W.R. Grace & Co. (GRA) 10-K 22 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	W R GRACE & CO
Entity Central Index Key	1,045,309
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 4,876,308,803
Entity Common Stock, Shares Outstanding		67,693,241
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net sales	$ 1,716.5	$ 1,598.6	$ 1,628.2
Cost of goods sold	1,053.2	942.7	976.5
Gross profit	663.3	655.9	651.7
Selling, general and administrative expenses	302.6	308.8	318.9
Research and development expenses	53.5	48.8	47.1
Restructuring and repositioning expenses	26.7	38.6	20.4
Equity in earnings of unconsolidated affiliate	(25.9)	(29.8)	(20.4)
Provision for environmental remediation	24.4	28.7	6.4
Interest expense and related financing costs	79.5	81.5	99.4
Other (income) expense, net	8.4	(13.3)	13.8
Total costs and expenses	452.4	489.9	458
Income (loss) from continuing operations before income taxes	210.9	166	193.7
(Provision for) benefit from income taxes	(200.5)	(59)	(69.8)
Income (loss) from continuing operations	10.4	107	123.9
Income (loss) from discontinued operations, net of income taxes	0	(12.9)	20.2
Net income (loss)	10.4	94.1	144.1
Less: Net (income) loss attributable to noncontrolling interests	0.8	0	0.1
Net income (loss) attributable to W. R. Grace & Co. shareholders	11.2	94.1	144.2
Net Income (Loss) Available to Common Stockholders, Basic [Abstract]
Income (loss) from continuing operations attributable to W. R. Grace & Co. shareholders	$ 11.2	$ 107	$ 124
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations	$ 0.16	$ 1.53	$ 1.72
Income (loss) from discontinued operations, net of income taxes	0	(0.19)	0.28
Net income (loss)	$ 0.16	$ 1.34	$ 2
Weighted average number of basic shares	68.1	70.1	72
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations	$ 0.16	$ 1.52	$ 1.71
Income (loss) from discontinued operations, net of income taxes	0	(0.19)	0.28
Net income (loss)	$ 0.16	$ 1.33	$ 1.99
Weighted average number of diluted shares	68.2	70.5	72.6
Dividends per common share	$ 0.84	$ 0.51	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 10.4	$ 94.1	$ 144.1
Other comprehensive income (loss):
Defined benefit pension and other postretirement plans	(1.3)	(0.6)	(1)
Currency translation adjustments	(26)	(1.8)	(43.3)
Gain (loss) from hedging activities	0.8	0.3	1.3
Total other comprehensive income (loss) attributable to noncontrolling interests	0	2.6	0.2
Total other comprehensive income (loss), net of income taxes	(26.5)	0.5	(42.8)
Comprehensive income (loss)	(16.1)	94.6	101.3
Less: comprehensive (income) loss attributable to noncontrolling interests	0.8	(2.6)	(0.1)
Comprehensive income (loss) attributable to W. R. Grace & Co. shareholders	$ (15.3)	$ 92	$ 101.2

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income (loss)	$ 10.4	$ 94.1	$ 144.1
Income (loss) from discontinued operations, net of income taxes	0	12.9	(20.2)
Income (loss) from continuing operations	10.4	107	123.9
Reconciliation to net cash provided by operating activities:
Depreciation and amortization	111.5	100.3	99.2
Equity in earnings of unconsolidated affiliate	(25.9)	(29.8)	(20.4)
Dividends received from unconsolidated affiliate	19	31	11.8
Costs related to legacy product, environmental and other claims	30.8	35.4	6.1
Cash paid for legacy product, environmental and other claims	54.5	24.6	507.4
Provision for (benefit from) income taxes	200.5	59	69.8
Income Taxes Paid	61.8	96.6	40.7
Proceeds from Income Tax Refunds	34.2	11.4	5.9
Interest expense and related financing costs	79.5	81.5	99.4
Interest Paid	70.2	75.7	89.5
Loss on early extinguishment of debt	0	11.1	0
Defined benefit pension expense (income)	64.1	72.6	50.9
Cash paid under defined benefit pension arrangements	(17.8)	(15.9)	(15.4)
Accounts receivable reserve—Venezuela	10	0	0
Restructuring expenses	11.5	24.3	11.3
Cash paid for restructuring	(14.4)	(16)	(5.6)
Changes in assets and liabilities, excluding effect of currency translation:
Trade accounts receivable	(4.9)	(15.7)	(18)
Inventories	4.4	(0.6)	3.8
Accounts payable	(2.5)	32	7.3
All other items, net	(7.6)	(14.9)	23.5
Net cash provided by (used for) operating activities from continuing operations	319.2	267.5	(189.8)
INVESTING ACTIVITIES
Capital expenditures	(125.2)	(116.9)	(118.8)
Business acquired	(3.5)	(246.5)	0
Proceeds from sale of assets	0.6	13.7	0
Other investing activities	(1.8)	4.7	6.8
Net cash provided by (used for) investing activities from continuing operations	(129.9)	(345)	(112)
FINANCING ACTIVITIES
Borrowings under credit arrangements	114.4	39.4	292.4
Repayments under credit arrangements	(143.9)	(633)	(50)
Cash paid for repurchases of common stock	(65)	(195.1)	(301.5)
Proceeds from exercise of stock options	16.4	17	26.9
Dividends paid	(57.3)	(36)	0
Distribution from GCP	0	750	0
Other financing activities	0.6	(2.5)	(8.3)
Net cash provided by (used for) financing activities from continuing operations	(134.8)	(60.2)	(40.5)
Effect of currency exchange rate changes on cash and cash equivalents	7.7	(3)	(1.7)
Increase (decrease) in cash and cash equivalents from continuing operations	62.2	(140.7)	(344)
Cash flows from discontinued operations
Net cash provided by (used for) operating activities	0	23.9	202.5
Net cash provided by (used for) investing activities	0	(9.5)	(32.4)
Net cash provided by (used for) financing activities	0	31.4	2.9
Effect of currency exchange rate changes on cash and cash equivalents	0	(1)	(56.6)
Increase (decrease) in cash and cash equivalents from discontinued operations	0	44.8	116.4
Net increase (decrease) in cash and cash equivalents	62.2	(95.9)	(227.6)
Less: cash and cash equivalents of discontinued operations	0		0
Cash and cash equivalents, beginning of period	90.6
Cash and cash equivalents, end of period	152.8	90.6
Supplemental disclosure of cash flow information
Capital expenditures in accounts payable	41.4	23.8	29.4
Net share settled stock option exercises	$ 1.2	10.5	0
Scenario, Previously Reported [Member]
Cash flows from discontinued operations
Cash and cash equivalents, beginning of period		$ 329.9	557.5
Cash and cash equivalents, end of period			$ 329.9

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 152.8	$ 90.6
Restricted cash and cash equivalents	10.7	10
Trade accounts receivable, less allowance of $11.7 (2016—$2.2)	285.2	273.9
Inventories	230.9	228
Other current assets	49	52.3
Total Current Assets	728.6	654.8
Properties and equipment, net of accumulated depreciation and amortization of $1,463.4 (2016—$1,327.5)	799.1	729.6
Goodwill	402.4	394.2
Technology and other intangible assets, net	255.4	269.1
Deferred income taxes	556.5	709.4
Investment in unconsolidated affiliate	125.9	117.6
Other assets	39.1	37.1
Total Assets	2,907	2,911.8
Current Liabilities
Debt payable within one year	20.1	76.5
Accounts payable	210.3	195.4
Other current liabilities	217.8	208.9
Total Current Liabilities	448.2	480.8
Debt payable after one year	1,523.8	1,507.6
Underfunded and unfunded defined benefit pension plans	502.4	424.3
Other liabilities	169.3	126.7
Total Liabilities	2,643.7	2,539.4
Commitments and Contingencies—Note 10
Equity
Common stock issued, par value $0.01; 300,000,000 shares authorized; outstanding: 67,780,410 (2016—68,309,431)	0.7	0.7
Paid-in capital	474.8	487.3
Retained earnings	573.1	619.3
Treasury stock, at cost: shares: 9,676,217 (2016—9,147,196)	(832.1)	(804.9)
Accumulated other comprehensive income (loss)	39.9	66.4
Total W. R. Grace & Co. Shareholders' Equity	256.4	368.8
Noncontrolling interests	6.9	3.6
Total Equity	263.3	372.4
Total Liabilities and Equity	$ 2,907	$ 2,911.8

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Trade accounts receivable, allowance (in dollars)	$ 11.7	$ 2.2
Properties and equipment, accumulated depreciation and amortization	$ 1,463.4	$ 1,327.5
Common stock issued, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued, shares authorized	300,000,000	300,000,000
Common stock issued, shares outstanding	67,780,410	68,309,431
Treasury Stock, Shares	9,676,217	9,147,196

Consolidated Statements of Equi

Consolidated Statements of Equity Statement - USD ($) $ in Millions	Total	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]	Net Income including Noncontrolling Interest [Member]
Beginning Balance at Dec. 31, 2014	$ 369	$ 526.8	$ 292.1	$ (429.2)	$ (23.8)	$ 3.1
Net income (loss)	144.1		144.2			0.7	$ 144.9
Repurchase of common stock	(301.5)			(301.5)
Stock-based compensation	13	13
Exercise of stock options	26.9	(45.4)		72.3
Purchase of noncontrolling interest	0	(0.7)				0.7
Tax benefit related to stock plans	1.9	1.9	0
Shares issued	1.1	1.1
Other comprehensive income (loss)	(42.8)				(43)
Other comprehensive income (loss)	0.2
Ending Balance at Dec. 31, 2015	212.5	496.7	436.3	(658.4)	(66.8)	4.7
Net income (loss)	94.1		94.1			0
Repurchase of common stock	(195.1)			(195.1)
Stock-based compensation	11.6	11.6
Exercise of stock options	27.5	(21.1)		48.6
Tax benefit related to stock plans	70.4	0	70.4
Shares issued	0.8	0.8
Dividends declared	(36)		(36)
Other comprehensive income (loss)	0.5				(2.1)
Other comprehensive income (loss)	2.6
Distribution of GCP	186.1		54.5		135.3	(3.7)
Ending Balance at Dec. 31, 2016	372.4	488	619.3	(804.9)	66.4	3.6
Net income (loss)	10.4		11.2			(0.8)
Repurchase of common stock	(65)			(65)
Stock-based compensation	11	11
Exercise of stock options	16.1	(18.9)		35
Adjustment to Additional Paid In Capital, Tax Payments Related to Stock-based Compensation	(2.5)	(2.5)
Shares issued	0.7	(2.1)		2.8
Dividends, Common Stock	57.4		57.4
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	4.1					4.1
Other comprehensive income (loss)	(26.5)				(26.5)
Other comprehensive income (loss)	0
Ending Balance at Dec. 31, 2017	$ 263.3	$ 475.5	$ 573.1	$ (832.1)	$ 39.9	$ 6.9

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies	12 Months Ended
	Dec. 31, 2017
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 specialty chemicals and specialty materials businesses on a global basis through two reportable segments: Grace Catalysts Technologies, which includes catalysts and related products and technologies used in refining, petrochemical and other chemical manufacturing applications; and Grace Materials Technologies, which includes specialty materials, including silica-based and silica-alumina-based materials, used in coatings, consumer, industrial, and pharmaceutical 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. Separation Transaction On January 27, 2016, Grace entered into a separation agreement with GCP Applied Technologies Inc., then a wholly-owned subsidiary of Grace ("GCP"), pursuant to which Grace agreed to transfer its Grace Construction Products operating segment and the packaging technologies business of its Grace Materials Technologies operating segment to GCP (the "Separation"). Grace and GCP completed the Separation on February 3, 2016 (the "Distribution Date"), by means of a pro rata distribution to the Company's stockholders of all of the outstanding shares of GCP common stock (the "Distribution"), with one share of GCP common stock distributed for each share of Company common stock held as of the close of business on January 27, 2016. As a result of the Distribution, GCP became an independent public company. GCP’s historical financial results through the Distribution Date are reflected in Grace’s Consolidated Financial Statements as discontinued operations. 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 certain 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 and Chief Operating 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 amount 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: • 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 19 ); and • Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate obligation, such as litigation (see Note 10 ), income taxes (see Note 7 ), and environmental remediation (see Note 10 ). Revenue Recognition Grace recognizes revenue when all of the following criteria are satisfied: risk of loss and title transfer to the customer; the price is fixed and determinable; persuasive evidence of a sales arrangement exists; and collectability is reasonably assured. The point at which risk of loss and title transfers to a customer is determined based on delivery terms, which are generally included in customer contracts of sale, order confirmation documents, and invoices. 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 market. 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, 3 to 10 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. Grace is currently in the process of conducting a depreciation study to review the useful lives of machinery and equipment, including an evaluation of historical retirement data as well as industry review and analysis. This evaluation will be completed by the end of the 2018 first quarter. Grace expects this review to result in increased useful lives (and lower depreciation expense) and will apply the change to new and existing assets on a prospective basis as a change in accounting estimate effective January 1, 2018. 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. 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 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. 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. 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 performance based units (CSPBU) 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 May 2014, the FASB issued ASU 2014-09 "Revenue from Contracts with Customers." This update is intended to remove inconsistencies and weaknesses in revenue requirements; provide a more robust framework for addressing revenue issues; improve comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets; provide more useful information to users of financial statements through improved disclosure requirements; and simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. The standard allows for two methods of adoption: (a) full retrospective adoption, meaning the standard is applied to all periods presented, or (b) modified retrospective adoption, meaning the cumulative effect of applying the new standard is recognized as an adjustment to the opening retained earnings balance. Grace has assessed specific areas of the standard and its impact on the Consolidated Financial Statements. Grace will adopt this standard in the 2018 first quarter under the modified retrospective approach and does not expect it to have a material effect on the Consolidated Financial Statements. In February 2016, the FASB issued ASU 2016-02 "Leases (Topic 842)." This update is intended to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The core principle of Topic 842 is that a lessee should recognize the assets and liabilities that arise from leases. A lessee should recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term, including optional payments where they are reasonably certain to occur. Currently, as a lessee, Grace is a party to a number of leases which, under existing guidance, are classified as operating leases and not recorded on the balance sheet but are expensed as incurred. Under the new standard, many of these leases will be recorded on the Consolidated Balance Sheets. Grace will adopt the standard in the 2019 first quarter and at this time cannot reasonably estimate the effect of adoption. In November 2016, the FASB issued ASU 2016-18 "Statement of Cash Flows (Topic 230): Restricted Cash," which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. Grace will adopt the update in the 2018 first quarter and does not expect it to have a material effect on the Consolidated Financial Statements. As of December 31, 2017 and 2016, restricted cash included in the Consolidated Balance Sheets was $10.7 million and $10.0 million , respectively. In January 2017, the FASB issued ASU 2017-01 "Business Combinations (Topic 805)," which provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If the screen is not met, the amendments in this update (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output, and (2) remove the evaluation of whether a market participant could replace missing elements. The amendments in this update also narrow the definition of the term "output" so that the term is consistent with how outputs are described in Topic 606. Public business entities are required to apply the amendments in this update to annual periods beginning after December 15, 2017, including interim periods within those periods, with early application permitted. Grace will adopt the update when it becomes effective and does not expect it to have a material effect on the Consolidated Financial Statements. In January 2017, the FASB issued ASU 2017-04 "Intangibles—Goodwill and Other (Topic 350)." This update modifies the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination ("Step 2"). Because these amendments eliminate Step 2 from the goodwill impairment test, they should reduce the cost and complexity of evaluating goodwill for impairment. Grace is required to adopt the amendments in this update for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Grace is currently evaluating the timing of adoption and does not expect the update to have a material effect on the Consolidated Financial Statements. In March 2017, the FASB issued ASU 2017-07 "Compensation—Retirement Benefits (Topic 715)." This update requires that the service cost component of net benefit cost be presented with other compensation costs arising from services rendered. The remaining net benefit cost is either presented as a line item in the statement of operations outside of a subtotal for income from operations, if presented, or disclosed separately. Only the service cost component of net benefit expense can be capitalized. The update will affect the classification of defined benefit pension expense within the Consolidated Statements of Operations, with changes to amounts included in "cost of goods sold," "selling, general and administrative expenses," "research and development expenses," and "other (income) expense, net." Grace will adopt the update in the 2018 first quarter. In May 2017, the FASB issued ASU 2017-09 "Compensation—Stock Compensation (Topic 718)." This update clarifies the existing definition of the term "modification," which is currently defined as "a change in any of the terms or conditions of a share-based payment award." The update requires entities to account for modifications of share-based payment awards unless the (1) fair value, (2) vesting conditions, and (3) classification as an equity instrument or a liability instrument of the modified award are the same as of the original award before modification. Grace is required to adopt the amendments in this update for fiscal years and interim periods beginning after December 15, 2017, with early adoption permitted. Grace does not currently have any modifications of share-based awards and will adopt the update when it becomes effective. In January 2018, the FASB issued ASU 2018-01 "Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842." This update provides an optional transition practical expedient that allows an entity to elect not to evaluate under Topic 842 existing or expired land easements not previously accounted for as leases. All land easements entered into or modified after the adoption of Topic 842 must be evaluated under Topic 842. Grace, which typically does not account for easements under current lease accounting, will use the transition practical expedient when adopting Topic 842 in the 2019 first quarter and at this time cannot reasonably estimate the effect of adoption. In February 2018, the FASB issued ASU 2018-02 "Income Statement—Reporting Comprehensive Income (Topic 220)." This update addresses the revaluation of deferred tax assets and liabilities due to the Tax Cuts and Jobs Act of 2017 impacting income from continuing operations, even if the initial income tax effects were recognized in other comprehensive income. The update allows entities to reclassify the tax effects that were originally in other comprehensive income from accumulated other comprehensive income to retained earnings. The update requires entities to disclose whether the election was made and a description of the income tax effects. The update can be: (a) applied to the period of adoption, or (b) applied retrospectively to each period in which the Tax Cuts and Jobs Act of 2017 is in effect. Grace is required to adopt the amendments in this update for fiscal years and interim periods beginning after December 15, 2018, with early adoption permitted. Grace is currently evaluating the timing and effect of adoption. U.S. Tax Reform On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the "Act") was signed into law, making significant changes to the Internal Revenue Code. Changes include a federal corporate tax rate decrease from 35% to 21% for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of foreign earnings. Grace has estimated its provision for income taxes in accordance with the Act and guidance available as of the date of this filing and as a result has recorded $143.0 million as additional income tax expense in the 2017 fourth quarter, the period in which the legislation was enacted. The provisional amount related to the remeasurement of certain deferred tax assets and liabilities, based on the rates at which they are expected to reverse in the future, was $120.1 million . The provisional amounts related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings and the state and foreign taxes on the unremitted earnings were $37.4 million and $4.9 million respectively. Additionally, Grace provisionally released valuation allowances on a portion of its state net operating losses and federal tax credits of $2.0 million and $17.4 million . On December 22, 2017, the SEC issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. In accordance with SAB 118, Grace has determined that the $120.1 million of deferred tax expense recorded in connection with the remeasurement of certain deferred tax assets and liabilities and the $37.4 million of current tax expense recorded in connection with the transition tax on the mandatory deemed repatriation of foreign earnings, as well as the state and foreign taxes on unremitted earnings and the release of the valuation allowances, were provisional amounts and reasonable estimates at December 31, 2017. Additional work is necessary for a more detailed analysis of Grace's deferred tax assets and liabilities and its historical foreign earnings as well as potential correlative adjustments. Any subsequent adjustment to these amounts will be recorded to current tax expense in the 2018 quarter during which the analysis is completed, which is expected to be during the second half of 2018. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Act. Grace has not completed its analysis in order to make a policy decision on accounting for GILTI. See Note 7 for more information related to income taxes and U.S. tax reform.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 : December 31, (In millions) 2017 2016 Raw materials $ 48.8 $ 57.7 In process 33.0 33.4 Finished products 124.7 115.8 Other 24.4 21.1 $ 230.9 $ 228.0

Properties and Equipment

Properties and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Properties and Equipment	December 31, (In millions) 2017 2016 Land $ 14.2 $ 10.0 Buildings 404.5 375.4 Information technology and equipment 136.6 125.3 Machinery, equipment and other 1,571.8 1,445.8 Projects under construction 135.4 100.6 Properties and equipment, gross 2,262.5 2,057.1 Accumulated depreciation and amortization (1,463.4 ) (1,327.5 ) Properties and equipment, net $ 799.1 $ 729.6 Capitalized interest costs amounted to $1.5 million , $1.3 million , and $1.0 million in 2017 , 2016 , and 2015 , respectively. Depreciation and lease amortization expense relating to properties and equipment was $96.1 million , $85.7 million , and $81.8 million in 2017 , 2016 , and 2015 , respectively. Grace's expense for operating leases was $11.3 million , $10.0 million , and $10.6 million in 2017 , 2016 , and 2015 , respectively. At December 31, 2017 , minimum future non-cancelable payments for operating leases are: (In millions) 2018 $ 10.4 2019 7.3 2020 5.5 2021 3.0 2022 2.8 Thereafter 39.3 $ 68.3

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 , are as follows: (In millions) Catalysts Technologies Materials Technologies Total Grace Balance, December 31, 2015 $ 292.7 $ 43.8 $ 336.5 Goodwill acquired during the year 63.8 — 63.8 Foreign currency translation (3.0 ) (0.6 ) (3.6 ) Write-off related to exited product lines — (2.5 ) (2.5 ) Balance, December 31, 2016 353.5 40.7 394.2 Goodwill acquired during the year — 2.4 2.4 Foreign currency translation 4.2 1.6 5.8 Balance, December 31, 2017 $ 357.7 $ 44.7 $ 402.4 Grace's net book value of other intangible assets at December 31, 2017 and 2016 , was $255.4 million and $269.1 million , respectively, detailed as follows: December 31, 2017 December 31, 2016 (In millions) Gross Carrying Amount Accumulated Amortization Gross Carrying Accumulated Technology $ 214.7 $ 41.5 $ 222.3 $ 38.9 Customer lists 55.8 8.8 69.6 20.3 Trademarks 25.5 2.6 25.3 1.5 Other 16.0 3.7 15.7 3.1 Total $ 312.0 $ 56.6 $ 332.9 $ 63.8 Amortization expense related to intangible assets was $15.4 million , $13.9 million , and $16.2 million in 2017 , 2016 , and 2015 , respectively. At December 31, 2017 , estimated future annual amortization expense for intangible assets is: (In millions) 2018 $ 15.4 2019 15.4 2020 15.1 2021 14.9 2022 14.8 Thereafter 179.8 $ 255.4

