.5)	$ 10.9	25.8
Accounting Standards Update 2018-02 [Member] | Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			0.2
Accounting Standards Update 2018-02 [Member] | Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			2.2
Accounting Standards Update 2018-02 [Member] | Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			(0.2)
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ 2.2

Shareholders' Equity (Deficit_2

Shareholders' Equity (Deficit) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Authorized shares	300,000,000	300,000,000
Par value of common stock (in dollars per share)	$ 0.01	$ 0.01
Shares reserved for issuance of stock options	6,474,722
Stock options exercised		388,174	243,502
Common stock activity roll forward
Common stock outstanding at the beginning of the period (in shares)	66,735,913	66,792,968	67,780,410
Stock options exercised		388,174	243,502
Shares issued	128,304	94,796	72,590
Shares forfeited through net share exercise		(130,256)	(132,393)
Shares repurchased	(673,807)	(409,769)	(1,171,141)
Common stock outstanding at the end of the period (in shares)	66,190,410	66,735,913	66,792,968
Proceeds from exercise of stock options	$ 0	$ 19.1	$ 6.7
Share-based Payment Arrangement, Nonemployee [Member]
Common stock activity roll forward
Shares issued	15,960
Share-based Payment Arrangement, Employee [Member]
Common stock activity roll forward
Shares issued	112,344

Stock Incentive Plans (Details)

Stock Incentive Plans (Details) - USD ($)	12 Months Ended			16 Months Ended	32 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 08, 2018	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum exercise price to fair market value on the date of grant (as a percent)	100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period				5 years	10 years
Stock Option Activity Roll Forward, Number of Shares
Options exercised (in shares)		(388,174)	(243,502)
Summary of intrinsic value
Intrinsic value for the options exercisable	$ 0				$ 0
Employee nonstatutory stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 9.64	$ 17.94	$ 12.30
Stock Option Activity Roll Forward, Number of Shares
Options outstanding at the beginning of the period (in shares)	1,565,609	1,873,795	1,813,450
Options exercised (in shares)		(388,174)	(243,502)
Options forfeited (in shares)	(26,696)	(35,216)	(90,862)
Options terminated (in shares)	(473,582)	(74,583)	(33,481)
Options granted (in shares)	348,005	189,787	428,190
Options outstanding at the end of the period (in shares)	1,413,336	1,565,609	1,873,795		1,413,336
Stock Option Activity Roll Forward, Average Exercise Price
Average exercise price at the beginning of the period (in dollars per share)	$ 72.30	$ 72.34	$ 72.04
Options exercised (in dollars per share)		74.33	61.92
Options forfeited (in dollars per share)	60.26	71.21	69.82
Options terminated (in dollars per share)	76.67	77.30	75.07
Options granted (in dollars per share)	55.34	78.11	67.36
Average exercise price at the end of the period (in dollars per share)	$ 66.89	$ 72.30	$ 72.34		$ 66.89
Stock Option Activity Roll Forward, Non-vested, Number of Shares
Nonvested options outstanding at the beginning of the period (in shares)	564,663	506,593			564,663
Options granted (in shares)	348,005	189,787	428,190
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	(269,148)
Forfeited (in shares)	(20,787)
Stock Option Activity Roll Forward, Non-vested, Weighted-Average Grant Date Fair Value
Share-based Compensation Arrangement by Share-based Payment Award, Option, Nonvested, Weighted Average Exercise Price	$ 12.16	$ 14.81			$ 12.16
Vested/Exercised (in dollars per share)	13.93
Forfeited (in dollars per share)	$ 9.90
Summary of intrinsic value
Total intrinsic value of all options exercised		$ 800,000	$ 1,600,000
Weighted-average remaining contractual term of exercisable options (in years)	3 years 11 months 12 days
Number Outstanding (in shares)	1,413,336				1,413,336
Number Exercisable (in shares)	848,673				848,673
Employee nonstatutory stock options | Exercise Price Range Seven [Member]
Summary of intrinsic value
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 60
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 70
Number Outstanding (in shares)	640,777				640,777
Number Exercisable (in shares)	522,178				522,178
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	1 year 3 months 21 days
Weighted-Average Exercise Price (in dollars per share)	$ 67.92				$ 67.92
Employee nonstatutory stock options | Exercise Price Range Six [Member]
Summary of intrinsic value
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	50
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 60
Number Outstanding (in shares)	326,051				326,051
Number Exercisable (in shares)	0				0
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 1 day
Weighted-Average Exercise Price (in dollars per share)	$ 0				$ 0
Employee nonstatutory stock options | Exercise Price Range Five [Member]
Summary of intrinsic value
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	40
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 50
Number Outstanding (in shares)	1,802				1,802
Number Exercisable (in shares)	0				0
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	9 years 4 months 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 0				$ 0
Employee nonstatutory stock options | Exercise Price Range Eight [Member]
Summary of intrinsic value
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	70
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 80
Number Outstanding (in shares)	444,706				444,706
Number Exercisable (in shares)	326,495				326,495
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 72.65				$ 72.65
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan vesting period	1 year
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock incentive plan vesting period	3 years

Stock Incentive Plans (Details

Stock Incentive Plans (Details 2) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Options, additional information
Total unrecognized stock-based compensation expense	$ 2.1
Weighted-average period over which this expense will be recognized	9 months 18 days
Share-based Payment Arrangement, Expense, Tax Benefit	$ 0.6	$ 1.9	$ 2.2
Employee nonstatutory stock options
Stock Incentive Plans
Number Outstanding (in shares)	1,413,336
Number Exercisable (in shares)	848,673
Weighted-average remaining contractual term of exercisable options (in years)	3 years 11 months 12 days
Options Granted
Options granted (in shares)	348,005	189,787	428,190
Stock or Unit Option Plan Expense	$ 2.8	$ 3.1	$ 5.8
Assumptions used for estimating the fair value of stock options
Weighted average expected volatility (as a percent)	22.90%	23.00%	23.70%
Risk-free rate	1.18%	2.58%	2.55%
Dividend yield	2.20%	1.40%	1.40%
Volatility rate, maximum	29.40%	23.10%	24.40%
Options, additional information
Volatility rate, minimum	22.70%	22.70%	22.90%
Employee nonstatutory stock options | Minimum
Options, additional information
Expected term	5 years 6 months	5 years 6 months	3 years
Employee nonstatutory stock options | Maximum
Options, additional information
Expected term	6 years 6 months	6 years 6 months	6 years 6 months
Employee nonstatutory stock options | Exercise Price Range Five [Member]
Stock Incentive Plans
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	$ 40
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 50
Number Outstanding (in shares)	1,802
Number Exercisable (in shares)	0
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	9 years 4 months 6 days
Weighted-Average Exercise Price (in dollars per share)	$ 0
Employee nonstatutory stock options | Exercise Price Range Six [Member]
Stock Incentive Plans
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	50
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 60
Number Outstanding (in shares)	326,051
Number Exercisable (in shares)	0
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 1 day
Weighted-Average Exercise Price (in dollars per share)	$ 0
Employee nonstatutory stock options | Exercise Price Range Seven [Member]
Stock Incentive Plans
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	60
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 70
Number Outstanding (in shares)	640,777
Number Exercisable (in shares)	522,178
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	1 year 3 months 21 days
Weighted-Average Exercise Price (in dollars per share)	$ 67.92
Employee nonstatutory stock options | Exercise Price Range Eight [Member]
Stock Incentive Plans
Share-based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit	70
Share-based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit	$ 80
Number Outstanding (in shares)	444,706
Number Exercisable (in shares)	326,495
Share-based Payment Arrangement, Option, Exercise Price Range, Outstanding, Weighted Average Remaining Contractual Term	3 years 10 months 24 days
Weighted-Average Exercise Price (in dollars per share)	$ 72.65
Restricted Stock Units (RSUs) and Performance Stock Units (PSUs) [Member]
Stock Incentive Plans
Share-based Payment Arrangement, Expense	$ 8	$ 9.2	$ 13.2

Stock Incentive Plans Stock Inc

Stock Incentive Plans Stock Incentive Plans Details 3 (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Based Compensation Payout Target	200.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Based Compensation Payout Target	0.00%
Performance Based Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	120,161	88,174	93,216
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Grants in Period, Weighted Average Grant Date Fair Value	$ 55.33	$ 78.11	$ 67.39
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	68,658	57,900	86,698
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Grants in Period, Weighted Average Grant Date Fair Value	$ 55.05	$ 76.91	$ 67.54
Restricted Stock Units (RSUs) and Performance Stock Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 8	$ 9.2	$ 13.2
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures	17,250	17,323	44,279
Percent of Units Expected to Settle in Common Stock	96.00%	96.00%	94.00%
Percent of Units Expected to Settle in Cash	4.00%	4.00%	6.00%
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount	$ 11
Performance Based Units Weighted Average Remaining Service Period	10 months 24 days