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Components of Debt December 31, (In millions) 2017 2016 5.125% senior notes due 2021, net of unamortized debt issuance costs of $5.8 at December 31, 2017 (2016—$7.3) $ 694.2 $ 692.7 U.S. dollar term loan, net of unamortized debt issuance costs and discounts of $4.3 at December 31, 2017 (2016—$5.7) 404.1 402.7 5.625% senior notes due 2024, net of unamortized debt issuance costs of $3.5 at December 31, 2017 (2016—$4.0) 296.5 296.0 Euro term loan, net of unamortized debt issuance costs and discounts of $1.0 at December 31, 2017 (2016—$1.3) 94.0 82.5 Debt payable to unconsolidated affiliate 42.4 39.5 Deferred payment obligation — 30.0 Other borrowings(1) 12.7 40.7 Total debt 1,543.9 1,584.1 Less debt payable within one year 20.1 76.5 Debt payable after one year $ 1,523.8 $ 1,507.6 Weighted average interest rates on total debt 4.7 % 4.6 % ___________________________________________________________________________________________________________________ (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, 2017 , were as follows: (In millions) 2018 $ 20.1 2019 8.7 2020 7.4 2021 1,198.2 2022 5.0 Thereafter 304.5 Total debt $ 1,543.9 Credit Agreement On February 3, 2014, Grace entered into a Credit Agreement (the "Credit Agreement") in connection with its exit financing. The Credit Agreement, as amended in connection with the Separation, provides for: (a) a $700 million term loan due in 2021, with interest at LIBOR +200 bps with a 75 bps floor; (b) a €150 million term loan due in 2021, with interest at EURIBOR +225 bps with a 75 bps floor; and (c) a $300 million revolving credit facility due in 2020, with interest at LIBOR +175 bps. The Credit Agreement contains customary affirmative covenants, including but not limited to (i) maintenance of legal existence and compliance with laws and regulations; (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; (vi) transactions with affiliates; and (vii) a maximum total leverage ratio. Grace is in compliance with these covenants. The Credit Agreement contains conditions that would require mandatory principal payments in advance of the term loan maturity date; none of these conditions had been triggered as of December 31, 2017 . 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, the Company has granted security interests in the shares of its Grace–Conn. and Alltech Associates, Inc. subsidiaries, substantially all of its U.S. non-real estate assets and property, and certain U.S. real estate. On January 30, 2015, Grace borrowed on its $250 million delayed draw term loan facility then provided for under the Credit Agreement and used the funds, together with cash on hand, to repurchase the warrant issued to the asbestos personal injury trust (the "PI Trust") for $490 million . (See Note 10 for Chapter 11 information.) Grace had no outstanding draws on its revolving credit facility as of December 31, 2017 ; however, the available credit under that facility was reduced to $262.8 million by outstanding letters of credit. During the 2016 first quarter, in connection with the Separation, GCP distributed $750 million to Grace. Grace used $600 million of those funds to repay $526.9 million of its U.S. dollar term loan, including the $250 million borrowed under the delayed draw facility, and €67.3 million of its euro term loan. As a result, Grace recorded a loss on early extinguishment of $11.1 million , which is included in "other (income) expense" in the Consolidated Statements of Operations. See Note 20 for information related to the Separation. Senior Notes 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"). The net proceeds received from issuance were $985.5 million , a portion of which was used to terminate Grace's obligations under the deferred payment agreement with the PI Trust for $632.0 million and to repay amounts outstanding under Grace's revolving credit facility. The remaining proceeds from the Notes were used to partially fund the settlement of the warrant issued to the PI Trust (as defined in Note 10 ) and for other general corporate purposes. 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. 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 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. This summary of the Credit Agreement, the amendment to the Credit Agreement, the indentures, and the Notes does not purport to be complete and is qualified in its entirety by reference to the full text of such agreements, copies of which have been filed with the SEC.

Fair Value Measurements and Ris

Fair Value Measurements and Risk	12 Months Ended
	Dec. 31, 2017
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, 2017 , the carrying amounts and fair values of Grace's debt were as follows: December 31, 2017 December 31, 2016 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 5.125% senior notes due 2021(1) $ 694.2 $ 728.7 $ 692.7 $ 721.3 U.S. dollar term loan(2) 404.1 409.7 402.7 408.2 5.625% senior notes due 2024(1) 296.5 321.3 296.0 311.5 Euro term loan(2) 94.0 93.7 82.5 82.0 Other borrowings 55.1 55.1 110.2 110.2 Total debt $ 1,543.9 $ 1,608.5 $ 1,584.1 $ 1,633.2 ___________________________________________________________________________________________________________________ (1) Carrying amounts are net of unamortized debt issuance costs of $5.8 million and $3.5 million at December 31, 2017 , and $7.3 million and $4.0 million as of December 31, 2016 , related to the 5.125% senior notes due 2021 and 5.625% senior notes due 2024, respectively. (2) Carrying amounts are net of unamortized debt issuance costs and discounts of $4.3 million and $1.0 million at December 31, 2017 , and $5.7 million and $1.3 million as of December 31, 2016 , related to the U.S. dollar term loan and euro term loan, respectively. At December 31, 2017 , 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 in volatile currencies 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. Excluded components (forward points) on these hedges are amortized to income on a systematic basis. Grace also enters into foreign currency forward contracts to hedge a portion of its net outstanding monetary assets and liabilities. These forward contracts are not designated as hedging instruments under applicable accounting guidance, and therefore all changes in the fair value of the forward contracts are recorded in "other (income) expense, net," in the Consolidated Statements of Operations. These forward contracts 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 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 outstanding at December 31, 2017 , were $230.2 million . 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 its emergence financing, Grace entered into interest rate swaps beginning on February 3, 2015, and maturing on February 3, 2020, fixing the LIBOR component of the interest on $250 million of Grace's term debt at a rate of 2.393% . 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, 2017 and 2016 : Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Currency derivatives $ 3.1 $ — $ 3.1 $ — Total Assets $ 3.1 $ — $ 3.1 $ — Liabilities Currency derivatives $ 23.8 $ — $ 23.8 $ — Interest rate derivatives 1.8 — 1.8 — Total Liabilities $ 25.6 $ — $ 25.6 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Currency derivatives $ 8.8 $ — $ 8.8 $ — Total Assets $ 8.8 $ — $ 8.8 $ — Liabilities Interest rate derivatives $ 6.0 $ — $ 6.0 $ — Currency derivatives 0.9 — 0.9 — Total Liabilities $ 6.9 $ — $ 6.9 $ — The following tables present the location and fair values of derivative instruments included in the Consolidated Balance Sheets as of December 31, 2017 and 2016 : Asset Derivatives Liability Derivatives December 31, 2017 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.7 Other current liabilities $ 1.4 Interest rate contracts Other current assets — Other current liabilities 1.3 Currency contracts Other assets — Other liabilities 22.2 Interest rate contracts Other assets — Other liabilities 0.5 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.4 Other current liabilities 0.2 Total derivatives $ 3.1 $ 25.6 Asset Derivatives Liability Derivatives December 31, 2016 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 4.0 Other current liabilities $ — Interest rate contracts Other current assets — Other current liabilities 2.8 Currency contracts Other assets 4.0 Other liabilities — Interest rate contracts Other assets — Other liabilities 3.2 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.8 Other current liabilities 0.9 Total derivatives $ 8.8 $ 6.9 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, 2017 , 2016 , and 2015 : Year Ended December 31, 2017 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 0.9 Interest expense $ (2.7 ) Currency contracts(1) (3.6 ) Other expense (2.9 ) Total derivatives $ (2.7 ) $ (5.6 ) ___________________________________________________________________________________________________________________ (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, 2016 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (2.2 ) Interest expense $ (4.1 ) Currency contracts (0.1 ) Other expense 0.8 Total derivatives $ (2.3 ) $ (3.3 ) Year Ended December 31, 2015 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (5.6 ) Interest expense $ (3.8 ) Currency contracts 1.4 Other expense 0.7 Total derivatives $ (4.2 ) $ (3.1 ) 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, 2017 2016 2015 (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 $ 79.5 $ (8.4 ) $ 81.5 $ 13.3 $ 99.4 $ (13.8 ) Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Amount of gain or (loss) reclassified from accumulated OCI into income $ (2.7 ) $ — $ (4.1 ) $ — $ (3.8 ) $ — Currency contracts Amount of gain or (loss) reclassified from accumulated OCI into income — (2.9 ) — 0.8 — 0.7 Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 0.6 — — — — Net Investment Hedges Grace uses cross-currency swaps as derivative hedging instruments in certain net investment hedges of its non-U.S. subsidiaries. The effective portion of gains and losses attributable to these net investment hedges is 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. At December 31, 2017 , 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 also uses foreign currency denominated debt and deferred intercompany royalties as non-derivative hedging instruments in certain net investment hedges. The effective portion of gains and losses attributable to these net investment hedges is recorded to "currency translation adjustments" within "accumulated other comprehensive income (loss)." 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. At December 31, 2017 , €80.1 million of Grace's term loan principal was designated as a hedging instrument of its net investment in its European subsidiaries. At December 31, 2017 , €33.7 million of Grace's deferred intercompany royalties was designated as a hedging instrument of its net investment in European subsidiaries. The following tables present the location and amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges for the years ended December 31, 2017 , 2016 , and 2015 . There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented in the tables below. Year Ended December 31, 2017 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ (21.9 ) Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ (11.2 ) Foreign currency denominated deferred intercompany royalties (6.5 ) $ (17.7 ) Year Ended December 31, 2016 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ 5.6 Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ 4.6 Foreign currency denominated deferred intercompany royalties 2.5 $ 7.1 Year Ended December 31, 2015 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ 18.3 Credit Risk Grace is exposed to credit risk in its trade accounts receivable. Customers in the petroleum refining industry represent the greatest exposure. 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, 2017
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 2017 , 2016 , and 2015 are as follows: (In millions) 2017 2016 2015 Income from continuing operations before income taxes: Domestic $ 28.3 $ 72.7 $ 97.1 Foreign 182.6 93.3 96.6 Total $ 210.9 $ 166.0 $ 193.7 Benefit from (provision for) income taxes: Federal—deferred $ (144.6 ) $ (11.8 ) $ (35.4 ) State and local—current 0.2 (0.7 ) 4.1 State and local—deferred (1.7 ) (17.7 ) (6.4 ) Foreign—current (50.8 ) (36.6 ) (23.5 ) Foreign—deferred (3.6 ) 7.8 (8.6 ) Total $ (200.5 ) $ (59.0 ) $ (69.8 ) The difference between the benefit from (provision for) income taxes on continuing operations at the U.S. federal income tax rate of 35% and Grace's overall income tax provision is summarized as follows: (In millions) 2017 2016 2015 Tax provision at U.S. federal income tax rate $ (73.8 ) $ (58.1 ) $ (67.8 ) Change in benefit (provision) resulting from: Provisional charge related to U.S. tax reform (143.0 ) — — Effect of tax rates in foreign jurisdictions 13.3 6.8 3.0 Research and development credit 5.1 — — Stock option exercises 2.8 6.7 — Nontaxable income/non-deductible expenses (2.6 ) (2.5 ) (0.9 ) State and local income taxes, net (1.8 ) (4.7 ) (2.9 ) U.S. tax on foreign earnings (1.2 ) (0.9 ) (1.7 ) Decrease (increase) in valuation allowance (0.3 ) (2.5 ) 1.6 Other 1.0 (3.8 ) (1.1 ) Benefit from (provision for) income taxes $ (200.5 ) $ (59.0 ) $ (69.8 ) Grace has estimated its provision for income taxes in accordance with the Tax Cuts and Jobs Act of 2017 (the "Act") and guidance available as of the date of this filing and as a result has recorded a provisional income tax expense of $143.0 million in the 2017 fourth quarter, the period in which the legislation was enacted. The provisional amount related to the remeasurement of certain deferred tax assets and liabilities, based on the rates at which they are expected to reverse in the future, was $120.1 million . The provisional amounts related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings and the state and foreign taxes on the unremitted earnings were $37.4 million and $4.9 million , respectively. Grace is no longer indefinitely reinvested with respect to its historical unremitted earnings of its foreign subsidiaries. Additionally, Grace provisionally released valuation allowances on a portion of its state net operating losses and federal tax credits of $2.0 million and $17.4 million , respectively. The Act significantly changes how the U.S. taxes corporations. The Act requires complex computations to be performed that were not previously required in U.S. tax law, significant judgments to be made in interpretation of the provisions of the Act and significant estimates in calculations, and the preparation and analysis of information not previously relevant or regularly produced. The U.S. Treasury Department, the IRS, and other standard-setting bodies could interpret or issue guidance on how provisions of the Act will be applied or otherwise administered that is different from Grace's interpretation as of the date of this filing. As Grace completes its analysis of the Act, collects and prepares necessary data including finalizing total post-1986 earnings and profits of its foreign subsidiaries, and interprets any additional guidance, Grace may make adjustments to the provisional amounts that have been recorded that may materially impact its provision for income taxes in the period in which the adjustments are made. Grace expects to complete its analysis of the provisional items during the second half of 2018. Deferred Tax Assets and Liabilities As of December 31, 2017 and 2016 , the tax attributes giving rise to deferred tax assets and liabilities consisted of the following items. December 31, (In millions) 2017 2016 Deferred tax assets: Federal tax credit carryforwards $ 269.6 $ 183.2 Pension liabilities 104.8 120.1 U.S. net operating loss carryforwards 89.5 293.6 State net operating loss carryforwards 58.2 50.9 Research and development 22.8 35.4 Prepaid royalties 21.4 20.8 Liability for environmental remediation 16.4 24.6 Reserves and allowances 15.2 31.1 Foreign net operating loss carryforwards 6.6 5.9 Liability for asbestos-related litigation — 11.1 Other 14.5 29.0 Total deferred tax assets $ 619.0 $ 805.7 Deferred tax liabilities: Properties and equipment $ (32.0 ) $ (38.5 ) Intangible assets (15.1 ) (18.4 ) Pension assets — (6.1 ) Other (11.3 ) (4.7 ) Total deferred tax liabilities $ (58.4 ) $ (67.7 ) Valuation allowance: Federal tax credit carryforwards $ (0.3 ) $ (17.7 ) State net operating loss carryforwards (9.2 ) (11.2 ) Foreign net operating loss carryforwards (2.8 ) (2.5 ) Total valuation allowance (12.3 ) (31.4 ) Net deferred tax assets $ 548.3 $ 706.6 Grace's deferred tax assets decreased by $158.3 million from December 31, 2016 , to December 31, 2017 , largely as a result of the Act. 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. The valuation allowance decreased by $19.1 million from December 31, 2016 , to December 31, 2017 , due to a decrease of $19.4 million related to the impact of the Act offset by an increase of $0.3 million for foreign deferred tax assets. U.S. Federal and State Net Operating Losses and Credit Carryforwards Grace has $269.6 million in federal tax credit carryforwards. In order to fully utilize the credits before they expire from 2021 to 2027 Grace will need to generate domestic and foreign source income of approximately $1.2 billion and approximately $200 million , respectively. Grace has U.S. federal and state net operating losses. The deferred tax asset related to federal NOLs is $89.5 million . In order to fully utilize the NOLs before they expire in 2035, Grace will need to generate approximately $440 million in U.S. taxable income. The deferred tax asset, net of federal benefit, before valuation allowance related to state NOLs is $58.2 million . In order to fully utilize the state NOLs before they expire (from 2018 to 2035), Grace would need to generate approximately $1.5 billion in state taxable income. Unrecognized Tax Benefits The balance of unrecognized tax benefits at December 31, 2017 , was $17.7 million compared with $18.7 million at December 31, 2016 . A rollforward of the unrecognized tax benefits for the three years ended December 31, 2017 , follows. (In millions) Unrecognized Tax Benefits Balance, December 31, 2014 $ 26.5 Additions for current year tax positions 0.1 Additions for prior year tax positions 0.8 Reductions for prior year tax positions and reclassifications (1.6 ) Reductions for expirations of statute of limitations (1.5 ) Settlements (1.2 ) Balance, December 31, 2015 23.1 Additions for current year tax positions 6.8 Additions for prior year tax positions 0.2 Reductions for prior year tax positions and reclassifications (0.2 ) Settlements (3.3 ) Transferred to GCP upon Separation (7.9 ) Balance, December 31, 2016 18.7 Additions for current year tax positions 0.8 Additions for prior year tax positions 0.7 Reductions for prior year tax positions and reclassifications (2.5 ) Balance, December 31, 2017 $ 17.7 The entire balance of unrecognized tax benefits as of December 31, 2017 , of $17.7 million , if recognized, would reduce the effective tax rate. The balance of unrecognized tax benefits as of December 31, 2017 , includes $17.7 million for tax positions with an indirect tax benefit that results in a corresponding deferred tax asset as of December 31, 2017 . 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. There were no interest and penalties accrued on unrecognized tax benefits as of December 31, 2017 and 2016 . Grace files U.S. federal income tax returns as well as income tax returns in various state and foreign jurisdictions. Grace's unrecognized tax benefits are related to income tax returns for tax years that remain subject to examination by the relevant taxing authorities. The following table summarizes these open tax years by major jurisdiction: Tax Jurisdiction(1) Examination in Progress Examination Not Initiated United States—Federal 2007, 2009 2010-2016 United States—States 2010-2014 2015-2016 Germany 2014-2016 None Sweden None 2013-2016 ___________________________________________________________________________________________________________________ (1) Includes federal, state, provincial or local jurisdictions, as applicable. Grace notes that there are 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. As a multinational taxpayer, Grace is under continual audit by various tax authorities. Grace believes that the amount of the liability for unrecognized tax benefits will be unchanged in the next 12 months.

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefit Plans	12 Months Ended
	Dec. 31, 2017
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 underfunded and unfunded pension plans: December 31, (In millions) 2017 2016 Underfunded defined benefit pension plans $ (110.5 ) $ (83.1 ) Unfunded defined benefit pension plans (391.9 ) (341.2 ) Total underfunded and unfunded defined benefit pension plans (502.4 ) (424.3 ) Pension liabilities included in other current liabilities (15.0 ) (14.4 ) Net funded status $ (517.4 ) $ (438.7 ) Underfunded plans include a group of advance-funded plans that are underfunded on a projected benefit obligation ("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 is closed to new entrants after January 1, 2017. U.S. salaried employees and certain U.S. hourly employees hired on or after January 1, 2017, and employees in Germany hired on or after January 1, 2016, will participate in defined contribution plans instead of defined benefit pension plans. 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, 2017 , measurement date for Grace's defined benefit pension plans, the PBO was $1,648.7 million as measured under U.S. GAAP compared with $1,543.3 million as of December 31, 2016 . The PBO basis reflects the present value (using a 3.57% weighted average discount rate for U.S. plans and a 1.84% weighted average discount rate for non-U.S. plans as of December 31, 2017 ) 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 the plan and use participant-specific information as well as certain key assumptions provided by management. Defined Contribution Retirement Plan 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 $11.5 million , $11.1 million , and $10.4 million for the years ended December 31, 2017 , 2016 , and 2015 , 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 2017 and 2016 : Defined Benefit Pension Plans (In millions) U.S. Non-U.S. Total 2017 2016 2017 2016 2017 2016 Change in Projected Benefit Obligation (PBO): Benefit obligation at beginning of year $ 1,274.2 $ 1,238.8 $ 269.1 $ 238.8 $ 1,543.3 $ 1,477.6 Service cost 17.1 17.8 8.4 6.8 25.5 24.6 Interest cost 42.0 40.5 4.4 5.1 46.4 45.6 Amendments — (1.3 ) — — — (1.3 ) Settlements/curtailments — — — (2.3 ) — (2.3 ) Acquisitions — — 0.4 — 0.4 — Actuarial (gain) loss 88.3 62.3 13.4 39.9 101.7 102.2 Benefits paid (91.2 ) (83.9 ) (7.8 ) (7.5 ) (99.0 ) (91.4 ) Currency exchange translation adjustments — — 35.2 (11.7 ) 35.2 (11.7 ) Other (4.8 ) — — — (4.8 ) — Benefit obligation at end of year $ 1,325.6 $ 1,274.2 $ 323.1 $ 269.1 $ 1,648.7 $ 1,543.3 Change in Plan Assets: Fair value of plan assets at beginning of year $ 1,086.4 $ 1,067.2 $ 18.2 $ 18.7 $ 1,104.6 $ 1,085.9 Actual return on plan assets 112.7 95.6 1.6 (0.5 ) 114.3 95.1 Employer contributions 9.6 7.5 8.2 8.4 17.8 15.9 Settlements — — — (1.3 ) — (1.3 ) Benefits paid (91.2 ) (83.9 ) (7.8 ) (7.5 ) (99.0 ) (91.4 ) Currency exchange translation adjustments — — 1.3 0.4 1.3 0.4 Other (7.7 ) — — — (7.7 ) — Fair value of plan assets at end of year $ 1,109.8 $ 1,086.4 $ 21.5 $ 18.2 $ 1,131.3 $ 1,104.6 Funded status at end of year (PBO basis) $ (215.8 ) $ (187.8 ) $ (301.6 ) $ (250.9 ) $ (517.4 ) $ (438.7 ) Amounts recognized in the Consolidated Balance Sheets consist of: Current liabilities $ (7.0 ) $ (7.4 ) $ (8.0 ) $ (7.0 ) $ (15.0 ) $ (14.4 ) Noncurrent liabilities (208.8 ) (180.4 ) (293.6 ) (243.9 ) (502.4 ) (424.3 ) Net amount recognized $ (215.8 ) $ (187.8 ) $ (301.6 ) $ (250.9 ) $ (517.4 ) $ (438.7 ) Amounts recognized in Accumulated Other Comprehensive (Income) Loss consist of: Prior service credit $ (3.9 ) $ (4.3 ) $ (0.1 ) $ (0.1 ) $ (4.0 ) $ (4.4 ) Net amount recognized $ (3.9 ) $ (4.3 ) $ (0.1 ) $ (0.1 ) $ (4.0 ) $ (4.4 ) Defined Benefit Pension Plans (In millions) U.S. Non-U.S. 2017 2016 2017 2016 Weighted Average Assumptions Used to Determine Benefit Obligations as of December 31: Discount rate 3.57 % 4.06 % 1.84 % 1.91 % Rate of compensation increase 4.10 % 4.10 % 2.64 % 3.09 % Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended December 31: Discount rate for determining service cost 4.41 % 4.68 % 2.09 % 2.90 % Discount rate for determining interest cost 3.42 % 3.38 % 1.69 % 2.26 % Expected return on plan assets 5.50 % 5.50 % 4.69 % 5.08 % Rate of compensation increase 4.10 % 4.10 % 3.09 % 3.09 % The following table presents the components of net periodic benefit cost (income) and other amounts recognized in "other comprehensive (income) loss." 2017 2016 2015 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Net Periodic Benefit Cost (Income) Service cost $ 17.1 $ 8.4 $ 17.8 $ 6.8 $ 25.7 $ 11.7 Interest cost 42.0 4.4 40.5 5.1 55.1 16.1 Expected return on plan assets (57.5 ) (0.9 ) (56.7 ) (1.0 ) (70.4 ) (13.0 ) Amortization of prior service cost (credit) (0.4 ) — (0.2 ) — 0.3 — Annual mark-to-market adjustment 36.0 13.2 23.3 40.1 42.0 (0.1 ) Net curtailment and settlement gain — — — (1.0 ) — — Net periodic benefit cost (income) 37.2 25.1 24.7 50.0 52.7 14.7 Less: discontinued operations — — — — (4.0 ) (16.8 ) Net periodic benefit cost (income) from continuing operations $ 37.2 $ 25.1 $ 24.7 $ 50.0 $ 48.7 $ (2.1 ) Other Changes in Plan Assets and Benefit Obligations Recognized in OCI Net prior service credit $ — $ — $ (1.3 ) $ — $ (3.6 ) $ — Amortization of prior service cost (credit) 0.4 — 0.2 — (0.3 ) — Total recognized in OCI 0.4 — (1.1 ) — (3.9 ) — Total recognized in net periodic benefit cost (income) and OCI $ 37.6 $ 25.1 $ 23.6 $ 50.0 $ 44.8 $ (2.1 ) The estimated prior service credit for the defined benefit pension plans that will be amortized from "accumulated other comprehensive (income) loss" into net periodic benefit cost (income) over the next fiscal year is $0.6 million . The estimated net deferred actuarial loss and prior service credit for the other postretirement plan that will be amortized from "accumulated other comprehensive (income) loss" into net periodic benefit cost (income) over the next fiscal year are $0.4 million and $1.0 million , respectively. Funded Status of U.S. Pension Plans (In millions) Underfunded U.S. Qualified Pension Plans(1) Unfunded Pay-As-You-Go U.S. Nonqualified Plans(2) 2017 2016 2017 2016 Projected benefit obligation $ 1,217.1 $ 1,167.9 $ 108.5 $ 106.3 Fair value of plan assets 1,109.8 1,086.4 — — Funded status (PBO basis) $ (107.3 ) $ (81.5 ) $ (108.5 ) $ (106.3 ) Funded Status of Non-U.S. Pension Plans (In millions) Underfunded Non-U.S. Pension Plans(1) Unfunded Pay-As-You-Go Non-U.S. Pension Plans(2) 2017 2016 2017 2016 Projected benefit obligation $ 24.7 $ 19.8 $ 298.4 $ 249.3 Fair value of plan assets 21.5 18.2 — — Funded status (PBO basis) $ (3.2 ) $ (1.6 ) $ (298.4 ) $ (249.3 ) ___________________________________________________________________________________________________________________ (1) Plans intended to be advance-funded. (2) Plans intended to be pay-as-you-go. The accumulated benefit obligation for all defined benefit pension plans was approximately $1,570 million and $1,478 million as of December 31, 2017 and 2016 , respectively. Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation (In millions) U.S. Non-U.S. Total 2017 2016 2017 2016 2017 2016 Projected benefit obligation $ 1,325.6 $ 1,274.2 $ 298.4 $ 249.3 $ 1,624.0 $ 1,523.5 Accumulated benefit obligation 1,286.0 1,238.8 263.6 222.6 1,549.6 1,461.4 Fair value of plan assets 1,109.8 1,086.4 — — 1,109.8 1,086.4 Estimated Expected Future Benefit Payments Reflecting Future Service for the Fiscal Years Ending (In millions) Pension Plans Total Payments U.S. Non-U.S.(1) Benefit Payments Benefit Payments 2018 $ 82.9 $ 8.9 $ 91.8 2019 83.1 8.4 91.5 2020 83.3 8.6 91.9 2021 83.4 8.9 92.3 2022 83.7 9.1 92.8 2023 - 2027 413.2 49.0 462.2 ___________________________________________________________________________________________________________________ (1) Non-U.S. estimated benefit payments for 2018 and future periods have been translated at the applicable December 31, 2017 , 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 3.57% as of December 31, 2017 , 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, 2017 and 2016 , the German pension plans represented approximately 91% and 92% , respectively, of the benefit obligation of the non-U.S. pension plans. The assumed weighted average discount rate as of December 31, 2017 , for Germany ( 1.73% ) 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. As of December 31, 2015, Grace changed the approach used to determine the service and interest cost components of defined benefit pension expense. Previously, Grace estimated service and interest costs using a single weighted average discount rate derived from the same yield curve used to measure the projected benefit obligation. For 2016 and 2017, Grace elected to measure service and interest costs by applying the specific spot rates along that yield curve to the plans’ liability cash flows. Grace believes the new approach provides a more precise measurement of service and interest costs by aligning the timing of the plans’ liability cash flows to the corresponding spot rates on the yield curve. This change did not affect the measurement of the projected benefit obligation as of December 31, 2015. Grace considers this a change in accounting estimate, which is being accounted for prospectively as of January 1, 2016. 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. • Growth 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. • U.S. equity securities: the portfolio contains domestic equities that are passively managed to the S&P 500 and Russell 2000 benchmarks and an allocation to an active portfolio benchmarked to the Russell Mid-Cap and Russell 2000 indices. • Non-U.S. equity securities: the portfolio contains non-U.S. equities in an actively managed strategy benchmarked to the MSCI ACWI ex US index. Currency futures and forward contracts may be held for the sole purpose of hedging existing currency risk in the portfolio. • Other investments: may include (a) high yield bonds: fixed income portfolio of securities below investment grade including up to 30% of the portfolio in non-U.S. issuers; and (b) global real estate securities: portfolio of diversified REIT and other liquid real estate related securities. These portfolios combine income generation and capital appreciation opportunities from developed markets globally. • Liquidity portfolio: invested in short-term assets intended to pay periodic plan benefits and expenses. For 2017 , the expected long-term rate of return on assets for the U.S. qualified pension plans was 5.50% . Average annual returns over one-, three-, five-, and ten-year periods were approximately 11% , 6% , 6% , and 5% , respectively. The expected return on plan assets for the U.S. qualified pension plans for 2017 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, 2017 , and the actual allocation at December 31, 2017 and 2016 , for Grace's U.S. qualified pension plans are as follows: Target Allocation Percentage of Plan Assets December 31, U.S. Qualified Pension Plans Asset Category 2017 2017 2016 U.S. equity securities 10 % 11 % 8 % Non-U.S. equity securities 5 % 5 % 6 % Short-term debt securities 10 % 10 % 4 % Intermediate-term debt securities 32 % 32 % 32 % Long-term debt securities 41 % 40 % 48 % Other investments 2 % 2 % 2 % 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, 2017 and 2016 . Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) U.S. equity group trust funds $ 118.8 $ — $ 118.8 $ — Non-U.S. equity group trust funds 56.8 — 56.8 — Corporate and government bond group trust funds—intermediate-term 353.6 — 353.6 — Corporate and government bond group trust funds—long-term 443.4 — 443.4 — Other fixed income group trust funds 25.3 — 25.3 — Common/collective trust funds 92.9 — 92.9 — Annuity and immediate participation contracts 19.0 — 19.0 — Total Assets $ 1,109.8 $ — $ 1,109.8 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) U.S. equity group trust funds $ 91.5 $ — $ 91.5 $ — Non-U.S. equity group trust funds 62.6 — 62.6 — Corporate bond group trust funds—intermediate-term 342.6 — 342.6 — Corporate bond group trust funds—long-term 521.5 — 521.5 — Other fixed income group trust funds 22.4 — 22.4 — Common/collective trust funds 27.4 — 27.4 — Annuity and immediate participation contracts 18.4 — 18.4 — Total Assets $ 1,086.4 $ — $ 1,086.4 $ — Non-U.S. pension plans accounted for approximately 2% of total global pension assets at December 31, 2017 and 2016 . 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 97% of the total non-U.S. pension plan assets at December 31, 2017 and 2016 . The expected long-term rate of return on assets for the Canadian pension plan was 4.75% for 2017 . The target allocation of investment assets at December 31, 2017 , and the actual allocation at December 31, 2017 and 2016 , for the Canadian pension plan are as follows: Target Allocation Percentage of Plan Assets December 31, Canadian Pension Plan Asset Category 2017 2017 2016 Equity securities 28 % 28 % 28 % Bonds 58 % 58 % 57 % Other investments 14 % 14 % 15 % Total 100 % 100 % 100 % The plan assets of the other country plans represent approximately 3% in the aggregate of total non-U.S. pension plan assets at December 31, 2017 and 2016 . The following table presents the fair value hierarchy for the non-U.S. pension plan assets measured at fair value as of December 31, 2017 and 2016 . Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Common/collective trust funds $ 20.7 $ — $ 20.7 $ — Corporate bonds 0.4 — 0.4 — Insurance contracts and other investments 0.4 — 0.4 — Total Assets $ 21.5 $ — $ 21.5 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Common/collective trust funds $ 17.6 $ — $ 17.6 $ — Corporate bonds 0.3 — 0.3 — Insurance contracts and other investments 0.3 — 0.3 — Total Assets $ 18.2 $ — $ 18.2 $ — 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, 2017 , there are no minimum required payments under ERISA for 2018 . Grace intends to fund non-U.S. pension plans based on applicable legal requirements and actuarial and trustee recommendations. Grace expects to contribute approximately $9 million to its non-U.S. pension plans in 2018 .

Other Balance Sheet Accounts

Other Balance Sheet Accounts	12 Months Ended
	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Other Balance Sheet Accounts	December 31, (In millions) 2017 2016 Other Current Liabilities Accrued compensation $ 60.7 $ 49.6 Environmental contingencies 23.5 32.5 Deferred revenue 19.5 27.2 Accrued interest 16.5 16.2 Pension liabilities 15.0 14.4 Income taxes payable 12.2 5.7 Other accrued liabilities 70.4 63.3 $ 217.8 $ 208.9 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) 2017 2016 Other Liabilities Environmental contingencies $ 46.8 $ 33.8 Liability to unconsolidated affiliate 32.7 27.0 Fair value of currency and interest rate contracts 22.7 3.2 Deferred revenue 14.9 2.3 Asset retirement obligation 10.4 10.2 Deferred income taxes 8.2 2.8 Postemployment liability 5.2 7.2 Other noncurrent liabilities 28.4 40.2 $ 169.3 $ 126.7

Commitments and Contingent Liab

Commitments and Contingent Liabilities	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Over the years, Grace operated numerous types of businesses that are no longer part of its business portfolio. As Grace divested or otherwise ceased operating these businesses, it retained certain liabilities and obligations, which we refer to as legacy liabilities. The principal legacy liabilities are product and environmental liabilities. Although the outcome of each of the matters discussed below cannot be predicted with certainty, Grace has assessed its risk and has made accounting estimates as required under U.S. GAAP. Legacy Product and Environmental Liabilities 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 installed in the U.S. ("ZAI PD Claims"), the PD Trust was funded with $34.4 million on the Effective Date and $30.0 million on February 3, 2017. Grace is also obligated to make up to 10 contingent deferred payments of $8 million per year to the PD Trust in respect of ZAI PD Claims during the 20 -year period beginning on the fifth anniversary of the Effective Date, 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. Grace has not accrued for the 10 additional payments as Grace does not currently believe they are probable. Grace is not obligated to make additional payments to the PD Trust in respect of ZAI PD Claims beyond the payments described above. Grace has satisfied all of its financial obligations with respect to Canadian ZAI PD Claims. 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. 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. 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, 2017 , Grace's estimated liability for legacy environmental response costs totaled $70.3 million compared with $66.3 million at December 31, 2016 , 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 exists, yet there is sufficient information to estimate response costs. Grace recorded pre-tax charges of $24.4 million , $29.2 million , and $6.4 million for legacy environmental matters in 2017 , 2016 , and 2015 , respectively, which is included in "provision for environmental remediation" 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. In its 2017 Annual Project Update for the Libby Asbestos Superfund Site, the EPA announced a narrowing of its focus from the former "OU3 Study Area" to a smaller Operable Unit 3 ("OU3"). Within this revised area, the RI/FS will determine the specific areas 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. Based on communications from regulatory agencies, Grace expects the RI/FS and a record of decision to be completed by the end of 2019. When meaningful new information becomes available, Grace will reevaluate estimated liability for the costs for remediation of the mine and surrounding area and adjust its reserves accordingly. The EPA is also investigating or remediating formerly owned or operated sites that processed Libby vermiculite into finished products. Grace is cooperating with the EPA on these investigation and remediation activities and has recorded a liability to the extent that its review has indicated that a probable liability has been incurred and the cost is estimable. These liabilities cover the estimated cost of investigations and, to the extent an assessment has indicated that remediation is necessary, the estimated cost of response actions. Response actions typically involve soil excavation and removal, and replacement with clean fill. The EPA may commence additional investigations in the future at other sites that processed Libby vermiculite, but Grace does not believe, based on its knowledge of prior and current operations and site conditions, that liability for remediation at such other sites is probable. Grace accrued $9.5 million , $24.8 million , and $6.0 million in 2017 , 2016 , and 2015 , respectively, for future costs related to vermiculite-related matters. More than half of the 2016 amount was for the completion of the RI/FS of the Libby mine and surrounding area, which is expected to be spent over the next two years. Grace's total estimated liability for response costs that are currently estimable for the Libby mine and surrounding area, and at vermiculite processing sites outside of Libby at December 31, 2017 and 2016 , was $25.8 million and $31.2 million , respectively. It is probable that Grace's ultimate liability for these vermiculite-related matters will exceed current estimates by material amounts. Non-Vermiculite-Related Matters During 2017, Grace accrued $14.9 million to increase non-vermiculite environmental reserves. This included a $5.9 million increase to an existing reserve based on refinement of a scope of work for remediation of materials related to a legacy business located at a current manufacturing site, as well as $7.2 million to increase the liability for remediation at a former manufacturing site to maintain ten years of operation and maintenance expenses. At December 31, 2017 and 2016 , Grace's estimated legacy environmental liability for response costs at sites not related to its former vermiculite mining and processing activities was $44.5 million and $35.1 million , respectively. 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. 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 of a former business unit or product line in which Grace has agreed to indemnify the buyer against liabilities related to activities prior to the closing of the transaction, including environmental liabilities. • Contracts related to the Separation in which Grace has agreed to indemnify GCP against liabilities related to activities prior to the closing of the transaction, including tax, employee, and environmental liabilities. • 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, 2017 , Grace had gross financial assurances issued and outstanding of $124.6 million , composed of $39.5 million of surety bonds issued by various insurance companies and $85.1 million of standby letters of credit and other financial assurances issued by various banks. In November 2017, an additional $ 28.3 million in performance and warranty bonds were issued. These bonds were not released to the beneficiary until 2018 and are not included above.

Restructuring Expenses and Rela

Restructuring Expenses and Related Asset Impairments	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring Expenses and Related Asset Impairments	Restructuring Expenses In 2017 , 2016 , and 2015 , Grace incurred costs from restructuring actions, primarily related to workforce reductions as a result of changes in the business environment and its business structure, which are included in "restructuring and repositioning expenses" in the Consolidated Statements of Operations. Restructuring costs in 2017 primarily related to workforce reduction programs in Manufacturing, Supply Chain, Finance and IT. Costs in 2016 primarily related to the exit of certain non-strategic product lines in the Materials Technologies reportable segment in the 2016 first half. Costs in 2015 were in part due to the Separation. The following table presents restructuring expenses by reportable segment for the years ended December 31, 2017 , 2016 , and 2015 . Year Ended December 31, (In millions) 2017 2016 2015 Catalysts Technologies $ 3.7 $ 3.4 $ 4.8 Materials Technologies (0.1 ) 15.1 0.8 Corporate 7.9 5.8 5.7 Total restructuring expenses $ 11.5 $ 24.3 $ 11.3 These costs are not included in segment operating income. Substantially all costs related to the restructuring programs are expected to be paid by December 31, 2018. The following table presents components of the change in restructuring liability for the years ended December 31, 2017 , 2016 , and 2015 : (In millions) Total Balance, December 31, 2014 $ 2.1 Accruals for severance and other costs 11.3 Payments (5.6 ) Currency translation adjustments and other (0.2 ) Balance, December 31, 2015 $ 7.6 Accruals for severance and other costs 17.8 Payments (16.0 ) Currency translation adjustments and other 0.2 Balance, December 31, 2016 $ 9.6 Accruals for severance and other costs 11.4 Payments (14.4 ) Currency translation adjustments and other 0.1 Balance, December 31, 2017 $ 6.7 Repositioning Expenses Repositioning expenses primarily include third party costs related to transformative productivity programs and costs incurred to complete the Separation. Pretax repositioning expenses included in continuing operations for the years ended December 31, 2017 , 2016 , and 2015 were $15.2 million , $14.3 million , and $9.1 million respectively. Expenses incurred in 2017 primarily related to third-party costs associated with productivity and transformation initiatives, as well as costs related to the Separation. Expenses incurred in 2016 and 2015 primarily related to the Separation. Substantially all of these costs have been or are expected to be settled in cash. In 2017, Grace initiated a multi-year program to transform its manufacturing and business processes to extend its competitive advantages and improve its cost position. Grace expects to significantly improve its manufacturing performance, reduce its manufacturing costs, and improve its demand and supply planning capabilities. Grace also expects to invest significant capital in its manufacturing plants to accelerate growth and improve performance.

Other Expense, net

Other Expense, net	12 Months Ended
	Dec. 31, 2017
Other Income and Expenses [Abstract]
Other (Income) Expense, net	Components of other (income) expense, net are as follows: Year Ended December 31, (In millions) 2017 2016 2015 Business interruption insurance recoveries $ (26.6 ) $ — $ — Accounts receivable reserve—Venezuela 10.0 — — Currency transaction effects 5.0 (1.0 ) (1.5 ) Third-party acquisition-related costs 2.9 2.5 — Net (gain) loss on sales of investments and disposals of assets 1.6 (1.4 ) (10.6 ) Chapter 11 expenses, net 1.4 3.4 5.1 Loss on early extinguishment of debt — 11.1 — Other miscellaneous expense (income) (2.7 ) (1.3 ) (6.8 ) Total other (income) expense, net $ (8.4 ) $ 13.3 $ (13.8 ) In January 2017, a Catalysts Technologies customer experienced an explosion and fire resulting in an extended outage. Grace received $25.0 million in payments from its third-party insurer in 2017, under its business interruption insurance policy for a portion of profits lost as a result of the outage. The policy had a $25 million limit for this event. During the 2017 third quarter, Grace recorded a $10.0 million charge to fully reserve for a trade receivable from a Venezuela-based customer related to increased economic uncertainty and the recent political unrest and sanctions. See Note 5 for more information related to Grace's 2016 early extinguishment of debt.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 , and 2015 : Year Ended December 31, 2017 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (2.3 ) $ 0.8 $ (1.5 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.4 (0.1 ) 0.3 Net deferred actuarial gain (loss) arising during period (0.1 ) — (0.1 ) Benefit plans, net (2.0 ) 0.7 (1.3 ) Currency translation adjustments(1) (23.1 ) (2.9 ) (26.0 ) Gain (loss) from hedging activities 2.9 (2.1 ) 0.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (22.2 ) $ (4.3 ) $ (26.5 ) ___________________________________________________________________________________________________________________ (1) In the 2017 third quarter, Grace recorded an out-of-period adjustment to recognize the accumulated deferred tax liability for its euro loan net investment hedge (see Note 6). The correction resulted in a reduction in deferred tax assets and a charge to "other comprehensive income (loss)" of $16.9 million . Grace has assessed the impact of this error and concluded that it was not material to any prior-period and the impact of correcting the error in 2017 is not material. Year Ended December 31, 2016 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (2.4 ) $ 0.9 $ (1.5 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.5 (0.2 ) 0.3 Net prior service credit arising during period 1.4 (0.5 ) 0.9 Loss on curtailment of postretirement plans (0.5 ) 0.2 (0.3 ) Benefit plans, net (1.0 ) 0.4 (0.6 ) Currency translation adjustments (1.8 ) — (1.8 ) Gain (loss) from hedging activities 0.6 (0.3 ) 0.3 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (2.2 ) $ 0.1 $ (2.1 ) Year Ended December 31, 2015 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (3.1 ) $ 1.0 $ (2.1 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.7 (0.2 ) 0.5 Net prior service credit arising during period 5.7 (1.9 ) 3.8 Net deferred actuarial gain (loss) arising during period (0.4 ) 0.1 (0.3 ) Loss on curtailment of postretirement plans (4.5 ) 1.6 (2.9 ) Benefit plans, net (1.6 ) 0.6 (1.0 ) Currency translation adjustments (43.3 ) — (43.3 ) Gain (loss) from hedging activities 2.1 (0.8 ) 1.3 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (42.8 ) $ (0.2 ) $ (43.0 ) The following table presents the changes in accumulated other comprehensive income (loss), net of tax, for the years ended December 31, 2017 , 2016 , and 2015 : Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Balance, December 31, 2014 $ 4.0 $ (22.8 ) $ (5.0 ) $ (23.8 ) Other comprehensive income (loss) before reclassifications 3.5 (43.3 ) 0.6 (39.2 ) Amounts reclassified from accumulated other comprehensive income (loss) (4.5 ) — 0.7 (3.8 ) Net current-period other comprehensive income (loss) (1.0 ) (43.3 ) 1.3 (43.0 ) Balance, December 31, 2015 $ 3.0 $ (66.1 ) $ (3.7 ) $ (66.8 ) Other comprehensive income (loss) before reclassifications 0.9 (1.8 ) (1.8 ) (2.7 ) Amounts reclassified from accumulated other comprehensive income (loss) (1.5 ) — 2.1 0.6 Net current-period other comprehensive income (loss) (0.6 ) (1.8 ) 0.3 (2.1 ) Distribution of GCP (0.2 ) 135.5 — 135.3 Balance, December 31, 2016 $ 2.2 $ 67.6 $ (3.4 ) $ 66.4 Other comprehensive income (loss) before reclassifications (0.1 ) (26.0 ) (2.7 ) (28.8 ) Amounts reclassified from accumulated other comprehensive income (loss) (1.2 ) — 3.5 2.3 Net current-period other comprehensive income (loss) (1.3 ) (26.0 ) 0.8 (26.5 ) Balance, December 31, 2017 $ 0.9 $ 41.6 $ (2.6 ) $ 39.9 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. See Note 6 for a discussion of hedging activities. See Note 8 for a discussion of pension plans and other postretirement benefit plans.