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 28, 2020	Feb. 08, 2017
Numerators
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ (43.5)	$ 7	$ (7.3)	$ 42	$ (28.3)	$ 53.7	$ 76.2	$ 24.7	$ (1.8)	$ 126.3	$ 167.6
Denominators
Weighted average common shares-basic calculation									66,300,000	66,800,000	67,200,000
Dilutive effect of employee stock options (in shares)									0	100,000	100,000
Weighted average common shares-diluted calculation									66,300,000	66,900,000	67,300,000
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss)	$ (0.66)	$ 0.11	$ (0.11)	$ 0.63	$ (0.42)	$ 0.81	$ 1.14	$ 0.37	$ (0.03)	$ 1.89	$ 2.49
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss)	$ (0.66)	$ 0.11	$ (0.11)	$ 0.63	$ (0.42)	$ 0.80	$ 1.14	$ 0.37	$ (0.03)	$ 1.89	$ 2.49
Stock options excluded from computation of diluted earnings per share (in shares)									1,600,000	1,000,000	1,700,000
Share Repurchase Program [Line Items]
Stock Repurchase Program, Authorized Amount												$ 250	$ 250
Shares repurchased									673,807	409,769	1,171,141
Payments for Repurchase of Common Stock									$ 40.4	$ 29.8	$ 80
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 235								$ 235
A282017 Share Repurchase Program [Member]
Share Repurchase Program [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount												$ 83

Revenues Revenues - Narrative (

Revenues Revenues - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 31
Number of Reportable Segments | segment	2
Increase (Decrease) in Contract with Customer, Liability	$ (7.4)	$ (5.3)	$ 35.6
Contract With Customer Liability, Noncurrent, Recognition Period	4 years
Revenue, Remaining Performance Obligation, Amount	$ 148