Shareholders' Equity (Deficit)

Shareholders' Equity (Deficit)	12 Months Ended
	Dec. 31, 2017
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, 2017 , the W. R. Grace & Co. 2014 Stock Incentive Plan (together with the 2011 Stock Incentive Plan and the Amended and Restated 2011 Stock Incentive Plan, collectively, the "Stock Incentive Plans") had 2,219,234 shares of unissued stock reserved for issuance in the event of the exercise of stock options or settlement of stock-based awards. Shares issuable upon the exercise of stock options or the settlement of stock based awards are covered by reissuing treasury stock, to the extent available; otherwise they are covered through newly issued shares. For the years ended December 31, 2017 , 2016 , and 2015 , 386,300 , 745,938 , and 728,408 stock options were exercised for aggregate proceeds of $16.4 million , $17.0 million , and $26.9 million , respectively. Additionally in 2017 , 10,507 common shares were issued to members of the Board of Directors, in payment of their annual retainer; 8,215 shares were issued through net share settlement; 24,432 shares were issued to settle the 2014 Restricted Stock Units (RSUs); and 6,743 shares were issued to settle tranche 1 of the 2016 RSUs. The following table sets forth information relating to common stock activity for the years ended December 31, 2017 , 2016 , and 2015 : Balance of outstanding shares, December 31, 2014 72,922,565 Stock options exercised 728,408 Shares issued 9,378 Shares forfeited (3,120 ) Shares repurchased (3,123,716 ) Balance of outstanding shares, December 31, 2015 70,533,515 Stock options exercised 745,938 Shares issued 110,953 Shares forfeited (305,678 ) Shares repurchased (2,775,297 ) Balance of outstanding shares, December 31, 2016 68,309,431 Stock options exercised 386,300 Shares issued 49,897 Shares forfeited through net share exercise (29,783 ) Shares repurchased (935,435 ) Balance of outstanding shares, December 31, 2017 67,780,410

Stock Incentive Plans

Stock Incentive Plans	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Incentive Plans	The Company has granted nonstatutory stock options to certain key employees under the Stock Incentive Plans. The Stock Incentive Plans are administered by the Compensation Committee of the Board of Directors. 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 August 2022. Previously outstanding stock-based compensation awards granted under equity compensation programs prior to the Separation and held by certain executives and employees were adjusted in 2016 to reflect the impact of the Separation on these awards. To preserve the aggregate intrinsic value of awards held prior to the Separation, as measured immediately before and immediately after the Separation, each holder of stock-based compensation awards generally received an adjusted award consisting of either (i) both a stock-based compensation award denominated in Company equity as it existed subsequent to the Separation and a stock-based compensation award denominated in GCP equity or (ii) solely a stock-based compensation award denominated in Company equity. In the Separation, the determination as to which type of adjustment applied to a holder’s previously outstanding award was based upon the date on which the award was originally granted under the equity compensation programs prior to the Separation. The adjustment of the original awards resulted in $0.6 million of incremental compensation cost in 2016. The following table sets forth information relating to such options during 2017 , 2016 , and 2015 . Stock Option Activity Number Of Shares Average Exercise Price Weighted- Average Grant Date Fair Value Balance, December 31, 2014 2,523,790 $ 55.77 Options exercised (728,408 ) 36.85 Options forfeited (25,000 ) 92.57 Options terminated (500 ) 100.29 Options granted 550,805 77.31 $ 19.28 Balance, December 31, 2015 2,320,687 71.01 Options exercised (745,938 ) 36.97 Options forfeited (9,458 ) 73.40 Options terminated (2,426 ) 67.06 Options granted 377,920 68.32 12.90 Balance, December 31, 2016 1,940,785 66.83 Options exercised (386,300 ) 45.21 Options forfeited (34,545 ) 72.97 Options terminated (23,320 ) 75.60 Options granted 316,830 71.37 13.00 Balance, December 31, 2017 1,813,450 The following is a summary of nonvested option activity for the year ended December 31, 2017 . Stock Option Activity Number Of Shares Weighted- Average Grant Date Fair Value Nonvested options outstanding at beginning of year 878,031 $ 17.76 Granted 316,830 13.00 Vested (417,969 ) 18.78 Forfeited (57,865 ) 18.09 Nonvested options outstanding at end of year 719,027 As of December 31, 2017 , the intrinsic value (the difference between the exercise price and the market price) for options outstanding was $2.8 million and for options exercisable was $2.3 million . The total intrinsic value of all options exercised during the years ended December 31, 2017 , 2016 and 2015 was $10.3 million , $25.9 million and $46.1 million , respectively. A summary of our stock options outstanding and exercisable at December 31, 2017 , follows: Exercise Price Range Number Outstanding Number Exercisable Outstanding Weighted- Average Remaining Contractual Life (Years) Exercisable Weighted- Average Exercise Price $60 - $70 586,054 350,469 2.02 63.90 $70 - $80 1,200,806 724,000 2.48 75.97 $80 - $90 26,590 19,954 1.16 80.76 1,813,450 1,094,423 At December 31, 2017 , the weighted-average remaining contractual term of all options outstanding and exercisable was 2.31 years. Options Granted The Company granted approximately 0.3 million , 0.4 million , and 0.6 million nonstatutory stock options in 2017 , 2016 , and 2015 , respectively, under the Stock Incentive Plans. For the years ended December 31, 2017 , 2016 and 2015 , the Company recognized non-cash stock-based compensation expense of $4.3 million , $6.0 million and $9.9 million , respectively, which is included in "selling, general and administrative expenses" in the Consolidated Statements of Operations. The actual tax benefit realized from stock options exercised totaled $7.4 million , $11.2 million , and $3.3 million for the year ended December 31, 2017 , 2016 and 2015 , 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 both actual stock volatility and the volatility of an industry peer group. The Company believes its actual stock volatility was not representative of future volatility during the time it was in Chapter 11. The following summarizes the assumptions used for estimating the fair value of stock options granted during 2017 , 2016 and 2015 , respectively. 2017 2016 2015 Expected volatility 24.7% - 25.1% 26.2% - 27.5% 23.0% - 27.2% Weighted average expected volatility 24.9% 26.6% 24.5% Expected term 3.00 - 4.00 years 3.00 - 4.00 years 3.00 - 4.00 years Risk-free rate 1.66% 1.01% 1.30% Dividend yield 1.2% 1.0% —% Total unrecognized stock-based compensation expense at December 31, 2017 , was $2.9 million and the weighted-average period over which this expense will be recognized is 0.9 year. Restricted Stock and Performance Based Units During 2017 the Company granted 57,600 RSUs and 115,158 Performance Based Units (PBUs) under the Company's Long-term Incentive Plan (LTIP). During 2016 the Company granted 77,358 RSUs and 124,952 PBUs under the LTIP. During 2015 the Company granted 123,846 RSUs and 1,864 PBUs under the LTIP. During 2017 , 2016 , and 2015 , awards covering 16,395 , 15,197 , and 10,641 shares were forfeited, respectively. The PBUs cliff vest after the completion of the performance periods ending December 31, 2019 and 2018, and have a weighted average grant date fair value of $71.37 and $68.50 , respectively. The RSUs granted in 2017 and 2016 vest in three equal annual installments and have a weighted average grant date fair value of $71.37 and $68.90 , respectively. The RSUs granted in 2015 cliff vest in May 2018 and have a weighted average grant date fair value of $67.95 . 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). The Company anticipates that approximately 65% of the awards granted in 2017 will be settled in common stock and approximately 35% will be settled in cash, assuming full vesting. The Company anticipates that approximately 67% of the awards granted in 2016 will be settled in common stock and approximately 33% will be settled in cash, assuming full vesting. The Company anticipates that approximately 53% of the PBUs granted in 2015 will be settled in common stock and approximately 47% will be settled in cash, assuming full vesting. 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 and cash 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 the performance period. During 2017 , 2016 , and 2015 , the Company recognized $10.3 million , $8.6 million , and $5.8 million in compensation expense for these awards. As of December 31, 2017 , $14.1 million of total unrecognized compensation expense related to the awards is expected to be recognized over the remaining weighted-average service period of 1.3 years .

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2017
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. (In millions, except per share amounts) 2017 2016 2015 Numerators Income (loss) from continuing operations attributable to W. R. Grace & Co. shareholders $ 11.2 $ 107.0 $ 124.0 Income (loss) from discontinued operations, net of income taxes — (12.9 ) 20.2 Net income (loss) attributable to W. R. Grace & Co. shareholders $ 11.2 $ 94.1 $ 144.2 Denominators Weighted average common shares—basic calculation 68.1 70.1 72.0 Dilutive effect of employee stock options 0.1 0.4 0.6 Weighted average common shares—diluted calculation 68.2 70.5 72.6 Basic earnings per share attributable to W. R. Grace & Co. shareholders Income (loss) from continuing operations $ 0.16 $ 1.53 $ 1.72 Income (loss) from discontinued operations, net of income taxes — (0.19 ) 0.28 Net income (loss) $ 0.16 $ 1.34 $ 2.00 Diluted earnings per share attributable to W. R. Grace & Co. shareholders Income (loss) from continuing operations $ 0.16 $ 1.52 $ 1.71 Income (loss) from discontinued operations, net of income taxes — (0.19 ) 0.28 Net income (loss) $ 0.16 $ 1.33 $ 1.99 There were approximately 1.5 million , 1.3 million and 0.4 million anti-dilutive options outstanding for the years ended December 31, 2017 , 2016 and 2015 , respectively. On February 4, 2014, the Company announced that its Board of Directors authorized a share repurchase program of up to $500 million , which it completed on January 15, 2015. On February 5, 2015, the Company announced that its Board of Directors had authorized an additional share repurchase program of up to $500 million , which it completed on July 10, 2017. On February 8, 2017, the Company announced that its Board of Directors had authorized a new share repurchase program of up to $250 million , expected to be completed over 24 to 36 months at the discretion of management. 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, the strategic deployment of capital, and general market and economic conditions. During 2017 , 2016 and 2015 , the Company repurchased 935,435 , 2,775,297 , and 3,123,716 shares of Company common stock for $65.0 million , $195.1 million and $301.5 million , respectively, pursuant to the terms of the share repurchase programs. As of December 31, 2017 , $218.9 million remained under the current authorization.

Operating Segment Information

Operating Segment Information	12 Months Ended
	Dec. 31, 2017
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 refining, petrochemical and other chemical manufacturing applications. Advanced Refining Technologies ("ART"), Grace's joint venture with Chevron Products Company, a division of Chevron U.S.A. Inc. ("Chevron"), is managed in this segment. (See Note 18 .) Grace Catalysts Technologies comprises two operating segments, Grace Refining Technologies and Grace Specialty Catalysts, 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 coatings, consumer, industrial, and pharmaceutical 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 income from continuing operations attributable to W. R. Grace & Co. shareholders adjusted for interest income and expense; income taxes; costs related to legacy product, environmental and other claims; 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; income and expense items related to divested businesses, product lines, and certain other investments; gains and losses on sales of businesses, product lines, and certain other investments; third-party acquisition-related costs and the amortization of acquired inventory fair value adjustment; and certain other items that are not representative of underlying trends. Reportable Segment Data Year Ended December 31, (In millions) 2017 2016 2015 Net Sales Catalysts Technologies $ 1,276.5 $ 1,163.7 $ 1,162.1 Materials Technologies 440.0 434.9 466.1 Total $ 1,716.5 $ 1,598.6 $ 1,628.2 Adjusted EBIT Catalysts Technologies segment operating income $ 395.4 $ 367.8 $ 347.3 Materials Technologies segment operating income 100.6 104.0 96.9 Corporate costs (69.0 ) (59.4 ) (79.9 ) Gain on termination and curtailment of postretirement plans related to current businesses — 0.2 1.9 Certain pension costs (13.0 ) (12.3 ) (20.4 ) Total $ 414.0 $ 400.3 $ 345.8 Depreciation and Amortization Catalysts Technologies $ 87.1 $ 77.4 $ 68.1 Materials Technologies 19.6 19.5 23.2 Corporate 4.8 3.4 7.9 Total $ 111.5 $ 100.3 $ 99.2 Capital Expenditures Catalysts Technologies $ 100.9 $ 84.9 $ 66.3 Materials Technologies 20.9 24.0 24.6 Corporate 3.4 8.0 27.9 Total $ 125.2 $ 116.9 $ 118.8 Total Assets Catalysts Technologies $ 1,757.1 $ 1,675.1 $ 1,390.8 Materials Technologies 326.8 313.1 333.4 Corporate 823.1 923.6 1,051.0 Assets of discontinued operations — — 870.5 Total $ 2,907.0 $ 2,911.8 $ 3,645.7 Corporate costs include corporate support function costs and other corporate costs such as professional fees 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. Reconciliation of Reportable Segment Data to Financial Statements Grace Adjusted EBIT for the years ended December 31, 2017 , 2016 and 2015 is reconciled below to income from continuing operations before income taxes presented in the accompanying Consolidated Statements of Operations. Year Ended December 31, (In millions) 2017 2016 2015 Grace Adjusted EBIT $ 414.0 $ 400.3 $ 345.8 Pension MTM adjustment and other related costs, net (51.1 ) (60.3 ) (30.5 ) Costs related to legacy product, environmental and other claims (30.8 ) (35.4 ) (6.1 ) Restructuring and repositioning expenses (26.7 ) (38.6 ) (20.4 ) Accounts receivable reserve—Venezuela (10.0 ) — — Third-party acquisition-related costs (2.9 ) (2.5 ) — Income and expense items related to divested businesses (2.3 ) 0.1 1.5 Loss on early extinguishment of debt — (11.1 ) — Amortization of acquired inventory fair value adjustment — (8.0 ) — Gain (loss) on sale of product line — 1.7 — Gain on termination and curtailment of postretirement plans related to divested businesses — 0.3 2.6 Interest expense, net (78.5 ) (80.5 ) (99.1 ) Net income (loss) attributable to noncontrolling interests (0.8 ) — (0.1 ) Income (loss) from continuing operations before income taxes $ 210.9 $ 166.0 $ 193.7 The table below presents sales of similar products within each reportable segment. Year Ended December 31, (In millions) 2017 2016 2015 Catalysts Technologies: Refining catalysts $ 758.1 $ 724.9 $ 764.5 Polyolefin and chemical catalysts 518.4 438.8 397.6 Total $ 1,276.5 $ 1,163.7 $ 1,162.1 Materials Technologies: Coatings $ 142.2 $ 136.5 $ 133.6 Consumer/Pharma 123.3 121.9 125.1 Chemical process 153.5 142.6 137.0 Other 21.0 33.9 70.4 Total $ 440.0 $ 434.9 $ 466.1 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 customer location. Year Ended December 31, (In millions) 2017 2016 2015 Net Sales United States $ 437.3 $ 446.2 $ 444.7 Canada 48.7 44.5 45.3 Total North America 486.0 490.7 490.0 Europe Middle East Africa 667.7 647.8 621.2 Asia Pacific 459.8 348.9 390.9 Latin America 103.0 111.2 126.1 Total $ 1,716.5 $ 1,598.6 $ 1,628.2 Long-Lived Assets(1) United States $ 599.8 $ 564.5 $ 464.1 Canada 15.5 13.9 13.0 Total North America 615.3 578.4 477.1 Germany 142.2 109.7 110.9 Rest of Europe Middle East Africa 45.3 39.5 17.4 Total Europe Middle East Africa 187.5 149.2 128.3 Asia Pacific 21.1 21.5 25.9 Latin America 7.9 7.5 5.5 Total $ 831.8 $ 756.6 $ 636.8 ___________________________________________________________________________________________________________________ (1) Long-lived assets include properties and equipment and the noncurrent asset related to a planned hydroprocessing catalyst plant to be transferred to ART upon completion. (See Note 18.)

Unconsolidated Affiliate

Unconsolidated Affiliate	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
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 $125.9 million and $117.6 million as of December 31, 2017 and 2016 , respectively, and the amount included in "equity in earnings of unconsolidated affiliate" in the accompanying Consolidated Statements of Operations totaled $25.9 million , $29.8 million and $20.4 million for the years ended December 31, 2017 , 2016 and 2015 , respectively. ART is a private, limited liability company, taxed as a partnership, and accordingly does not have a quoted market price available. The following summary presents ART's assets, liabilities and results of operations. December 31, (In millions) 2017 2016 Summary Balance Sheet information: Current assets $ 239.8 $ 249.2 Noncurrent assets 91.5 84.8 Total assets $ 331.3 $ 334.0 Current liabilities $ 82.4 $ 102.0 Noncurrent liabilities 0.3 0.3 Total liabilities $ 82.7 $ 102.3 Year Ended December 31, (In millions) 2017 2016 2015 Summary Statement of Operations information: Net sales $ 447.3 $ 388.9 $ 415.3 Costs and expenses applicable to net sales 379.8 322.1 366.6 Income before income taxes 53.6 60.8 42.8 Net income 52.1 59.3 41.1 Grace and ART transact business on a regular basis and maintain several agreements in order to operate the joint venture. These agreements are treated as related party activities with an unconsolidated affiliate. Product manufacturing for ART is accounted for on a net basis, with a mark-up, in "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 on Grace's Consolidated Statement of Operations. The table below presents summary financial data related to transactions between Grace and ART. Year Ended December 31, (In millions) 2017 2016 2015 Product manufactured for ART $ 213.8 $ 210.4 $ 258.9 Mark-up on product manufactured for ART included as a reduction of Grace's cost of goods sold 4.2 4.2 5.1 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 41.7 33.8 31.6 The table below lists Grace balances related to ART. December 31, (in millions) 2017 2016 Accounts receivable $ 20.1 $ 14.9 Noncurrent asset 32.7 27.0 Accounts payable 22.3 28.7 Debt payable within one year 8.6 7.6 Debt payable after one year 33.8 31.9 Noncurrent liability 32.7 27.0 The noncurrent asset and noncurrent liability in the table above represent spending to date related to a planned residue hydroprocessing catalyst production plant in Lake Charles, Louisiana. Grace manages the design and construction of the plant, and the asset will be included in "other assets" in Grace's Consolidated Balance Sheets until construction is completed. Grace has likewise recorded a liability for the transfer of the asset to ART upon completion, included in "other liabilities" in the Consolidated Balance Sheets. 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 2019. No amounts were outstanding at December 31, 2017 and 2016 .

Quarterly Summary and Statistic

Quarterly Summary and Statistical Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Quarterly Summary and Statistical Information (Unaudited)	(In millions, except per share amounts) March 31 June 30 September 30 December 31(3) 2017 Net sales $ 398.0 $ 429.5 $ 429.5 $ 459.5 Gross profit 153.2 169.3 173.3 167.5 Net income (loss) 42.9 43.5 47.1 (123.1 ) Net income (loss) attributable to W. R. Grace & Co. shareholders 42.9 43.9 47.4 (123.0 ) Net income (loss) per share:(1) Basic earnings (loss) per share: Net income (loss) $ 0.63 $ 0.64 $ 0.70 $ (1.81 ) Diluted earnings (loss) per share: Net income (loss) 0.63 0.64 0.70 (1.81 ) Dividends declared per share 0.21 0.21 0.21 0.21 Market price of common stock:(2) High $ 74.63 $ 72.72 $ 73.77 $ 77.37 Low 67.54 67.12 65.84 69.37 Close 69.71 72.01 72.15 70.13 ___________________________________________________________________________________________________________________ (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) Principal market: New York Stock Exchange. (3) Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017. (In millions, except per share amounts) March 31 June 30 September 30 December 31(5) 2016 Net sales $ 362.8 $ 390.5 $ 404.5 $ 440.8 Gross profit 152.7 173.2 168.2 161.8 Net income (loss) 0.3 38.5 39.7 15.6 Net income (loss) attributable to W. R. Grace & Co. shareholders 0.5 38.7 39.6 15.3 Net income (loss) per share:(1) Basic earnings (loss) per share: Net income (loss) $ 0.01 $ 0.55 $ 0.56 $ 0.22 Diluted earnings (loss) per share: Net income (loss) 0.01 0.55 0.56 0.22 Dividends declared per share — 0.17 0.17 0.17 Market price of common stock:(2)(3) High $ 98.15 (4) $ 80.39 $ 80.56 $ 74.38 Low 63.84 70.59 71.47 63.37 Close 71.18 73.21 73.80 67.64 ___________________________________________________________________________________________________________________ (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) Principal market: New York Stock Exchange. (3) Share prices subsequent to February 3, 2016, reflect the Separation and exclude separate trading of GCP common stock. (4) Price is a pre-Separation market price of common stock. (5) Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.

SCHEDULE II-VALUATION AND QUALI

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES	FINANCIAL STATEMENT SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (In millions) For the Year Ended December 31, 2017 Description Balance at beginning of period Additions charged to costs and expenses Deductions Other, net(1) Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable(2) $ 2.8 $ 10.6 $ (1.3 ) $ (0.1 ) $ 12.0 Valuation allowance for deferred tax assets(3) 31.4 0.3 (19.7 ) — 12.0 Reserves: Reserves for environmental remediation 66.3 24.4 (20.4 ) — 70.3 Reserves for retained obligations of divested businesses 11.7 1.5 (0.4 ) — 12.8 For the Year Ended December 31, 2016 Description Balance at beginning of period Additions charged to costs and expenses Deductions Other, net(1) Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable $ 1.4 $ 2.4 $ (1.1 ) $ 0.1 $ 2.8 Valuation allowance for deferred tax assets(4) 8.4 11.6 (9.1 ) 20.5 31.4 Reserves: Reserves for environmental remediation 55.2 29.2 (18.1 ) — 66.3 Reserves for retained obligations of divested businesses 13.5 — (1.8 ) — 11.7 For the Year Ended December 31, 2015 Description Balance at beginning of period Additions charged to costs and expenses Deductions Other, net(1) Balance at end of period Valuation and qualifying accounts deducted from assets: Allowances for notes and accounts receivable $ 1.0 $ 0.5 $ (0.1 ) $ — $ 1.4 Valuation allowance for deferred tax assets(5) 10.7 0.4 (2.6 ) (0.1 ) 8.4 Reserves: Reserves for environmental remediation 61.1 6.4 (12.3 ) — 55.2 Reserves for retained obligations of divested businesses 13.5 — — — 13.5 ___________________________________________________________________________________________________________________ (1) Effects of currency translation and the Separation. (2) The allowance for accounts receivable increased primarily due to a $10.0 million charge to fully reserve for a trade receivable from a Venezuela-based customer related to increased economic uncertainty and the recent political unrest and sanctions. (3) The valuation allowance decreased $19.4 million from December 31, 2016 , to December 31, 2017 . The decrease was primarily due to the effects of U.S. tax reform. (4) The valuation allowance increased $23.0 million from December 31, 2015 , to December 31, 2016 . The increase was primarily due to the adoption of ASU 2016-09 as well as the ability to utilize NOL carryforwards as a result of the Separation. (5) The valuation allowance decreased $2.3 million from December 31, 2014 , to December 31, 2015 . The decrease was primarily due to a reduction in the valuation allowance on state NOL carryforwards.

Acquisition (Notes)

Acquisition (Notes)	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	On December 14, 2017, Grace signed a definitive agreement to acquire the polyolefin catalysts business of Albemarle Corporation for $416 million , subject to regulatory approvals and other customary closing conditions. This acquisition would be complementary to Grace's specialty catalysts business and would strengthen Grace's catalysts technology portfolio, commercial relationships, and manufacturing network. On June 30, 2016, Grace acquired the assets of BASF's polyolefin catalysts business for total consideration of $250.6 million , including an estimated $3.3 million holdback liability, which was paid during the 2017 second quarter. The business is included in the Specialty Catalysts operating segment of the Catalysts Technologies reportable segment. The acquisition purchase price was allocated to the tangible and identifiable intangible assets acquired based on their estimated fair values at the acquisition date in accordance with ASC 805 "Business Combinations." The excess of the purchase price over the fair value of the tangible and intangible assets acquired was recorded as goodwill. The goodwill recognized is attributable to the expected growth and operating synergies that Grace expects to realize from this acquisition. Approximately $43 million of goodwill generated from the acquisition will be deductible for U.S. income tax purposes over a period of 15 years. (In millions) Inventories $ 30.2 Properties and equipment 95.0 Goodwill 63.8 Intangible assets 61.6 Net assets acquired $ 250.6 The table below presents the intangible assets acquired as part of the acquisition of the assets of BASF's polyolefin catalysts business and the periods over which they will be amortized. Amount (In millions) Weighted Average Amortization Period (in years) Customer Lists $ 39.9 20.0 Trademarks 13.4 20.0 Technology 8.3 20.0 Total $ 61.6 20.0

Discontinued Operations (Notes)

Discontinued Operations (Notes)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	As a result of the Separation and Distribution, GCP is now an independent public company and its common stock is listed under the symbol “GCP” on the New York Stock Exchange. Grace does not beneficially own any shares of GCP common stock and will not consolidate the financial results of GCP in its future financial reporting, as GCP is no longer a related party to Grace subsequent to the Separation. GCP’s historical financial results through the Distribution Date are reflected in Grace’s Consolidated Financial Statements as discontinued operations. Separation and Distribution Agreement Prior to the completion of the Separation and the Distribution, W. R. Grace & Co., Grace–Conn. and GCP entered into a Separation and Distribution Agreement and certain related agreements that govern the post-Separation relationship between Grace and GCP. The Separation and Distribution Agreement identifies the transfer of Grace's assets and liabilities that are specifically identifiable or otherwise allocable to GCP, the elimination of Grace’s equity interest in GCP, the removal of certain non-recurring separation costs directly related to the Separation and Distribution, the cash distribution from GCP to Grace, the reduction in Grace's debt using the cash received from GCP, and it provides for when and how these transfers, assumptions and assignments have occurred or will occur. Tax Sharing Agreement W. R. Grace & Co., Grace–Conn. and GCP entered into a Tax Sharing Agreement that generally governs the parties’ respective rights, responsibilities and obligations after the Distribution with respect to taxes (including taxes arising in the ordinary course of business and taxes, if any, incurred as a result of any failure of the Distribution and certain related transactions to qualify under Sections 355 and certain other relevant provisions of the Internal Revenue Code (the “Code”)), tax attributes, the preparation and filing of tax returns, tax elections, tax contests, and certain other tax matters. In addition, the Tax Sharing Agreement imposes certain restrictions on GCP and its subsidiaries (including restrictions on share issuances, business combinations, sales of assets and similar transactions) that are designed to preserve the qualification of the Distribution and certain related transactions under Sections 355 and certain other relevant provisions of the Code. The Tax Sharing Agreement provides special rules that allocate tax liabilities in the event the Distribution, together with certain related transactions, does not so qualify. In general, under the Tax Sharing Agreement, each party is expected to be responsible for any taxes imposed on, and certain related amounts payable by, GCP or Grace that arise from the failure of the Distribution and certain related transactions, to qualify under Sections 355 and certain other relevant provisions of the Code, to the extent that the failure to so qualify is attributable to actions, events or transactions relating to such party’s respective stock, assets or business, or a breach of the relevant representations or covenants made by that party in the Tax Sharing Agreement. The foregoing is a summary of the Separation and Distribution Agreement and the Tax Sharing Agreement. Grace has filed the full texts of the Separation and Distribution Agreement and the Tax Sharing Agreement with the SEC, which are readily available on the Internet at www.sec.gov. GCP’s historical financial results through the Distribution Date and other effects of the Separation are presented as discontinued operations as summarized below: Year Ended December 31, (In millions) 2016 2015 Net sales $ 99.6 $ 1,423.3 Cost of goods sold 62.6 907.5 Gross profit 37.0 515.8 Selling, general and administrative expenses 21.6 251.2 Research and development expenses 1.7 22.5 Loss in Venezuela — 59.6 Repositioning expenses 22.0 55.1 Interest expense and related financing costs 0.7 1.5 Other expense, net 3.9 9.9 Total costs and expenses 49.9 399.8 (Loss) Income from discontinued operations before income taxes (12.9 ) 116.0 Benefit from (provision for) income taxes 0.1 (95.0 ) (Loss) Income from discontinued operations after income taxes (12.8 ) 21.0 Less: Net income attributable to noncontrolling interests (0.1 ) (0.8 ) Net (loss) income from discontinued operations $ (12.9 ) $ 20.2 In January 2016, GCP completed the sale of $525.0 million aggregate principal amount of 9.500% Senior Notes due in 2023. GCP used a portion of these proceeds to fund a $500.0 million distribution to Grace in connection with the Separation and the Distribution. In February 2016, GCP entered into a credit agreement that provides for new senior secured credit facilities in an aggregate principal amount of $525.0 million , consisting of term loans in an aggregate principal amount of $275.0 million maturing in 2022 and of revolving loans in an aggregate principal amount of $250.0 million maturing in 2021, which were undrawn at closing. GCP used a portion of these proceeds to fund a $250.0 million distribution to Grace in connection with the Separation and the Distribution.

Basis of Presentation and Sum30

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
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 certain 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 certain 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 and Chief Operating 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 amount 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: • 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 19 ); and • Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate obligation, such as litigation (see Note 10 ), income taxes (see Note 7 ), and environmental remediation (see Note 10 ).
Revenue Recognition	Grace recognizes revenue when all of the following criteria are satisfied: risk of loss and title transfer to the customer; the price is fixed and determinable; persuasive evidence of a sales arrangement exists; and collectability is reasonably assured. The point at which risk of loss and title transfers to a customer is determined based on delivery terms, which are generally included in customer contracts of sale, order confirmation documents, and invoices.
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 market. 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, 3 to 10 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. Grace is currently in the process of conducting a depreciation study to review the useful lives of machinery and equipment, including an evaluation of historical retirement data as well as industry review and analysis. This evaluation will be completed by the end of the 2018 first quarter. Grace expects this review to result in increased useful lives (and lower depreciation expense) and will apply the change to new and existing assets on a prospective basis as a change in accounting estimate effective January 1, 2018.	[1]
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 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. 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.
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 performance based units (CSPBU) 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 May 2014, the FASB issued ASU 2014-09 "Revenue from Contracts with Customers." This update is intended to remove inconsistencies and weaknesses in revenue requirements; provide a more robust framework for addressing revenue issues; improve comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets; provide more useful information to users of financial statements through improved disclosure requirements; and simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. The standard allows for two methods of adoption: (a) full retrospective adoption, meaning the standard is applied to all periods presented, or (b) modified retrospective adoption, meaning the cumulative effect of applying the new standard is recognized as an adjustment to the opening retained earnings balance. Grace has assessed specific areas of the standard and its impact on the Consolidated Financial Statements. Grace will adopt this standard in the 2018 first quarter under the modified retrospective approach and does not expect it to have a material effect on the Consolidated Financial Statements. In February 2016, the FASB issued ASU 2016-02 "Leases (Topic 842)." This update is intended to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The core principle of Topic 842 is that a lessee should recognize the assets and liabilities that arise from leases. A lessee should recognize in the statement of financial position a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the underlying asset for the lease term, including optional payments where they are reasonably certain to occur. Currently, as a lessee, Grace is a party to a number of leases which, under existing guidance, are classified as operating leases and not recorded on the balance sheet but are expensed as incurred. Under the new standard, many of these leases will be recorded on the Consolidated Balance Sheets. Grace will adopt the standard in the 2019 first quarter and at this time cannot reasonably estimate the effect of adoption. In November 2016, the FASB issued ASU 2016-18 "Statement of Cash Flows (Topic 230): Restricted Cash," which requires that a statement of cash flows explain the change during the period in the total of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents. Therefore, amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. Grace will adopt the update in the 2018 first quarter and does not expect it to have a material effect on the Consolidated Financial Statements. As of December 31, 2017 and 2016, restricted cash included in the Consolidated Balance Sheets was $10.7 million and $10.0 million , respectively. In January 2017, the FASB issued ASU 2017-01 "Business Combinations (Topic 805)," which provides a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. If the screen is not met, the amendments in this update (1) require that to be considered a business, a set must include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create output, and (2) remove the evaluation of whether a market participant could replace missing elements. The amendments in this update also narrow the definition of the term "output" so that the term is consistent with how outputs are described in Topic 606. Public business entities are required to apply the amendments in this update to annual periods beginning after December 15, 2017, including interim periods within those periods, with early application permitted. Grace will adopt the update when it becomes effective and does not expect it to have a material effect on the Consolidated Financial Statements. In January 2017, the FASB issued ASU 2017-04 "Intangibles—Goodwill and Other (Topic 350)." This update modifies the concept of impairment from the condition that exists when the carrying amount of goodwill exceeds its implied fair value to the condition that exists when the carrying amount of a reporting unit exceeds its fair value. An entity no longer will determine goodwill impairment by calculating the implied fair value of goodwill by assigning the fair value of a reporting unit to all of its assets and liabilities as if that reporting unit had been acquired in a business combination ("Step 2"). Because these amendments eliminate Step 2 from the goodwill impairment test, they should reduce the cost and complexity of evaluating goodwill for impairment. Grace is required to adopt the amendments in this update for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Grace is currently evaluating the timing of adoption and does not expect the update to have a material effect on the Consolidated Financial Statements. In March 2017, the FASB issued ASU 2017-07 "Compensation—Retirement Benefits (Topic 715)." This update requires that the service cost component of net benefit cost be presented with other compensation costs arising from services rendered. The remaining net benefit cost is either presented as a line item in the statement of operations outside of a subtotal for income from operations, if presented, or disclosed separately. Only the service cost component of net benefit expense can be capitalized. The update will affect the classification of defined benefit pension expense within the Consolidated Statements of Operations, with changes to amounts included in "cost of goods sold," "selling, general and administrative expenses," "research and development expenses," and "other (income) expense, net." Grace will adopt the update in the 2018 first quarter. In May 2017, the FASB issued ASU 2017-09 "Compensation—Stock Compensation (Topic 718)." This update clarifies the existing definition of the term "modification," which is currently defined as "a change in any of the terms or conditions of a share-based payment award." The update requires entities to account for modifications of share-based payment awards unless the (1) fair value, (2) vesting conditions, and (3) classification as an equity instrument or a liability instrument of the modified award are the same as of the original award before modification. Grace is required to adopt the amendments in this update for fiscal years and interim periods beginning after December 15, 2017, with early adoption permitted. Grace does not currently have any modifications of share-based awards and will adopt the update when it becomes effective. In January 2018, the FASB issued ASU 2018-01 "Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842." This update provides an optional transition practical expedient that allows an entity to elect not to evaluate under Topic 842 existing or expired land easements not previously accounted for as leases. All land easements entered into or modified after the adoption of Topic 842 must be evaluated under Topic 842. Grace, which typically does not account for easements under current lease accounting, will use the transition practical expedient when adopting Topic 842 in the 2019 first quarter and at this time cannot reasonably estimate the effect of adoption. In February 2018, the FASB issued ASU 2018-02 "Income Statement—Reporting Comprehensive Income (Topic 220)." This update addresses the revaluation of deferred tax assets and liabilities due to the Tax Cuts and Jobs Act of 2017 impacting income from continuing operations, even if the initial income tax effects were recognized in other comprehensive income. The update allows entities to reclassify the tax effects that were originally in other comprehensive income from accumulated other comprehensive income to retained earnings. The update requires entities to disclose whether the election was made and a description of the income tax effects. The update can be: (a) applied to the period of adoption, or (b) applied retrospectively to each period in which the Tax Cuts and Jobs Act of 2017 is in effect. Grace is required to adopt the amendments in this update for fiscal years and interim periods beginning after December 15, 2018, with early adoption permitted. Grace is currently evaluating the timing and effect of adoption. U.S. Tax Reform On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (the "Act") was signed into law, making significant changes to the Internal Revenue Code. Changes include a federal corporate tax rate decrease from 35% to 21% for tax years beginning after December 31, 2017, the transition of U.S. international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of foreign earnings. Grace has estimated its provision for income taxes in accordance with the Act and guidance available as of the date of this filing and as a result has recorded $143.0 million as additional income tax expense in the 2017 fourth quarter, the period in which the legislation was enacted. The provisional amount related to the remeasurement of certain deferred tax assets and liabilities, based on the rates at which they are expected to reverse in the future, was $120.1 million . The provisional amounts related to the one-time transition tax on the mandatory deemed repatriation of foreign earnings and the state and foreign taxes on the unremitted earnings were $37.4 million and $4.9 million respectively. Additionally, Grace provisionally released valuation allowances on a portion of its state net operating losses and federal tax credits of $2.0 million and $17.4 million . On December 22, 2017, the SEC issued Staff Accounting Bulletin No. 118 ("SAB 118") to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed (including computations) in reasonable detail to complete the accounting for certain income tax effects of the Act. In accordance with SAB 118, Grace has determined that the $120.1 million of deferred tax expense recorded in connection with the remeasurement of certain deferred tax assets and liabilities and the $37.4 million of current tax expense recorded in connection with the transition tax on the mandatory deemed repatriation of foreign earnings, as well as the state and foreign taxes on unremitted earnings and the release of the valuation allowances, were provisional amounts and reasonable estimates at December 31, 2017. Additional work is necessary for a more detailed analysis of Grace's deferred tax assets and liabilities and its historical foreign earnings as well as potential correlative adjustments. Any subsequent adjustment to these amounts will be recorded to current tax expense in the 2018 quarter during which the analysis is completed, which is expected to be during the second half of 2018. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income ("GILTI") provisions of the Act. Grace has not completed its analysis in order to make a policy decision on accounting for GILTI. See Note 7 for more information related to income taxes and U.S. tax reform.
[1]	(1)Includes federal, state, provincial or local jurisdictions, as applicable.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 : December 31, (In millions) 2017 2016 Raw materials $ 48.8 $ 57.7 In process 33.0 33.4 Finished products 124.7 115.8 Other 24.4 21.1 $ 230.9 $ 228.0

Properties and Equipment (Table

Properties and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule of properties and equipment	December 31, (In millions) 2017 2016 Land $ 14.2 $ 10.0 Buildings 404.5 375.4 Information technology and equipment 136.6 125.3 Machinery, equipment and other 1,571.8 1,445.8 Projects under construction 135.4 100.6 Properties and equipment, gross 2,262.5 2,057.1 Accumulated depreciation and amortization (1,463.4 ) (1,327.5 ) Properties and equipment, net $ 799.1 $ 729.6
Schedule of minimum future payments under operating leases	At December 31, 2017 , minimum future non-cancelable payments for operating leases are: (In millions) 2018 $ 10.4 2019 7.3 2020 5.5 2021 3.0 2022 2.8 Thereafter 39.3 $ 68.3

Goodwill and Other Intangible33

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 and 2016 , are as follows: (In millions) Catalysts Technologies Materials Technologies Total Grace Balance, December 31, 2015 $ 292.7 $ 43.8 $ 336.5 Goodwill acquired during the year 63.8 — 63.8 Foreign currency translation (3.0 ) (0.6 ) (3.6 ) Write-off related to exited product lines — (2.5 ) (2.5 ) Balance, December 31, 2016 353.5 40.7 394.2 Goodwill acquired during the year — 2.4 2.4 Foreign currency translation 4.2 1.6 5.8 Balance, December 31, 2017 $ 357.7 $ 44.7 $ 402.4
Summary of net book value of other intangible assets	Grace's net book value of other intangible assets at December 31, 2017 and 2016 , was $255.4 million and $269.1 million , respectively, detailed as follows: December 31, 2017 December 31, 2016 (In millions) Gross Carrying Amount Accumulated Amortization Gross Carrying Accumulated Technology $ 214.7 $ 41.5 $ 222.3 $ 38.9 Customer lists 55.8 8.8 69.6 20.3 Trademarks 25.5 2.6 25.3 1.5 Other 16.0 3.7 15.7 3.1 Total $ 312.0 $ 56.6 $ 332.9 $ 63.8
Summary of estimated amortization expenses	At December 31, 2017 , estimated future annual amortization expense for intangible assets is: (In millions) 2018 $ 15.4 2019 15.4 2020 15.1 2021 14.9 2022 14.8 Thereafter 179.8 $ 255.4

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Components of debt	Components of Debt December 31, (In millions) 2017 2016 5.125% senior notes due 2021, net of unamortized debt issuance costs of $5.8 at December 31, 2017 (2016—$7.3) $ 694.2 $ 692.7 U.S. dollar term loan, net of unamortized debt issuance costs and discounts of $4.3 at December 31, 2017 (2016—$5.7) 404.1 402.7 5.625% senior notes due 2024, net of unamortized debt issuance costs of $3.5 at December 31, 2017 (2016—$4.0) 296.5 296.0 Euro term loan, net of unamortized debt issuance costs and discounts of $1.0 at December 31, 2017 (2016—$1.3) 94.0 82.5 Debt payable to unconsolidated affiliate 42.4 39.5 Deferred payment obligation — 30.0 Other borrowings(1) 12.7 40.7 Total debt 1,543.9 1,584.1 Less debt payable within one year 20.1 76.5 Debt payable after one year $ 1,523.8 $ 1,507.6 Weighted average interest rates on total debt 4.7 % 4.6 % ___________________________________________________________________________________________________________________ (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, 2017 , were as follows: (In millions) 2018 $ 20.1 2019 8.7 2020 7.4 2021 1,198.2 2022 5.0 Thereafter 304.5 Total debt $ 1,543.9