Revenues Schedule of Disaggrega

Revenues Schedule of Disaggregated Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 470.2	$ 419.4	$ 418.7	$ 421.5	$ 504.5	$ 470.5	$ 513.6	$ 469.5	$ 1,729.8	$ 1,958.1	$ 1,932.1
Total North America
Disaggregation of Revenue [Line Items]
Revenues									508.4	597.8	581.7
Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									721	791.6	752.2
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									413.5	475.4	481.5
Latin America
Disaggregation of Revenue [Line Items]
Revenues									86.9	93.3	116.7
Grace Catalysts Technologies
Disaggregation of Revenue [Line Items]
Revenues									1,271.4	1,496.7	1,463.5
Grace Catalysts Technologies | Total North America
Disaggregation of Revenue [Line Items]
Revenues									388.9	482.8	475.4
Grace Catalysts Technologies | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									510.8	571.4	521.4
Grace Catalysts Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									321.5	385.4	386.6
Grace Catalysts Technologies | Latin America
Disaggregation of Revenue [Line Items]
Revenues									50.2	57.1	80.1
Grace Catalysts Technologies | Refining Catalysts [Member]
Disaggregation of Revenue [Line Items]
Revenues									649.8	791.4	802
Grace Catalysts Technologies | Refining Catalysts [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									216.6	291.4	282.8
Grace Catalysts Technologies | Refining Catalysts [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									279.1	288.4	266
Grace Catalysts Technologies | Refining Catalysts [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									120.4	171.7	193.4
Grace Catalysts Technologies | Refining Catalysts [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									33.7	39.9	59.8
Grace Catalysts Technologies | Polyolefin and Chemical Catalysts [Member]
Disaggregation of Revenue [Line Items]
Revenues									621.6	705.3	661.5
Grace Catalysts Technologies | Polyolefin and Chemical Catalysts [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									172.3	191.4	192.6
Grace Catalysts Technologies | Polyolefin and Chemical Catalysts [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									231.7	283	255.4
Grace Catalysts Technologies | Polyolefin and Chemical Catalysts [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									201.1	213.7	193.2
Grace Catalysts Technologies | Polyolefin and Chemical Catalysts [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									16.5	17.2	20.3
Grace Materials Technologies
Disaggregation of Revenue [Line Items]
Revenues									458.4	461.4	468.6
Grace Materials Technologies | Total North America
Disaggregation of Revenue [Line Items]
Revenues									119.5	115	106.3
Grace Materials Technologies | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									210.2	220.2	230.8
Grace Materials Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									92	90	94.9
Grace Materials Technologies | Latin America
Disaggregation of Revenue [Line Items]
Revenues									36.7	36.2	36.6
Grace Materials Technologies | Consumer/Pharma [Member]
Disaggregation of Revenue [Line Items]
Revenues									162.5	144.6	132.6
Grace Materials Technologies | Consumer/Pharma [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									61.5	45.2	36.2
Grace Materials Technologies | Consumer/Pharma [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									60.9	59.1	58
Grace Materials Technologies | Consumer/Pharma [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									19.8	20.1	19
Grace Materials Technologies | Consumer/Pharma [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									20.3	20.2	19.4
Grace Materials Technologies | Coatings [Member]
Disaggregation of Revenue [Line Items]
Revenues									137.5	139.8	155.4
Grace Materials Technologies | Coatings [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									25.4	25.9	28.1
Grace Materials Technologies | Coatings [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									66.6	67.8	75.3
Grace Materials Technologies | Coatings [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									35.8	36.9	43.3
Grace Materials Technologies | Coatings [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									9.7	9.2	8.7
Grace Materials Technologies | Chemical process [Member]
Disaggregation of Revenue [Line Items]
Revenues									140.6	156.1	157.3
Grace Materials Technologies | Chemical process [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									28.5	38.1	35.2
Grace Materials Technologies | Chemical process [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									69.4	79.1	81.6
Grace Materials Technologies | Chemical process [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									36.1	32.3	32.2
Grace Materials Technologies | Chemical process [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									6.6	6.6	8.3
Grace Materials Technologies | Other materials [Member]
Disaggregation of Revenue [Line Items]
Revenues									17.8	20.9	23.3
Grace Materials Technologies | Other materials [Member] | Total North America
Disaggregation of Revenue [Line Items]
Revenues									4.1	5.8	6.8
Grace Materials Technologies | Other materials [Member] | Europe Middle East Africa
Disaggregation of Revenue [Line Items]
Revenues									13.3	14.2	15.9
Grace Materials Technologies | Other materials [Member] | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues									0.3	0.7	0.4
Grace Materials Technologies | Other materials [Member] | Latin America
Disaggregation of Revenue [Line Items]
Revenues									$ 0.1	$ 0.2	$ 0.2

Revenues Schedule of Deferred R

Revenues Schedule of Deferred Revenues (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Contract with Customer, Liability, Current	$ 33.8	$ 35
Contract with Customer, Liability, Noncurrent	23.4	29.5
Contract with Customer, Liability	$ 57.2	$ 64.5

Revenues Schedule of Remaining

Revenues Schedule of Remaining Performance Obligations (Details)	Dec. 31, 2020
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Percentage	27.00%
Revenue, Remaining Performance Obligation, Percentage	27.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Percentage	19.00%
Revenue, Remaining Performance Obligation, Percentage	19.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Percentage	17.00%
Revenue, Remaining Performance Obligation, Percentage	17.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Percentage	16.00%
Revenue, Remaining Performance Obligation, Percentage	16.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	6 years
Revenue, Remaining Performance Obligation, Percentage	21.00%
Revenue, Remaining Performance Obligation, Percentage	21.00%