Fair Value Measurements and R35

Fair Value Measurements and Risk (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	At December 31, 2017 , the carrying amounts and fair values of Grace's debt were as follows: December 31, 2017 December 31, 2016 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 5.125% senior notes due 2021(1) $ 694.2 $ 728.7 $ 692.7 $ 721.3 U.S. dollar term loan(2) 404.1 409.7 402.7 408.2 5.625% senior notes due 2024(1) 296.5 321.3 296.0 311.5 Euro term loan(2) 94.0 93.7 82.5 82.0 Other borrowings 55.1 55.1 110.2 110.2 Total debt $ 1,543.9 $ 1,608.5 $ 1,584.1 $ 1,633.2 ___________________________________________________________________________________________________________________ (1) Carrying amounts are net of unamortized debt issuance costs of $5.8 million and $3.5 million at December 31, 2017 , and $7.3 million and $4.0 million as of December 31, 2016 , related to the 5.125% senior notes due 2021 and 5.625% senior notes due 2024, respectively. (2) Carrying amounts are net of unamortized debt issuance costs and discounts of $4.3 million and $1.0 million at December 31, 2017 , and $5.7 million and $1.3 million as of December 31, 2016 , related to the U.S. dollar term loan and euro term loan, respectively.
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, 2017 and 2016 : Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Currency derivatives $ 3.1 $ — $ 3.1 $ — Total Assets $ 3.1 $ — $ 3.1 $ — Liabilities Currency derivatives $ 23.8 $ — $ 23.8 $ — Interest rate derivatives 1.8 — 1.8 — Total Liabilities $ 25.6 $ — $ 25.6 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets Currency derivatives $ 8.8 $ — $ 8.8 $ — Total Assets $ 8.8 $ — $ 8.8 $ — Liabilities Interest rate derivatives $ 6.0 $ — $ 6.0 $ — Currency derivatives 0.9 — 0.9 — Total Liabilities $ 6.9 $ — $ 6.9 $ —
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, 2017 and 2016 : Asset Derivatives Liability Derivatives December 31, 2017 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.7 Other current liabilities $ 1.4 Interest rate contracts Other current assets — Other current liabilities 1.3 Currency contracts Other assets — Other liabilities 22.2 Interest rate contracts Other assets — Other liabilities 0.5 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.4 Other current liabilities 0.2 Total derivatives $ 3.1 $ 25.6 Asset Derivatives Liability Derivatives December 31, 2016 Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 4.0 Other current liabilities $ — Interest rate contracts Other current assets — Other current liabilities 2.8 Currency contracts Other assets 4.0 Other liabilities — Interest rate contracts Other assets — Other liabilities 3.2 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.8 Other current liabilities 0.9 Total derivatives $ 8.8 $ 6.9
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, 2017 , 2016 , and 2015 : Year Ended December 31, 2017 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 0.9 Interest expense $ (2.7 ) Currency contracts(1) (3.6 ) Other expense (2.9 ) Total derivatives $ (2.7 ) $ (5.6 ) ___________________________________________________________________________________________________________________ (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, 2016 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (2.2 ) Interest expense $ (4.1 ) Currency contracts (0.1 ) Other expense 0.8 Total derivatives $ (2.3 ) $ (3.3 ) Year Ended December 31, 2015 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 OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (5.6 ) Interest expense $ (3.8 ) Currency contracts 1.4 Other expense 0.7 Total derivatives $ (4.2 ) $ (3.1 ) 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, 2017 2016 2015 (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 $ 79.5 $ (8.4 ) $ 81.5 $ 13.3 $ 99.4 $ (13.8 ) Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Amount of gain or (loss) reclassified from accumulated OCI into income $ (2.7 ) $ — $ (4.1 ) $ — $ (3.8 ) $ — Currency contracts Amount of gain or (loss) reclassified from accumulated OCI into income — (2.9 ) — 0.8 — 0.7 Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 0.6 — — — —
Schedule of Net Investment Hedges in ACOI [Table Text Block]	The following tables present the location and amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges for the years ended December 31, 2017 , 2016 , and 2015 . There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented in the tables below. Year Ended December 31, 2017 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ (21.9 ) Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ (11.2 ) Foreign currency denominated deferred intercompany royalties (6.5 ) $ (17.7 ) Year Ended December 31, 2016 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Derivatives in ASC 815 net investment hedging relationships: Cross-currency swap $ 5.6 Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ 4.6 Foreign currency denominated deferred intercompany royalties 2.5 $ 7.1 Year Ended December 31, 2015 Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ 18.3

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
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 2017 , 2016 , and 2015 are as follows: (In millions) 2017 2016 2015 Income from continuing operations before income taxes: Domestic $ 28.3 $ 72.7 $ 97.1 Foreign 182.6 93.3 96.6 Total $ 210.9 $ 166.0 $ 193.7 Benefit from (provision for) income taxes: Federal—deferred $ (144.6 ) $ (11.8 ) $ (35.4 ) State and local—current 0.2 (0.7 ) 4.1 State and local—deferred (1.7 ) (17.7 ) (6.4 ) Foreign—current (50.8 ) (36.6 ) (23.5 ) Foreign—deferred (3.6 ) 7.8 (8.6 ) Total $ (200.5 ) $ (59.0 ) $ (69.8 )
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 35% and Grace's overall income tax provision is summarized as follows: (In millions) 2017 2016 2015 Tax provision at U.S. federal income tax rate $ (73.8 ) $ (58.1 ) $ (67.8 ) Change in benefit (provision) resulting from: Provisional charge related to U.S. tax reform (143.0 ) — — Effect of tax rates in foreign jurisdictions 13.3 6.8 3.0 Research and development credit 5.1 — — Stock option exercises 2.8 6.7 — Nontaxable income/non-deductible expenses (2.6 ) (2.5 ) (0.9 ) State and local income taxes, net (1.8 ) (4.7 ) (2.9 ) U.S. tax on foreign earnings (1.2 ) (0.9 ) (1.7 ) Decrease (increase) in valuation allowance (0.3 ) (2.5 ) 1.6 Other 1.0 (3.8 ) (1.1 ) Benefit from (provision for) income taxes $ (200.5 ) $ (59.0 ) $ (69.8 )
Summary of tax attributes giving rise to deferred tax assets and liabilities	Deferred Tax Assets and Liabilities As of December 31, 2017 and 2016 , the tax attributes giving rise to deferred tax assets and liabilities consisted of the following items. December 31, (In millions) 2017 2016 Deferred tax assets: Federal tax credit carryforwards $ 269.6 $ 183.2 Pension liabilities 104.8 120.1 U.S. net operating loss carryforwards 89.5 293.6 State net operating loss carryforwards 58.2 50.9 Research and development 22.8 35.4 Prepaid royalties 21.4 20.8 Liability for environmental remediation 16.4 24.6 Reserves and allowances 15.2 31.1 Foreign net operating loss carryforwards 6.6 5.9 Liability for asbestos-related litigation — 11.1 Other 14.5 29.0 Total deferred tax assets $ 619.0 $ 805.7 Deferred tax liabilities: Properties and equipment $ (32.0 ) $ (38.5 ) Intangible assets (15.1 ) (18.4 ) Pension assets — (6.1 ) Other (11.3 ) (4.7 ) Total deferred tax liabilities $ (58.4 ) $ (67.7 ) Valuation allowance: Federal tax credit carryforwards $ (0.3 ) $ (17.7 ) State net operating loss carryforwards (9.2 ) (11.2 ) Foreign net operating loss carryforwards (2.8 ) (2.5 ) Total valuation allowance (12.3 ) (31.4 ) Net deferred tax assets $ 548.3 $ 706.6
Summary of information about uncertain tax positions	A rollforward of the unrecognized tax benefits for the three years ended December 31, 2017 , follows. (In millions) Unrecognized Tax Benefits Balance, December 31, 2014 $ 26.5 Additions for current year tax positions 0.1 Additions for prior year tax positions 0.8 Reductions for prior year tax positions and reclassifications (1.6 ) Reductions for expirations of statute of limitations (1.5 ) Settlements (1.2 ) Balance, December 31, 2015 23.1 Additions for current year tax positions 6.8 Additions for prior year tax positions 0.2 Reductions for prior year tax positions and reclassifications (0.2 ) Settlements (3.3 ) Transferred to GCP upon Separation (7.9 ) Balance, December 31, 2016 18.7 Additions for current year tax positions 0.8 Additions for prior year tax positions 0.7 Reductions for prior year tax positions and reclassifications (2.5 ) Balance, December 31, 2017 $ 17.7
Schedule of open tax years by major jurisdiction	The following table summarizes these open tax years by major jurisdiction: Tax Jurisdiction(1) Examination in Progress Examination Not Initiated United States—Federal 2007, 2009 2010-2016 United States—States 2010-2014 2015-2016 Germany 2014-2016 None Sweden None 2013-2016 ___________________________________________________________________________________________________________________ (1) Includes federal, state, provincial or local jurisdictions, as applicable.

Pension Plans and Other Postr37

Pension Plans and Other Postretirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2017
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 2017 and 2016 : Defined Benefit Pension Plans (In millions) U.S. Non-U.S. Total 2017 2016 2017 2016 2017 2016 Change in Projected Benefit Obligation (PBO): Benefit obligation at beginning of year $ 1,274.2 $ 1,238.8 $ 269.1 $ 238.8 $ 1,543.3 $ 1,477.6 Service cost 17.1 17.8 8.4 6.8 25.5 24.6 Interest cost 42.0 40.5 4.4 5.1 46.4 45.6 Amendments — (1.3 ) — — — (1.3 ) Settlements/curtailments — — — (2.3 ) — (2.3 ) Acquisitions — — 0.4 — 0.4 — Actuarial (gain) loss 88.3 62.3 13.4 39.9 101.7 102.2 Benefits paid (91.2 ) (83.9 ) (7.8 ) (7.5 ) (99.0 ) (91.4 ) Currency exchange translation adjustments — — 35.2 (11.7 ) 35.2 (11.7 ) Other (4.8 ) — — — (4.8 ) — Benefit obligation at end of year $ 1,325.6 $ 1,274.2 $ 323.1 $ 269.1 $ 1,648.7 $ 1,543.3 Change in Plan Assets: Fair value of plan assets at beginning of year $ 1,086.4 $ 1,067.2 $ 18.2 $ 18.7 $ 1,104.6 $ 1,085.9 Actual return on plan assets 112.7 95.6 1.6 (0.5 ) 114.3 95.1 Employer contributions 9.6 7.5 8.2 8.4 17.8 15.9 Settlements — — — (1.3 ) — (1.3 ) Benefits paid (91.2 ) (83.9 ) (7.8 ) (7.5 ) (99.0 ) (91.4 ) Currency exchange translation adjustments — — 1.3 0.4 1.3 0.4 Other (7.7 ) — — — (7.7 ) — Fair value of plan assets at end of year $ 1,109.8 $ 1,086.4 $ 21.5 $ 18.2 $ 1,131.3 $ 1,104.6 Funded status at end of year (PBO basis) $ (215.8 ) $ (187.8 ) $ (301.6 ) $ (250.9 ) $ (517.4 ) $ (438.7 ) Amounts recognized in the Consolidated Balance Sheets consist of: Current liabilities $ (7.0 ) $ (7.4 ) $ (8.0 ) $ (7.0 ) $ (15.0 ) $ (14.4 ) Noncurrent liabilities (208.8 ) (180.4 ) (293.6 ) (243.9 ) (502.4 ) (424.3 ) Net amount recognized $ (215.8 ) $ (187.8 ) $ (301.6 ) $ (250.9 ) $ (517.4 ) $ (438.7 ) Amounts recognized in Accumulated Other Comprehensive (Income) Loss consist of: Prior service credit $ (3.9 ) $ (4.3 ) $ (0.1 ) $ (0.1 ) $ (4.0 ) $ (4.4 ) Net amount recognized $ (3.9 ) $ (4.3 ) $ (0.1 ) $ (0.1 ) $ (4.0 ) $ (4.4 ) Defined Benefit Pension Plans (In millions) U.S. Non-U.S. 2017 2016 2017 2016 Weighted Average Assumptions Used to Determine Benefit Obligations as of December 31: Discount rate 3.57 % 4.06 % 1.84 % 1.91 % Rate of compensation increase 4.10 % 4.10 % 2.64 % 3.09 % Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended December 31: Discount rate for determining service cost 4.41 % 4.68 % 2.09 % 2.90 % Discount rate for determining interest cost 3.42 % 3.38 % 1.69 % 2.26 % Expected return on plan assets 5.50 % 5.50 % 4.69 % 5.08 % Rate of compensation increase 4.10 % 4.10 % 3.09 % 3.09 %
Schedule of Net Benefit Cost and Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	2017 2016 2015 U.S. Non-U.S. U.S. Non-U.S. U.S. Non-U.S. Net Periodic Benefit Cost (Income) Service cost $ 17.1 $ 8.4 $ 17.8 $ 6.8 $ 25.7 $ 11.7 Interest cost 42.0 4.4 40.5 5.1 55.1 16.1 Expected return on plan assets (57.5 ) (0.9 ) (56.7 ) (1.0 ) (70.4 ) (13.0 ) Amortization of prior service cost (credit) (0.4 ) — (0.2 ) — 0.3 — Annual mark-to-market adjustment 36.0 13.2 23.3 40.1 42.0 (0.1 ) Net curtailment and settlement gain — — — (1.0 ) — — Net periodic benefit cost (income) 37.2 25.1 24.7 50.0 52.7 14.7 Less: discontinued operations — — — — (4.0 ) (16.8 ) Net periodic benefit cost (income) from continuing operations $ 37.2 $ 25.1 $ 24.7 $ 50.0 $ 48.7 $ (2.1 ) Other Changes in Plan Assets and Benefit Obligations Recognized in OCI Net prior service credit $ — $ — $ (1.3 ) $ — $ (3.6 ) $ — Amortization of prior service cost (credit) 0.4 — 0.2 — (0.3 ) — Total recognized in OCI 0.4 — (1.1 ) — (3.9 ) — Total recognized in net periodic benefit cost (income) and OCI $ 37.6 $ 25.1 $ 23.6 $ 50.0 $ 44.8 $ (2.1 )
Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]	Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation (In millions) U.S. Non-U.S. Total 2017 2016 2017 2016 2017 2016 Projected benefit obligation $ 1,325.6 $ 1,274.2 $ 298.4 $ 249.3 $ 1,624.0 $ 1,523.5 Accumulated benefit obligation 1,286.0 1,238.8 263.6 222.6 1,549.6 1,461.4 Fair value of plan assets 1,109.8 1,086.4 — — 1,109.8 1,086.4
Schedule of Expected Benefit Payments [Table Text Block]	Estimated Expected Future Benefit Payments Reflecting Future Service for the Fiscal Years Ending (In millions) Pension Plans Total Payments U.S. Non-U.S.(1) Benefit Payments Benefit Payments 2018 $ 82.9 $ 8.9 $ 91.8 2019 83.1 8.4 91.5 2020 83.3 8.6 91.9 2021 83.4 8.9 92.3 2022 83.7 9.1 92.8 2023 - 2027 413.2 49.0 462.2 ___________________________________________________________________________________________________________________ (1) Non-U.S. estimated benefit payments for 2018 and future periods have been translated at the applicable December 31, 2017 , exchange rates.
Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Net Funded Status	Funded Status of U.S. Pension Plans (In millions) Underfunded U.S. Qualified Pension Plans(1) Unfunded Pay-As-You-Go U.S. Nonqualified Plans(2) 2017 2016 2017 2016 Projected benefit obligation $ 1,217.1 $ 1,167.9 $ 108.5 $ 106.3 Fair value of plan assets 1,109.8 1,086.4 — — Funded status (PBO basis) $ (107.3 ) $ (81.5 ) $ (108.5 ) $ (106.3 ) Funded Status of Non-U.S. Pension Plans (In millions) Underfunded Non-U.S. Pension Plans(1) Unfunded Pay-As-You-Go Non-U.S. Pension Plans(2) 2017 2016 2017 2016 Projected benefit obligation $ 24.7 $ 19.8 $ 298.4 $ 249.3 Fair value of plan assets 21.5 18.2 — — Funded status (PBO basis) $ (3.2 ) $ (1.6 ) $ (298.4 ) $ (249.3 ) ___________________________________________________________________________________________________________________ (1) Plans intended to be advance-funded. (2) Plans intended to be pay-as-you-go. The following table presents the funded status of Grace's underfunded and unfunded pension plans: December 31, (In millions) 2017 2016 Underfunded defined benefit pension plans $ (110.5 ) $ (83.1 ) Unfunded defined benefit pension plans (391.9 ) (341.2 ) Total underfunded and unfunded defined benefit pension plans (502.4 ) (424.3 ) Pension liabilities included in other current liabilities (15.0 ) (14.4 ) Net funded status $ (517.4 ) $ (438.7 )
Foreign Plan [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Schedule of Allocation of Plan Assets [Table Text Block]	The following table presents the fair value hierarchy for the non-U.S. pension plan assets measured at fair value as of December 31, 2017 and 2016 . Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Common/collective trust funds $ 20.7 $ — $ 20.7 $ — Corporate bonds 0.4 — 0.4 — Insurance contracts and other investments 0.4 — 0.4 — Total Assets $ 21.5 $ — $ 21.5 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Common/collective trust funds $ 17.6 $ — $ 17.6 $ — Corporate bonds 0.3 — 0.3 — Insurance contracts and other investments 0.3 — 0.3 — Total Assets $ 18.2 $ — $ 18.2 $ —
Qualified Plan [Member] | Domestic Plan [Member] | 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, 2017 , and the actual allocation at December 31, 2017 and 2016 , for Grace's U.S. qualified pension plans are as follows: Target Allocation Percentage of Plan Assets December 31, U.S. Qualified Pension Plans Asset Category 2017 2017 2016 U.S. equity securities 10 % 11 % 8 % Non-U.S. equity securities 5 % 5 % 6 % Short-term debt securities 10 % 10 % 4 % Intermediate-term debt securities 32 % 32 % 32 % Long-term debt securities 41 % 40 % 48 % Other investments 2 % 2 % 2 % 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, 2017 and 2016 . Fair Value Measurements at December 31, 2017, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) U.S. equity group trust funds $ 118.8 $ — $ 118.8 $ — Non-U.S. equity group trust funds 56.8 — 56.8 — Corporate and government bond group trust funds—intermediate-term 353.6 — 353.6 — Corporate and government bond group trust funds—long-term 443.4 — 443.4 — Other fixed income group trust funds 25.3 — 25.3 — Common/collective trust funds 92.9 — 92.9 — Annuity and immediate participation contracts 19.0 — 19.0 — Total Assets $ 1,109.8 $ — $ 1,109.8 $ — Fair Value Measurements at December 31, 2016, Using (In millions) Total Quoted Prices in Active Markets for Identical Assets or Liabilities Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) U.S. equity group trust funds $ 91.5 $ — $ 91.5 $ — Non-U.S. equity group trust funds 62.6 — 62.6 — Corporate bond group trust funds—intermediate-term 342.6 — 342.6 — Corporate bond group trust funds—long-term 521.5 — 521.5 — Other fixed income group trust funds 22.4 — 22.4 — Common/collective trust funds 27.4 — 27.4 — Annuity and immediate participation contracts 18.4 — 18.4 — Total Assets $ 1,086.4 $ — $ 1,086.4 $ —
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, 2017 , and the actual allocation at December 31, 2017 and 2016 , for the Canadian pension plan are as follows: Target Allocation Percentage of Plan Assets December 31, Canadian Pension Plan Asset Category 2017 2017 2016 Equity securities 28 % 28 % 28 % Bonds 58 % 58 % 57 % Other investments 14 % 14 % 15 % Total 100 % 100 % 100 %

Other Balance Sheet Accounts (T

Other Balance Sheet Accounts (Tables)	12 Months Ended
	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Schedule of other balance sheet accounts	December 31, (In millions) 2017 2016 Other Current Liabilities Accrued compensation $ 60.7 $ 49.6 Environmental contingencies 23.5 32.5 Deferred revenue 19.5 27.2 Accrued interest 16.5 16.2 Pension liabilities 15.0 14.4 Income taxes payable 12.2 5.7 Other accrued liabilities 70.4 63.3 $ 217.8 $ 208.9 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) 2017 2016 Other Liabilities Environmental contingencies $ 46.8 $ 33.8 Liability to unconsolidated affiliate 32.7 27.0 Fair value of currency and interest rate contracts 22.7 3.2 Deferred revenue 14.9 2.3 Asset retirement obligation 10.4 10.2 Deferred income taxes 8.2 2.8 Postemployment liability 5.2 7.2 Other noncurrent liabilities 28.4 40.2 $ 169.3 $ 126.7

Restructuring Expenses and Re39

Restructuring Expenses and Related Asset Impairments (Tables)	12 Months Ended
	Dec. 31, 2017
Restructuring and Related Activities [Abstract]
Schedule of restructuring expenses and related asset impairments	Year Ended December 31, (In millions) 2017 2016 2015 Catalysts Technologies $ 3.7 $ 3.4 $ 4.8 Materials Technologies (0.1 ) 15.1 0.8 Corporate 7.9 5.8 5.7 Total restructuring expenses $ 11.5 $ 24.3 $ 11.3
Schedule of restructuring liability	(In millions) Total Balance, December 31, 2014 $ 2.1 Accruals for severance and other costs 11.3 Payments (5.6 ) Currency translation adjustments and other (0.2 ) Balance, December 31, 2015 $ 7.6 Accruals for severance and other costs 17.8 Payments (16.0 ) Currency translation adjustments and other 0.2 Balance, December 31, 2016 $ 9.6 Accruals for severance and other costs 11.4 Payments (14.4 ) Currency translation adjustments and other 0.1 Balance, December 31, 2017 $ 6.7

Other Expense, net (Tables)

Other Expense, net (Tables)	12 Months Ended
	Dec. 31, 2017
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) 2017 2016 2015 Business interruption insurance recoveries $ (26.6 ) $ — $ — Accounts receivable reserve—Venezuela 10.0 — — Currency transaction effects 5.0 (1.0 ) (1.5 ) Third-party acquisition-related costs 2.9 2.5 — Net (gain) loss on sales of investments and disposals of assets 1.6 (1.4 ) (10.6 ) Chapter 11 expenses, net 1.4 3.4 5.1 Loss on early extinguishment of debt — 11.1 — Other miscellaneous expense (income) (2.7 ) (1.3 ) (6.8 ) Total other (income) expense, net $ (8.4 ) $ 13.3 $ (13.8 )

Other Comprehensive Income (L41

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 , and 2015 : Year Ended December 31, 2017 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (2.3 ) $ 0.8 $ (1.5 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.4 (0.1 ) 0.3 Net deferred actuarial gain (loss) arising during period (0.1 ) — (0.1 ) Benefit plans, net (2.0 ) 0.7 (1.3 ) Currency translation adjustments(1) (23.1 ) (2.9 ) (26.0 ) Gain (loss) from hedging activities 2.9 (2.1 ) 0.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (22.2 ) $ (4.3 ) $ (26.5 ) ___________________________________________________________________________________________________________________ (1) In the 2017 third quarter, Grace recorded an out-of-period adjustment to recognize the accumulated deferred tax liability for its euro loan net investment hedge (see Note 6). The correction resulted in a reduction in deferred tax assets and a charge to "other comprehensive income (loss)" of $16.9 million . Grace has assessed the impact of this error and concluded that it was not material to any prior-period and the impact of correcting the error in 2017 is not material. Year Ended December 31, 2016 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (2.4 ) $ 0.9 $ (1.5 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.5 (0.2 ) 0.3 Net prior service credit arising during period 1.4 (0.5 ) 0.9 Loss on curtailment of postretirement plans (0.5 ) 0.2 (0.3 ) Benefit plans, net (1.0 ) 0.4 (0.6 ) Currency translation adjustments (1.8 ) — (1.8 ) Gain (loss) from hedging activities 0.6 (0.3 ) 0.3 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (2.2 ) $ 0.1 $ (2.1 ) Year Ended December 31, 2015 Pre-Tax Amount Tax Benefit/ (Expense) After-Tax Amount Defined benefit pension and other postretirement plans: Amortization of net prior service credit included in net periodic benefit cost $ (3.1 ) $ 1.0 $ (2.1 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.7 (0.2 ) 0.5 Net prior service credit arising during period 5.7 (1.9 ) 3.8 Net deferred actuarial gain (loss) arising during period (0.4 ) 0.1 (0.3 ) Loss on curtailment of postretirement plans (4.5 ) 1.6 (2.9 ) Benefit plans, net (1.6 ) 0.6 (1.0 ) Currency translation adjustments (43.3 ) — (43.3 ) Gain (loss) from hedging activities 2.1 (0.8 ) 1.3 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (42.8 ) $ (0.2 ) $ (43.0 ) T
Schedule of components of accumulated other comprehensive loss	e following table presents the changes in accumulated other comprehensive income (loss), net of tax, for the years ended December 31, 2017 , 2016 , and 2015 : Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Balance, December 31, 2014 $ 4.0 $ (22.8 ) $ (5.0 ) $ (23.8 ) Other comprehensive income (loss) before reclassifications 3.5 (43.3 ) 0.6 (39.2 ) Amounts reclassified from accumulated other comprehensive income (loss) (4.5 ) — 0.7 (3.8 ) Net current-period other comprehensive income (loss) (1.0 ) (43.3 ) 1.3 (43.0 ) Balance, December 31, 2015 $ 3.0 $ (66.1 ) $ (3.7 ) $ (66.8 ) Other comprehensive income (loss) before reclassifications 0.9 (1.8 ) (1.8 ) (2.7 ) Amounts reclassified from accumulated other comprehensive income (loss) (1.5 ) — 2.1 0.6 Net current-period other comprehensive income (loss) (0.6 ) (1.8 ) 0.3 (2.1 ) Distribution of GCP (0.2 ) 135.5 — 135.3 Balance, December 31, 2016 $ 2.2 $ 67.6 $ (3.4 ) $ 66.4 Other comprehensive income (loss) before reclassifications (0.1 ) (26.0 ) (2.7 ) (28.8 ) Amounts reclassified from accumulated other comprehensive income (loss) (1.2 ) — 3.5 2.3 Net current-period other comprehensive income (loss) (1.3 ) (26.0 ) 0.8 (26.5 ) Balance, December 31, 2017 $ 0.9 $ 41.6 $ (2.6 ) $ 39.9 G

Shareholders' Equity (Deficit)

Shareholders' Equity (Deficit) (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 , 2016 , and 2015 : Balance of outstanding shares, December 31, 2014 72,922,565 Stock options exercised 728,408 Shares issued 9,378 Shares forfeited (3,120 ) Shares repurchased (3,123,716 ) Balance of outstanding shares, December 31, 2015 70,533,515 Stock options exercised 745,938 Shares issued 110,953 Shares forfeited (305,678 ) Shares repurchased (2,775,297 ) Balance of outstanding shares, December 31, 2016 68,309,431 Stock options exercised 386,300 Shares issued 49,897 Shares forfeited through net share exercise (29,783 ) Shares repurchased (935,435 ) Balance of outstanding shares, December 31, 2017 67,780,410

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of information relating to options	The following table sets forth information relating to such options during 2017 , 2016 , and 2015 . Stock Option Activity Number Of Shares Average Exercise Price Weighted- Average Grant Date Fair Value Balance, December 31, 2014 2,523,790 $ 55.77 Options exercised (728,408 ) 36.85 Options forfeited (25,000 ) 92.57 Options terminated (500 ) 100.29 Options granted 550,805 77.31 $ 19.28 Balance, December 31, 2015 2,320,687 71.01 Options exercised (745,938 ) 36.97 Options forfeited (9,458 ) 73.40 Options terminated (2,426 ) 67.06 Options granted 377,920 68.32 12.90 Balance, December 31, 2016 1,940,785 66.83 Options exercised (386,300 ) 45.21 Options forfeited (34,545 ) 72.97 Options terminated (23,320 ) 75.60 Options granted 316,830 71.37 13.00 Balance, December 31, 2017 1,813,450
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, 2017 . Stock Option Activity Number Of Shares Weighted- Average Grant Date Fair Value Nonvested options outstanding at beginning of year 878,031 $ 17.76 Granted 316,830 13.00 Vested (417,969 ) 18.78 Forfeited (57,865 ) 18.09 Nonvested options outstanding at end of year 719,027
Schedule of stock options outstanding and exercisable by exercise price range	A summary of our stock options outstanding and exercisable at December 31, 2017 , follows: Exercise Price Range Number Outstanding Number Exercisable Outstanding Weighted- Average Remaining Contractual Life (Years) Exercisable Weighted- Average Exercise Price $60 - $70 586,054 350,469 2.02 63.90 $70 - $80 1,200,806 724,000 2.48 75.97 $80 - $90 26,590 19,954 1.16 80.76 1,813,450 1,094,423
Schedule of the assumptions used for estimating the fair value of stock options granted during the period	The following summarizes the assumptions used for estimating the fair value of stock options granted during 2017 , 2016 and 2015 , respectively. 2017 2016 2015 Expected volatility 24.7% - 25.1% 26.2% - 27.5% 23.0% - 27.2% Weighted average expected volatility 24.9% 26.6% 24.5% Expected term 3.00 - 4.00 years 3.00 - 4.00 years 3.00 - 4.00 years Risk-free rate 1.66% 1.01% 1.30% Dividend yield 1.2% 1.0% —%

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2017
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. (In millions, except per share amounts) 2017 2016 2015 Numerators Income (loss) from continuing operations attributable to W. R. Grace & Co. shareholders $ 11.2 $ 107.0 $ 124.0 Income (loss) from discontinued operations, net of income taxes — (12.9 ) 20.2 Net income (loss) attributable to W. R. Grace & Co. shareholders $ 11.2 $ 94.1 $ 144.2 Denominators Weighted average common shares—basic calculation 68.1 70.1 72.0 Dilutive effect of employee stock options 0.1 0.4 0.6 Weighted average common shares—diluted calculation 68.2 70.5 72.6 Basic earnings per share attributable to W. R. Grace & Co. shareholders Income (loss) from continuing operations $ 0.16 $ 1.53 $ 1.72 Income (loss) from discontinued operations, net of income taxes — (0.19 ) 0.28 Net income (loss) $ 0.16 $ 1.34 $ 2.00 Diluted earnings per share attributable to W. R. Grace & Co. shareholders Income (loss) from continuing operations $ 0.16 $ 1.52 $ 1.71 Income (loss) from discontinued operations, net of income taxes — (0.19 ) 0.28 Net income (loss) $ 0.16 $ 1.33 $ 1.99

Operating Segment Information (

Operating Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of operating segment data	Year Ended December 31, (In millions) 2017 2016 2015 Net Sales Catalysts Technologies $ 1,276.5 $ 1,163.7 $ 1,162.1 Materials Technologies 440.0 434.9 466.1 Total $ 1,716.5 $ 1,598.6 $ 1,628.2 Adjusted EBIT Catalysts Technologies segment operating income $ 395.4 $ 367.8 $ 347.3 Materials Technologies segment operating income 100.6 104.0 96.9 Corporate costs (69.0 ) (59.4 ) (79.9 ) Gain on termination and curtailment of postretirement plans related to current businesses — 0.2 1.9 Certain pension costs (13.0 ) (12.3 ) (20.4 ) Total $ 414.0 $ 400.3 $ 345.8 Depreciation and Amortization Catalysts Technologies $ 87.1 $ 77.4 $ 68.1 Materials Technologies 19.6 19.5 23.2 Corporate 4.8 3.4 7.9 Total $ 111.5 $ 100.3 $ 99.2 Capital Expenditures Catalysts Technologies $ 100.9 $ 84.9 $ 66.3 Materials Technologies 20.9 24.0 24.6 Corporate 3.4 8.0 27.9 Total $ 125.2 $ 116.9 $ 118.8 Total Assets Catalysts Technologies $ 1,757.1 $ 1,675.1 $ 1,390.8 Materials Technologies 326.8 313.1 333.4 Corporate 823.1 923.6 1,051.0 Assets of discontinued operations — — 870.5 Total $ 2,907.0 $ 2,911.8 $ 3,645.7
Schedule of reconciliation of operating segment data to financial statements	Grace Adjusted EBIT for the years ended December 31, 2017 , 2016 and 2015 is reconciled below to income from continuing operations before income taxes presented in the accompanying Consolidated Statements of Operations. Year Ended December 31, (In millions) 2017 2016 2015 Grace Adjusted EBIT $ 414.0 $ 400.3 $ 345.8 Pension MTM adjustment and other related costs, net (51.1 ) (60.3 ) (30.5 ) Costs related to legacy product, environmental and other claims (30.8 ) (35.4 ) (6.1 ) Restructuring and repositioning expenses (26.7 ) (38.6 ) (20.4 ) Accounts receivable reserve—Venezuela (10.0 ) — — Third-party acquisition-related costs (2.9 ) (2.5 ) — Income and expense items related to divested businesses (2.3 ) 0.1 1.5 Loss on early extinguishment of debt — (11.1 ) — Amortization of acquired inventory fair value adjustment — (8.0 ) — Gain (loss) on sale of product line — 1.7 — Gain on termination and curtailment of postretirement plans related to divested businesses — 0.3 2.6 Interest expense, net (78.5 ) (80.5 ) (99.1 ) Net income (loss) attributable to noncontrolling interests (0.8 ) — (0.1 ) Income (loss) from continuing operations before income taxes $ 210.9 $ 166.0 $ 193.7
Similar products within each operating segment	The table below presents sales of similar products within each reportable segment. Year Ended December 31, (In millions) 2017 2016 2015 Catalysts Technologies: Refining catalysts $ 758.1 $ 724.9 $ 764.5 Polyolefin and chemical catalysts 518.4 438.8 397.6 Total $ 1,276.5 $ 1,163.7 $ 1,162.1 Materials Technologies: Coatings $ 142.2 $ 136.5 $ 133.6 Consumer/Pharma 123.3 121.9 125.1 Chemical process 153.5 142.6 137.0 Other 21.0 33.9 70.4 Total $ 440.0 $ 434.9 $ 466.1
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 customer location. Year Ended December 31, (In millions) 2017 2016 2015 Net Sales United States $ 437.3 $ 446.2 $ 444.7 Canada 48.7 44.5 45.3 Total North America 486.0 490.7 490.0 Europe Middle East Africa 667.7 647.8 621.2 Asia Pacific 459.8 348.9 390.9 Latin America 103.0 111.2 126.1 Total $ 1,716.5 $ 1,598.6 $ 1,628.2 Long-Lived Assets(1) United States $ 599.8 $ 564.5 $ 464.1 Canada 15.5 13.9 13.0 Total North America 615.3 578.4 477.1 Germany 142.2 109.7 110.9 Rest of Europe Middle East Africa 45.3 39.5 17.4 Total Europe Middle East Africa 187.5 149.2 128.3 Asia Pacific 21.1 21.5 25.9 Latin America 7.9 7.5 5.5 Total $ 831.8 $ 756.6 $ 636.8 ___________________________________________________________________________________________________________________ (1) Long-lived assets include properties and equipment and the noncurrent asset related to a planned hydroprocessing catalyst plant to be transferred to ART upon completion. (See Note 18.)

Unconsolidated Affiliate Uncons

Unconsolidated Affiliate Unconsolidated Affiliate (Tables)	12 Months Ended
	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Summary of financial information of equity method investee	The following summary presents ART's assets, liabilities and results of operations. December 31, (In millions) 2017 2016 Summary Balance Sheet information: Current assets $ 239.8 $ 249.2 Noncurrent assets 91.5 84.8 Total assets $ 331.3 $ 334.0 Current liabilities $ 82.4 $ 102.0 Noncurrent liabilities 0.3 0.3 Total liabilities $ 82.7 $ 102.3 Year Ended December 31, (In millions) 2017 2016 2015 Summary Statement of Operations information: Net sales $ 447.3 $ 388.9 $ 415.3 Costs and expenses applicable to net sales 379.8 322.1 366.6 Income before income taxes 53.6 60.8 42.8 Net income 52.1 59.3 41.1
Summary of related party transactions	The table below presents summary financial data related to transactions between Grace and ART. Year Ended December 31, (In millions) 2017 2016 2015 Product manufactured for ART $ 213.8 $ 210.4 $ 258.9 Mark-up on product manufactured for ART included as a reduction of Grace's cost of goods sold 4.2 4.2 5.1 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 41.7 33.8 31.6 The table below lists Grace balances related to ART. December 31, (in millions) 2017 2016 Accounts receivable $ 20.1 $ 14.9 Noncurrent asset 32.7 27.0 Accounts payable 22.3 28.7 Debt payable within one year 8.6 7.6 Debt payable after one year 33.8 31.9 Noncurrent liability 32.7 27.0

Quarterly Summary and Statist47

Quarterly Summary and Statistical Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Summary and Statistical Information (Unaudited)	(In millions, except per share amounts) March 31 June 30 September 30 December 31(3) 2017 Net sales $ 398.0 $ 429.5 $ 429.5 $ 459.5 Gross profit 153.2 169.3 173.3 167.5 Net income (loss) 42.9 43.5 47.1 (123.1 ) Net income (loss) attributable to W. R. Grace & Co. shareholders 42.9 43.9 47.4 (123.0 ) Net income (loss) per share:(1) Basic earnings (loss) per share: Net income (loss) $ 0.63 $ 0.64 $ 0.70 $ (1.81 ) Diluted earnings (loss) per share: Net income (loss) 0.63 0.64 0.70 (1.81 ) Dividends declared per share 0.21 0.21 0.21 0.21 Market price of common stock:(2) High $ 74.63 $ 72.72 $ 73.77 $ 77.37 Low 67.54 67.12 65.84 69.37 Close 69.71 72.01 72.15 70.13 ___________________________________________________________________________________________________________________ (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) Principal market: New York Stock Exchange. (3) Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017. (In millions, except per share amounts) March 31 June 30 September 30 December 31(5) 2016 Net sales $ 362.8 $ 390.5 $ 404.5 $ 440.8 Gross profit 152.7 173.2 168.2 161.8 Net income (loss) 0.3 38.5 39.7 15.6 Net income (loss) attributable to W. R. Grace & Co. shareholders 0.5 38.7 39.6 15.3 Net income (loss) per share:(1) Basic earnings (loss) per share: Net income (loss) $ 0.01 $ 0.55 $ 0.56 $ 0.22 Diluted earnings (loss) per share: Net income (loss) 0.01 0.55 0.56 0.22 Dividends declared per share — 0.17 0.17 0.17 Market price of common stock:(2)(3) High $ 98.15 (4) $ 80.39 $ 80.56 $ 74.38 Low 63.84 70.59 71.47 63.37 Close 71.18 73.21 73.80 67.64 ___________________________________________________________________________________________________________________ (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) Principal market: New York Stock Exchange. (3) Share prices subsequent to February 3, 2016, reflect the Separation and exclude separate trading of GCP common stock. (4) Price is a pre-Separation market price of common stock. (5) Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisition [Line Items]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	(In millions) Inventories $ 30.2 Properties and equipment 95.0 Goodwill 63.8 Intangible assets 61.6 Net assets acquired $ 250.6
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination [Table Text Block]	The table below presents the intangible assets acquired as part of the acquisition of the assets of BASF's polyolefin catalysts business and the periods over which they will be amortized. Amount (In millions) Weighted Average Amortization Period (in years) Customer Lists $ 39.9 20.0 Trademarks 13.4 20.0 Technology 8.3 20.0 Total $ 61.6 20.0

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	GCP’s historical financial results through the Distribution Date and other effects of the Separation are presented as discontinued operations as summarized below: Year Ended December 31, (In millions) 2016 2015 Net sales $ 99.6 $ 1,423.3 Cost of goods sold 62.6 907.5 Gross profit 37.0 515.8 Selling, general and administrative expenses 21.6 251.2 Research and development expenses 1.7 22.5 Loss in Venezuela — 59.6 Repositioning expenses 22.0 55.1 Interest expense and related financing costs 0.7 1.5 Other expense, net 3.9 9.9 Total costs and expenses 49.9 399.8 (Loss) Income from discontinued operations before income taxes (12.9 ) 116.0 Benefit from (provision for) income taxes 0.1 (95.0 ) (Loss) Income from discontinued operations after income taxes (12.8 ) 21.0 Less: Net income attributable to noncontrolling interests (0.1 ) (0.8 ) Net (loss) income from discontinued operations $ (12.9 ) $ 20.2

Basis of Presentation and Sum50

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Feb. 03, 2016shares
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of Reportable Segments | segment	2
Number of Shares Distributed Per Each Share of Stock Held at Close | shares				1
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	3 years
Minimum | Furniture and fixtures [Member]
Long-lived assets
Long lived assets, estimated useful life	5 years
Maximum
Long-lived assets
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	10 years
Maximum | Furniture and fixtures [Member]
Long-lived assets
Long lived assets, estimated useful life	10 years

Basis of Presentation and Sum51

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies Recently Adopted Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash and cash equivalents	$ 10.7	$ 10
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, New Rate	21.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 143	$ 0	$ 0
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	120.1
Income tax expense, repatriation of foreign earnings	37.4
Income tax expense, state and foreign taxes on unremitted earnings	4.9
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	19.1
Deferred Tax Asset Deferred Federal Credits [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	17.4
State and Local Jurisdiction [Member] | Net Operating Loss [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 2

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 48.8	$ 57.7
In process	33	33.4
Finished products	124.7	115.8
Other	24.4	21.1
Total inventories	$ 230.9	$ 228

Properties and Equipment (Detai

Properties and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Properties and Equipment
Properties and equipment, gross	$ 2,262.5	$ 2,057.1
Accumulated depreciation and amortization	(1,463.4)	(1,327.5)
Interest Costs Capitalized	1.5	1.3	$ 1
Depreciation and lease amortization expense related to properties and equipment	111.5	100.3	99.2
Rental expense for operating leases	11.3	10	10.6
Property, Plant and Equipment [Member]
Properties and Equipment
Depreciation and lease amortization expense related to properties and equipment	96.1	85.7	$ 81.8
Land
Properties and Equipment
Properties and equipment, gross	14.2	10
Building [Member]
Properties and Equipment
Properties and equipment, gross	404.5	375.4
Information technology and equipment [Member]
Properties and Equipment
Properties and equipment, gross	136.6	125.3
Machinery, equipment and other
Properties and Equipment
Properties and equipment, gross	1,571.8	1,445.8
Projects under construction
Properties and Equipment
Properties and equipment, gross	$ 135.4	$ 100.6

Properties and Equipment (Det54

Properties and Equipment (Details 2) $ in Millions	Dec. 31, 2017USD ($)
Property, Plant and Equipment [Abstract]
2,018	$ 10.4
2,019	7.3
2,020	5.5
2,021	3
2,022	2.8
Thereafter	39.3
Total	$ 68.3

Goodwill and Other Intangible55

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in goodwill balances
Balance at the beginning of the period	$ 394.2	$ 336.5
Goodwill, Acquired During Period	2.4	63.8
Foreign currency translation	5.8	(3.6)
Write-off related to exited product lines		(2.5)
Balance at the end of the period	402.4	394.2
Grace Catalysts Technologies
Changes in goodwill balances
Balance at the beginning of the period	353.5	292.7
Goodwill, Acquired During Period	0	63.8
Foreign currency translation	4.2	(3)
Write-off related to exited product lines		0
Balance at the end of the period	357.7	353.5
Grace Materials Technologies
Changes in goodwill balances
Balance at the beginning of the period	40.7	43.8
Goodwill, Acquired During Period	2.4	0
Foreign currency translation	1.6	(0.6)
Write-off related to exited product lines		(2.5)
Balance at the end of the period	$ 44.7	$ 40.7

Goodwill and Other Intangible56

Goodwill and Other Intangible Assets (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, net book value	$ 255.4	$ 269.1
Net book value of other intangible assets
Gross carrying amount	312	332.9
Accumulated Amortization	56.6	63.8
Amortization of intangible assets	15.4	13.9	$ 16.2
Estimated Amortization Expenses
2,018	15.4
2,019	15.4
2,020	15.1
2,021	14.9
2,022	14.8
Thereafter	179.8
Total estimated amortization expenses	255.4
Technology
Net book value of other intangible assets
Gross carrying amount	214.7	222.3
Accumulated Amortization	41.5	38.9
Customer Lists [Member]
Net book value of other intangible assets
Gross carrying amount	55.8	69.6
Accumulated Amortization	8.8	20.3
Trademarks [Member]
Net book value of other intangible assets
Gross carrying amount	25.5	25.3
Accumulated Amortization	2.6	1.5
Other Intangible Assets [Member]
Net book value of other intangible assets
Gross carrying amount	16	15.7
Accumulated Amortization	$ 3.7	$ 3.1

Debt (Details)

Debt (Details) € in Millions		Jan. 27, 2016USD ($)	Jan. 30, 2015USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016EUR (€)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2017USD ($)
Notes Payable, Related Parties						$ 39,500,000			$ 42,400,000
Deferred payment obligations						30,000,000			0
Debt payable within one year						76,500,000			20,100,000
Debt payable after one year						$ 1,507,600,000			$ 1,523,800,000
Full-year weighted average interest rates on total debt						4.60%		4.70%	4.70%
2,018									$ 20,100,000
2,019									8,700,000
2,020									7,400,000
2,021									1,198,200,000
2,022									5,000,000
Thereafter									304,500,000
Total debt						$ 1,584,100,000			1,543,900,000
Payments for Repurchase of Warrants			$ 490,000,000
Distribution to Grace from GCP		$ 750,000,000
Amount of distribution from GCP dividend used to pay down Grace debt						600,000,000
Repayments of Debt				$ 143,900,000		633,000,000	$ 50,000,000
Loss on early extinguishment of debt				$ 0		(11,100,000)	$ 0
Debt Instrument, Price as Percent of Par Value				100.00%
Proceeds from Debt, Net of Issuance Costs				$ 985,500,000
Cash paid to settle deferred payment obligation				$ 632,000,000
Debt Instrument, Redemption Price, Percentage				100.00%
Debt Instrument, Required Redemption Price, Percentage				101.00%
Final Judgment for Payment, Event of Debt Default									75,000,000
Debt Instrument, Event of Default, Percent Principal Aggregate Outstanding				25.00%
Term Loan B (USD) [Member]
Total debt	[1]					$ 402,700,000			404,100,000
Senior Secured Credit Facilities to Fund Emergence									700,000,000
Debt Instrument, Basis Spread on Variable Rate				2.00%	2.00%	2.00%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 5,700,000			4,300,000
Term Loan B (EUR) [Member]
Total debt	[1]					$ 82,500,000			94,000,000
Senior Secured Credit Facilities to Fund Emergence | €								€ 150
Debt Instrument, Basis Spread on Variable Rate				2.25%	2.25%	2.25%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 1,300,000			1,000,000
Revolving Credit Facility [Member]
Senior Secured Credit Facilities to Fund Emergence									300,000,000
Long-term Line of Credit									0
Letters of Credit Outstanding, Amount									262,800,000
Debt Instrument, Basis Spread on Variable Rate				1.75%	1.75%	1.75%
Delayed Draw Term Loan B [Member]
Senior Secured Credit Facilities to Fund Emergence			$ 250,000,000
Other Debt Obligations [Member]
Total debt	[2]					$ 40,700,000			12,700,000
Term Loan B (EUR) [Member]
Repayments of Debt | €					€ 67.3
Term Loan B (USD) [Member]
Repayments of Debt						$ 526,900,000
Senior Notes [Member]
Senior Notes									1,000,000,000
Debt Instrument, Basis Spread on Variable Rate				0.50%	0.50%	0.50%
Senior Notes, Due 2021 [Member]
Total debt	[3]					$ 692,700,000			694,200,000
Senior Notes									$ 700,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.125%		5.125%	5.125%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 7,300,000			$ 5,800,000
Senior Notes, Due 2024 [Member]
Total debt	[3]					$ 296,000,000			296,500,000
Senior Notes									$ 300,000,000
Debt Instrument, Interest Rate, Stated Percentage						5.625%		5.625%	5.625%
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net						$ 4,000,000			$ 3,500,000
Minimum | Term Loan B (USD) [Member]
Debt Instrument, Interest Rate, Stated Percentage						0.75%		0.75%	0.75%
Minimum | Term Loan B (EUR) [Member]
Debt Instrument, Interest Rate, Stated Percentage						0.75%		0.75%	0.75%
[1]	(2)Carrying amounts are net of unamortized debt issuance costs and discounts of $4.3 million and $1.0 million at December 31, 2017, and $5.7 million and $1.3 million as of December 31, 2016, related to the U.S. dollar term loan and euro term loan, respectively.
[2]	Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries.
[3]	(1)Carrying amounts are net of unamortized debt issuance costs of $5.8 million and $3.5 million at December 31, 2017, and $7.3 million and $4.0 million as of December 31, 2016, related to the 5.125% senior notes due 2021 and 5.625% senior notes due 2024, respectively.