Operating Segment Information -

Operating Segment Information - Segment Info and Reconciliation (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Operating segment information
Number of Reportable Segments | segment									2
Net Sales
Revenues	$ 470.2	$ 419.4	$ 418.7	$ 421.5	$ 504.5	$ 470.5	$ 513.6	$ 469.5	$ 1,729.8	$ 1,958.1	$ 1,932.1
Adjusted EBIT
Adjusted EBIT									312.2	473.1	457.1
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization									105	100.3	100.8
Property, Plant and Equipment, Additions									157.6	194.1	216.3
Assets
Total Assets	3,765.5				3,932.6				3,765.5	3,932.6	3,565.3
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Adjusted EBIT									312.2	473.1	457.1
Costs related to legacy matters									(39.4)	(103.5)	(82.3)
Pension MTM adjustment and other related costs, net									(94.6)	(85.9)	15.2
Restructuring and repositioning expenses									(36.9)	(13.7)	(46.4)
Adjusted EBIT Benefit Plan Adjustment									0	(5)	0
Third-party acquisition-related costs									(5.2)	(3.6)	(7.3)
Taxes and interest included in equity in earnings of unconsolidated affiliate									(0.7)	0.1	(0.4)
Adjusted EBIT inventory write-off			$ (19.7)						(20.7)	(3.6)	0
Amortization of Acquired Inventory Fair Value Adjustment									0	0	(6.9)
Loss on early extinguishment of debt		$ (39.4)							(39.4)	0	(4.8)
Interest expense, net									(74.9)	(74.8)	(78.5)
Net Income (Loss) Attributable to Noncontrolling Interest									0.1	0.4	(0.8)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									$ 0.5	183.5	244.9
Catalysts Technologies
Operating segment information
Number of operating segments | segment									2
Net Sales
Revenues									$ 1,271.4	1,496.7	1,463.5
Adjusted EBIT
Operating income (loss)									309.6	466.4	440.9
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization									85.3	81.9	81.7
Property, Plant and Equipment, Additions									107.8	114.6	150.3
Assets
Total Assets	2,294.9				2,556.1				2,294.9	2,556.1	2,326.6
Materials Technologies
Net Sales
Revenues									458.4	461.4	468.6
Adjusted EBIT
Operating income (loss)									85	97.8	105.6
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization									15	14.2	15.5
Property, Plant and Equipment, Additions									36.2	68.8	56.1
Assets
Total Assets	448.2				430.3				448.2	430.3	375.9
Corporate Segment [Member]
Adjusted EBIT
Operating income (loss)									(68)	(72.7)	(73.5)
Certain Pension Costs									(14.4)	(18.4)	(15.9)
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization									4.7	4.2	3.6
Property, Plant and Equipment, Additions									13.6	10.7	9.9
Assets
Total Assets	$ 1,022.4				$ 946.2				$ 1,022.4	$ 946.2	$ 862.8

Operating Segment Information_2

Operating Segment Information - Sales and Long-Lived Assets by Geographical Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Geographic Area Data
Revenues	$ 470.2	$ 419.4	$ 418.7	$ 421.5	$ 504.5	$ 470.5	$ 513.6	$ 469.5	$ 1,729.8	$ 1,958.1	$ 1,932.1
Long-Lived Assets	1,208.8				1,317.7				1,208.8	1,317.7	1,110.5
Total North America
Geographic Area Data
Revenues									508.4	597.8	581.7
Long-Lived Assets	822.3				956.8				822.3	956.8	809.5
United States
Geographic Area Data
Revenues									459.8	540.2	533.8
Long-Lived Assets	799.1				937.9				799.1	937.9	793
Canada
Geographic Area Data
Revenues									48.6	57.6	47.9
Long-Lived Assets	23.2				18.9				23.2	18.9	16.5
Europe Middle East Africa
Geographic Area Data
Revenues									721	791.6	752.2
Long-Lived Assets	308.4				273.4				308.4	273.4	221.4
Germany
Geographic Area Data
Long-Lived Assets	267.4				228.2				267.4	228.2	172.5
EMEA excluding Germany [Member]
Geographic Area Data
Long-Lived Assets	41				45.2				41	45.2	48.9
Asia Pacific
Geographic Area Data
Revenues									413.5	475.4	481.5
Long-Lived Assets	72.2				80.3				72.2	80.3	72.9
Latin America
Geographic Area Data
Revenues									86.9	93.3	116.7
Long-Lived Assets	$ 5.9				$ 7.2				$ 5.9	$ 7.2	$ 6.7

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment, ownership interest	50.00%								50.00%
Investment in unconsolidated affiliate	$ 175,500,000				$ 181,900,000				$ 175,500,000	$ 181,900,000
Equity in earnings of unconsolidated affiliates									13,500,000	27,800,000	$ 31,800,000
Related party transactions:
Product manufactured for ART									261,100,000	260,800,000	229,100,000
Related Party Transaction, markup of product manufactured for ART reducing COGS									5,100,000	5,100,000	4,500,000
Charges for fixed costs, research and development and selling, general and administrative services to ART									54,300,000	51,100,000	41,800,000
Schedule of Investments [Line Items]
Current asset, related party	0				173,900,000				0	173,900,000
Current liability, related party	0				173,900,000				0	173,900,000
Net income (loss) attributable to W. R. Grace & Co. shareholders	(43,500,000)	$ 7,000,000	$ (7,300,000)	$ 42,000,000	(28,300,000)	$ 53,700,000	$ 76,200,000	$ 24,700,000	(1,800,000)	126,300,000	167,600,000
Liabilities	3,531,000,000				3,530,400,000				3,531,000,000	3,530,400,000
Assets, Current	875,300,000				1,134,900,000				875,300,000	1,134,900,000
Assets	3,765,500,000				3,932,600,000				3,765,500,000	3,932,600,000	3,565,300,000
Liabilities, Current	559,300,000				745,100,000				559,300,000	745,100,000
Revenues	470,200,000	419,400,000	418,700,000	421,500,000	504,500,000	470,500,000	513,600,000	469,500,000	1,729,800,000	1,958,100,000	1,932,100,000
Cost of goods sold									1,113,300,000	1,164,400,000	1,165,400,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									500,000	183,500,000	244,900,000
Operating Income Included in Income (Loss) from Equity Method Investments									17,500,000	28,200,000	32,700,000
Depreciation and Amortization Included in Income (Loss) From Equity Method Investments									(3,300,000)	(500,000)	(500,000)
Interest Expense and Income Taxes Included in Income (Loss) From Equity Method Investments									(700,000)	100,000	(400,000)
Equity in earnings of unconsolidated affiliates									13,500,000	27,800,000	31,800,000
Assets, Current	875,300,000				1,134,900,000				875,300,000	1,134,900,000
Assets	3,765,500,000				3,932,600,000				3,765,500,000	3,932,600,000	3,565,300,000
Liabilities, Current	559,300,000				745,100,000				559,300,000	745,100,000
Liabilities	3,531,000,000				3,530,400,000				3,531,000,000	3,530,400,000
Revenues	470,200,000	419,400,000	418,700,000	421,500,000	504,500,000	470,500,000	513,600,000	469,500,000	1,729,800,000	1,958,100,000	1,932,100,000
Cost of goods sold									1,113,300,000	1,164,400,000	1,165,400,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									500,000	183,500,000	244,900,000
Net income (loss) attributable to W. R. Grace & Co. shareholders	(43,500,000)	$ 7,000,000	$ (7,300,000)	$ 42,000,000	(28,300,000)	$ 53,700,000	$ 76,200,000	$ 24,700,000	(1,800,000)	126,300,000	167,600,000
Grace LOC to ART [Member]
Schedule of Investments [Line Items]
Long-term Line of Credit	0				0				0	0
ART [Member]
Schedule of Investments [Line Items]
Net income (loss) attributable to W. R. Grace & Co. shareholders									27,000,000	56,500,000	64,200,000
Liabilities	173,300,000				177,400,000				173,300,000	177,400,000
Assets, Current	286,400,000				300,700,000				286,400,000	300,700,000
Assets, Noncurrent	235,800,000				237,800,000				235,800,000	237,800,000
Assets	522,200,000				538,500,000				522,200,000	538,500,000
Liabilities, Current	173,000,000				177,100,000				173,000,000	177,100,000
Liabilities, Noncurrent	300,000				300,000				300,000	300,000
Revenues									481,900,000	527,500,000	487,500,000
Cost of goods sold									431,400,000	453,400,000	410,600,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									28,200,000	59,000,000	65,500,000
Assets, Current	286,400,000				300,700,000				286,400,000	300,700,000
Assets, Noncurrent	235,800,000				237,800,000				235,800,000	237,800,000
Assets	522,200,000				538,500,000				522,200,000	538,500,000
Liabilities, Current	173,000,000				177,100,000				173,000,000	177,100,000
Liabilities, Noncurrent	300,000				300,000				300,000	300,000
Liabilities	173,300,000				177,400,000				173,300,000	177,400,000
Revenues									481,900,000	527,500,000	487,500,000
Cost of goods sold									431,400,000	453,400,000	410,600,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest									28,200,000	59,000,000	65,500,000
Net income (loss) attributable to W. R. Grace & Co. shareholders									27,000,000	56,500,000	64,200,000
Grace LOC to ART [Member]
Schedule of Investments [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	15,000,000								$ 15,000,000
Commitment fee on credit facility									0.10%
Chevron LOC to ART [Member]
Schedule of Investments [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	15,000,000								$ 15,000,000
Commitment fee on credit facility									0.10%
Affiliated Entity [Member]
Schedule of Investments [Line Items]
Trade accounts receivable	2,200,000				3,600,000				$ 2,200,000	3,600,000
Revenue from Related Parties									11,300,000	11,800,000	$ 14,000,000
ART [Member]
Schedule of Investments [Line Items]
Trade accounts receivable	28,300,000				17,500,000				28,300,000	17,500,000
Current asset, related party	0				173,900,000				0	173,900,000
Accounts payable	19,800,000				37,700,000				19,800,000	37,700,000
Debt payable within one year	3,500,000				9,900,000				3,500,000	9,900,000
Debt payable after one year	22,100,000				37,500,000				22,100,000	37,500,000
Current liability, related party	$ 0				$ 173,900,000				$ 0	$ 173,900,000
Debt Instrument, Frequency of Periodic Payment									monthly
Debt Instrument, Basis Spread on Variable Rate									1.25%
Debt Instrument, Maturity Date, Description									8 years
Joint Venture [Member]
Schedule of Investments [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	87.50%				87.50%				87.50%	87.50%

Acquisition Acquisition - Asset

Acquisition Acquisition - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 562.7	$ 556.9	$ 540.4

Acquisition Acquisition- Narrat

Acquisition Acquisition- Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		$ 2	$ 22.8	$ 418
Goodwill		$ 562.7	556.9	540.4
Polyolefin Catalysts Business of Albemarle Corporation [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired				$ 418
Rive Technology, Inc.
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 2		$ 22.8

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Environmental remediation
Provision for environmental remediation									$ 1.6	$ 1.7	$ 73.8
Loss on early extinguishment of debt		$ 39.4							39.4	0	4.8
Revenues	$ 470.2	419.4	$ 418.7	$ 421.5	$ 504.5	$ 470.5	$ 513.6	$ 469.5	1,729.8	1,958.1	1,932.1
Gross Profit	181.2	156.4	119.3	159.6	204.7	191	209.4	188.6	616.5	793.7	766.7
Net income (loss)	(40.9)	6.7	(9.6)	42.1	(28.1)	53.8	76.4	24.6	(1.7)	126.7	166.8
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ (43.5)	$ 7	$ (7.3)	$ 42	$ (28.3)	$ 53.7	$ 76.2	$ 24.7	$ (1.8)	$ 126.3	$ 167.6
Basic earnings per share:
Net income (loss)	$ (0.66)	$ 0.11	$ (0.11)	$ 0.63	$ (0.42)	$ 0.81	$ 1.14	$ 0.37	$ (0.03)	$ 1.89	$ 2.49
Diluted earnings per share:
Net income (loss)	(0.66)	0.11	(0.11)	0.63	(0.42)	0.80	1.14	0.37	(0.03)	1.89	2.49
Dividends per common share	$ 0.30	$ 0.30	$ 0.30	$ 0.30	$ 0.27	$ 0.27	$ 0.27	$ 0.27	$ 1.20	$ 1.08	$ 0.96
Spillway [Member]
Environmental remediation
Loss Contingency, Loss in Period		$ 27						$ 45		$ 68

SCHEDULE II-VALUATION AND QUA_2

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation and qualifying accounts deducted from assets and Reserves:
Change in valuation allowance	$ 14.6	$ 4.2	$ 7.9
Allowances for notes and accounts receivable [Member]
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	13.7	12	12
Additions charged to costs and expenses	0.6	3.2	0
Deductions	(12.1)	(1.5)	0
Other net	0.1	0	0
Balance at end of period	2.3	13.7	12
Valuation allowance for deferred tax assets
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	24.1	19.9	12
Additions charged to costs and expenses	15.5	9.2	10.7
Deductions	(0.9)	(5)	(2.8)
Other net	0	0	0
Balance at end of period	$ 38.7	$ 24.1	$ 19.9

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - Fine Chemistry Services Business of Albemarle Corporation $ in Millions	Feb. 25, 2021USD ($)
Subsequent Event [Line Items]
Subsequent Event, Date	Feb. 25, 2021
Cash to be paid at closing	$ 300
Business Acquisition, Equity Interest to be Issued or Issuable, Value Assigned	270
Expected Acquisition Price	$ 570