Fair Value Measurements and R58

Fair Value Measurements and Risk (Details) $ in Millions		12 Months Ended
		Dec. 31, 2017USD ($)country	Dec. 31, 2016USD ($)	Feb. 03, 2015USD ($)
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		$ 1,543.9	$ 1,584.1
Number of countries where company does business, greater than | country		60
Number of Currencies Used		30
Maximum Maturity of Foreign Currency Derivatives		36 months
Derivative, Fixed Interest Rate				2.393%
Assets
Total Assets		$ 3.1	8.8
Liabilities
Total Liabilities		25.6	6.9
Recurring basis
Assets
Currency derivatives		3.1	8.8
Total Assets		3.1	8.8
Liabilities
Currency derivatives		23.8	0.9
Interest rate derivatives		1.8	6
Total Liabilities		25.6	6.9
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Currency derivatives		3.1	8.8
Total Assets		3.1	8.8
Liabilities
Currency derivatives		23.8	0.9
Interest rate derivatives		1.8	6
Total Liabilities		25.6	6.9
Foreign Exchange Forward [Member]
Items measured at Fair Value on a Recurring Basis
Derivative, Notional Amount		230.2
Interest Rate Swap [Member]
Items measured at Fair Value on a Recurring Basis
Derivative, Notional Amount				$ 250
Senior Notes, Due 2021 [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)	[1]	694.2	692.7
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		$ 5.8	$ 7.3
Debt Instrument, Interest Rate, Stated Percentage		5.125%	5.125%
Senior Notes, Due 2024 [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)	[1]	$ 296.5	$ 296
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		$ 3.5	$ 4
Debt Instrument, Interest Rate, Stated Percentage		5.625%	5.625%
Term Loan B (USD) [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)	[2]	$ 404.1	$ 402.7
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		4.3	5.7
Term Loan B (EUR) [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)	[2]	94	82.5
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net		1	1.3
Reported Value Measurement [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		1,543.9	1,584.1
Reported Value Measurement [Member] | Other Debt Obligations [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		55.1	110.2
Estimate of Fair Value Measurement [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		1,608.5	1,633.2
Estimate of Fair Value Measurement [Member] | Senior Notes, Due 2021 [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		728.7	721.3
Estimate of Fair Value Measurement [Member] | Senior Notes, Due 2024 [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		321.3	311.5
Estimate of Fair Value Measurement [Member] | Term Loan B (USD) [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		409.7	408.2
Estimate of Fair Value Measurement [Member] | Term Loan B (EUR) [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		93.7	82
Estimate of Fair Value Measurement [Member] | Other Debt Obligations [Member]
Items measured at Fair Value on a Recurring Basis
Other borrowings (not subject to compromise)		55.1	110.2
Other current assets | Designated as Hedging Instrument [Member]
Assets
Currency derivatives		2.7	4
Other current assets | Not Designated as Hedging Instrument [Member]
Assets
Currency derivatives		$ 0.4	$ 0.8
[1]	(1)Carrying amounts are net of unamortized debt issuance costs of $5.8 million and $3.5 million at December 31, 2017, and $7.3 million and $4.0 million as of December 31, 2016, related to the 5.125% senior notes due 2021 and 5.625% senior notes due 2024, respectively.
[2]	(2)Carrying amounts are net of unamortized debt issuance costs and discounts of $4.3 million and $1.0 million at December 31, 2017, and $5.7 million and $1.3 million as of December 31, 2016, related to the U.S. dollar term loan and euro term loan, respectively.

Fair Value Measurements and R59

Fair Value Measurements and Risk (Details 2) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair values of derivative instruments
Asset Derivatives	$ 3.1	$ 8.8
Liability Derivatives	25.6	6.9
Not Designated as Hedging Instrument [Member] | Other current assets
Fair values of derivative instruments
Asset Derivatives, Currency contracts	0.4	0.8
Not Designated as Hedging Instrument [Member] | Other current liabilities
Fair values of derivative instruments
Foreign Currency Contracts, Liability, Fair Value Disclosure	0.2	0.9
Derivatives designated as hedging instruments under ASC 815 | Other current assets
Fair values of derivative instruments
Asset Derivatives, Currency contracts	2.7	4
Interest Rate Derivative Assets, at Fair Value	0	0
Derivatives designated as hedging instruments under ASC 815 | Other assets
Fair values of derivative instruments
Asset Derivatives, Currency contracts	0	4
Interest Rate Derivative Assets, at Fair Value	0	0
Derivatives designated as hedging instruments under ASC 815 | Other current liabilities
Fair values of derivative instruments
Foreign Currency Contracts, Liability, Fair Value Disclosure	1.4	0
Interest Rate Derivative Liabilities, at Fair Value	1.3	2.8
Derivatives designated as hedging instruments under ASC 815 | Other liabilities
Fair values of derivative instruments
Foreign Currency Contracts, Liability, Fair Value Disclosure	22.2	0
Interest Rate Derivative Liabilities, at Fair Value	$ 0.5	$ 3.2

Fair Value Measurements and R60

Fair Value Measurements and Risk (Details 3) € in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)		Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017EUR (€)	Dec. 31, 2017USD ($)	Feb. 03, 2015
Gains and losses on derivative instruments
Interest and Debt Expense	$ 79.5		$ 81.5	$ 99.4
Other (income) expense, net	8.4		(13.3)	13.8
Derivative, Fixed Interest Rate							2.393%
Deferred intercompany royalties designated as hedging instrument | €					€ 33.7
Currency contracts
Gains and losses on derivative instruments
Derivative, Notional Amount						$ 230.2
Currency Swap [Member]
Gains and losses on derivative instruments
Derivative, Notional Amount | €					170
Net Investment Hedging [Member]
Gains and losses on derivative instruments
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(21.9)		5.6
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	(17.7)		7.1	18.3
Foreign currency denominated deferred intercompany royalties [Member]
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	(6.5)		2.5
Derivatives in ASC 815 cash flow hedging relationships
Gains and losses on derivative instruments
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(2.7)		(2.3)	(4.2)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(5.6)		(3.3)	(3.1)
Derivatives in ASC 815 cash flow hedging relationships | Interest Rate Contract [Member] | Interest Expense [Member]
Gains and losses on derivative instruments
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	0.9		(2.2)	(5.6)
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(2.7)		(4.1)	(3.8)
Derivatives in ASC 815 cash flow hedging relationships | Currency contracts | Other income (expense)
Gains and losses on derivative instruments
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(3.6)	[1]	(0.1)	1.4
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(2.9)		$ 0.8	$ 0.7
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0.6
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 0.6
Term Loan B (EUR) [Member]
Gains and losses on derivative instruments
Debt, Long-term and Short-term, Combined Amount | €					€ 80.1
[1]	(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.

Fair Value Measurements and R61

Fair Value Measurements and Risk Fair Value Measurement and Risk (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gains and losses on derivative instruments
Reclassification From Accumulated Other Comprehensive Income, Cumulative Changes in Net Gain (Loss) from Hedges, Current Period	$ 0	$ 0	$ 0
Foreign currency denominated debt [Member]
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	(11.2)	4.6
Foreign currency denominated deferred intercompany royalties [Member]
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	(6.5)	2.5
Net Investment Hedging [Member]
Gains and losses on derivative instruments
Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)	(21.9)	5.6
Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments	$ (17.7)	$ 7.1	$ 18.3

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income before income taxes:
Domestic	$ 28.3	$ 72.7	$ 97.1
Foreign	182.6	93.3	96.6
Income (loss) from continuing operations before income taxes	210.9	166	193.7
Provision for income taxes:
Federal-deferred	(144.6)	(11.8)	(35.4)
State and local-current	0.2	(0.7)	4.1
State and local - deferred	(1.7)	(17.7)	(6.4)
Foreign-current	(50.8)	(36.6)	(23.5)
Foreign-deferred	(3.6)	7.8	(8.6)
(Provision for) benefit from income taxes	$ (200.5)	(59)	(69.8)
U.S. federal income tax rate (as a percent)	35.00%
Income tax provision analysis
Tax provision at U.S. federal income tax rate	$ (73.8)	(58.1)	(67.8)
Change in provision resulting from:
Provisional charge related to U.S. tax reform	(143)	0	0
Effect of tax rates in foreign jurisdictions	13.3	6.8	3
Research and development credit	5.1	0	0
Stock option exercises	2.8	6.7	0
Nontaxable income/non-deductible expenses	2.6	2.5	0.9
State and local income taxes, net	(1.8)	(4.7)	(2.9)
U.S. tax on foreign earnings	(1.2)	(0.9)	(1.7)
Decrease (increase) in valuation allowance	(0.3)	(2.5)	1.6
Other	1	(3.8)	(1.1)
(Provision for) benefit from income taxes	(200.5)	(59)	$ (69.8)
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability	120.1
Income tax expense, repatriation of foreign earnings	37.4
Income tax expense, state and foreign taxes on unremitted earnings	4.9
Deferred tax assets:
Federal tax credit carryforwards	269.6	183.2
Pension liabilities	104.8	120.1
U.S. net operating loss carryforwards	89.5	293.6
State net operating loss carryforwards	58.2	50.9
Research and development	22.8	35.4
Prepaid royalties	21.4	20.8
Liability for environmental remediation	16.4	24.6
Reserves and allowances	15.2	31.1
Foreign net operating loss carryforwards	6.6	5.9
Liability for asbestos-related litigation	0	11.1
Other	14.5	29
Total deferred tax assets	619	805.7
Deferred tax liabilities:
Properties and equipment	(32)	(38.5)
Intangible assets	(15.1)	(18.4)
Pension assets	0	(6.1)
Other	(11.3)	(4.7)
Total deferred tax liabilities	(58.4)	(67.7)
Valuation allowance:
Decrease (Increase) in deferred tax assets	158.3
Total valuation allowance	(12.3)	(31.4)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(19.1)
Net deferred tax assets	548.3	706.6
State and Local Jurisdiction [Member]
Valuation allowance:
Total valuation allowance	(9.2)	(11.2)
Domestic Tax Authority [Member]
Valuation allowance:
Total valuation allowance	(0.3)	(17.7)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(19.4)
Foreign Tax Authority [Member]
Valuation allowance:
Total valuation allowance	(2.8)	$ (2.5)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 0.3

Income Taxes (Details 2)

Income Taxes (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	$ 269.6	$ 183.2
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	89.5	293.6
State net operating loss carryforwards	58.2	$ 50.9
Decrease (Increase) in deferred tax assets	158.3
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	19.1
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	19.4
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	(0.3)
Valuation Allowance, Tax Credit Carryforward [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	1,200
Valuation Allowance, Tax Credit Carryforward [Member] | Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	200
Net Operating Loss [Member] | Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	440
Net Operating Loss [Member] | State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Taxable Income Required to Realize DTA, Total	$ 1,500

Income Taxes (Details 3)

Income Taxes (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Resulting in Decrease of Deferred Tax Asset	$ (17.7)
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	17.7
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	0	$ 0
Roll forward of uncertain tax positions
Balance	17.7	18.7	$ 23.1	$ 26.5
Additions for current year tax positions	0.8	6.8	0.1
Additions for prior year tax positions	0.7	0.2	0.8
Reductions for prior year tax positions and reclassifications	$ (2.5)	(0.2)	(1.6)
Reductions for expirations of statute of limitations			(1.5)
Settlements		(3.3)	$ (1.2)
Transferred to GCP upon Separation		$ (7.9)

Pension Plans and Other Postr65

Pension Plans and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans		$ 502.4	$ 424.3
Pension liabilities included in other current liabilities		15	14.4
Net funded status		$ (517.4)	(438.7)
Defined contribution retirement plan
Percentage that the employer contributes of employee contributions under 401(k) plan		100.00%
Maximum percentage of employee compensation match by employer to defined contribution plan		6.00%
Costs related to defined contribution retirement plan		$ 11.5	11.1	$ 10.4
Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status		(517.4)	(438.7)
Defined Benefit Plan, Benefit Obligation		1,648.7	1,543.3	1,477.6
Underfunded Plan [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans		110.5	83.1
Unfunded Plan [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Underfunded and unfunded defined benefit pension plans		391.9	341.2
Domestic Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status		(215.8)	(187.8)
Defined Benefit Plan, Benefit Obligation		$ 1,325.6	$ 1,274.2	1,238.8
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.57%	4.06%
Domestic Plan [Member] | Underfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	[1]	$ (107.3)	$ (81.5)
Defined Benefit Plan, Benefit Obligation	[1]	1,217.1	1,167.9
Domestic Plan [Member] | Unfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	[2]	(108.5)	(106.3)
Defined Benefit Plan, Benefit Obligation	[2]	108.5	106.3
Foreign Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status		(301.6)	(250.9)
Defined Benefit Plan, Benefit Obligation		$ 323.1	$ 269.1	$ 238.8
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		1.84%	1.91%
Foreign Plan [Member] | Underfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	[1]	$ (3.2)	$ (1.6)
Defined Benefit Plan, Benefit Obligation	[1]	24.7	19.8
Foreign Plan [Member] | Unfunded Plan [Member] | Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Net funded status	[2]	(298.4)	(249.3)
Defined Benefit Plan, Benefit Obligation	[2]	$ 298.4	$ 249.3
[1]	(1)Plans intended to be advance-funded.
[2]	Plans intended to be pay-as-you-go.

Pension Plans and Other Postr66

Pension Plans and Other Postretirement Benefit Plans (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in Plan Assets:
Net funded status	$ (517.4)	$ (438.7)
Net Periodic Benefit Cost
Annual mark-to-market adjustment	51.1	60.3	$ 30.5
Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	1,543.3	1,477.6
Service cost	25.5	24.6
Interest cost	46.4	45.6
Amendments		(1.3)
Settlements/curtailments		2.3
Defined Benefit Plan, Benefit Obligation, Business Combination	0.4	0
Actuarial (gain) loss	101.7	102.2
Benefits paid	99	91.4
Currency exchange translation adjustments	(35.2)	11.7
Defined Benefit Plan, Benefit Obligation, Divestiture	(4.8)	0
Benefit obligation at end of year	1,648.7	1,543.3	1,477.6
Change in Plan Assets:
Fair value of plan assets at beginning of year	1,104.6	1,085.9
Actual return on plan assets	114.3	95.1
Employer contributions	17.8	15.9
Settlements		1.3
Benefits paid	(99)	(91.4)
Currency exchange translation adjustments	1.3	0.4
Defined Benefit Plan, Plan Assets, Divestiture	(7.7)	0
Fair value of plan assets at end of year	1,131.3	1,104.6	1,085.9
Net funded status	(517.4)	(438.7)
Amounts recognized in the Consolidated Balance Sheets consist of:
Current liabilities	(15)	(14.4)
Noncurrent liabilities	(502.4)	(424.3)
Net amount recognized	(517.4)	(438.7)
Amounts recognized in Accumulated Other Comprehensive Loss consist of:
Prior service cost (credit)	(4)	(4.4)
Net amount recognized	(4)	(4.4)
Net Periodic Benefit Cost
Service cost	25.5	24.6
Interest cost	46.4	45.6
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Prior service cost that will be amortized from accumulated other comprehensive loss into net periodic benefit cost over the next fiscal year	0.6
Postretirement Benefits Other Than Pensions
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Prior service cost that will be amortized from accumulated other comprehensive loss into net periodic benefit cost over the next fiscal year	1
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	(0.4)
Domestic Plan [Member] | Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	1,274.2	1,238.8
Service cost	17.1	17.8	25.7
Interest cost	42	40.5	55.1
Amendments		(1.3)
Defined Benefit Plan, Benefit Obligation, Business Combination	0	0
Actuarial (gain) loss	88.3	62.3
Benefits paid	91.2	83.9
Defined Benefit Plan, Benefit Obligation, Divestiture	(4.8)	0
Benefit obligation at end of year	1,325.6	1,274.2	1,238.8
Change in Plan Assets:
Fair value of plan assets at beginning of year	1,086.4	1,067.2
Actual return on plan assets	112.7	95.6
Employer contributions	9.6	7.5
Benefits paid	(91.2)	(83.9)
Defined Benefit Plan, Plan Assets, Divestiture	(7.7)
Fair value of plan assets at end of year	1,109.8	1,086.4	1,067.2
Net funded status	(215.8)	(187.8)
Amounts recognized in the Consolidated Balance Sheets consist of:
Current liabilities	(7)	(7.4)
Noncurrent liabilities	(208.8)	(180.4)
Net amount recognized	(215.8)	(187.8)
Amounts recognized in Accumulated Other Comprehensive Loss consist of:
Prior service cost (credit)	(3.9)	(4.3)
Net amount recognized	$ (3.9)	$ (4.3)
Weighted Average Assumptions Used to Determine Benefit Obligations as of the period
Discount rate	3.57%	4.06%
Rate of compensation increase	4.10%	4.10%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Expected return on plan assets	5.50%	5.50%
Rate of compensation increase	4.10%	4.10%
Net Periodic Benefit Cost
Service cost	$ 17.1	$ 17.8	25.7
Interest cost	42	40.5	55.1
Expected return on plan assets	(57.5)	(56.7)	(70.4)
Amortization of prior service cost (credit)	(0.4)	(0.2)	0.3
Annual mark-to-market adjustment	36	23.3	42
Net periodic benefit cost	37.2	24.7	52.7
Less: discontinued operations	0	0	(4)
Net periodic benefit cost (income) from continuing operations	37.2	24.7	48.7
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Net prior service credit		(1.3)	(3.6)
Amortization of prior service cost (credit)	0.4	0.2	(0.3)
Total recognized in other comprehensive (income) loss	0.4	(1.1)	(3.9)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	37.6	23.6	44.8
Foreign Plan [Member] | Pension Plans
Change in Projected Benefit Obligation (PBO):
Benefit obligation at beginning of year	269.1	238.8
Service cost	8.4	6.8	11.7
Interest cost	4.4	5.1	16.1
Amendments		0
Settlements/curtailments		2.3
Defined Benefit Plan, Benefit Obligation, Business Combination	0.4	0
Actuarial (gain) loss	13.4	39.9
Benefits paid	7.8	7.5
Currency exchange translation adjustments	(35.2)	11.7
Defined Benefit Plan, Benefit Obligation, Divestiture	0	0
Benefit obligation at end of year	323.1	269.1	238.8
Change in Plan Assets:
Fair value of plan assets at beginning of year	18.2	18.7
Actual return on plan assets	1.6	(0.5)
Employer contributions	8.2	8.4
Settlements		1.3
Benefits paid	(7.8)	(7.5)
Currency exchange translation adjustments	1.3	0.4
Defined Benefit Plan, Plan Assets, Divestiture		0
Fair value of plan assets at end of year	21.5	18.2	18.7
Net funded status	(301.6)	(250.9)
Amounts recognized in the Consolidated Balance Sheets consist of:
Current liabilities	(8)	(7)
Noncurrent liabilities	(293.6)	(243.9)
Net amount recognized	(301.6)	(250.9)
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	1.84%	1.91%
Rate of compensation increase	2.64%	3.09%
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Expected return on plan assets	4.69%	5.08%
Rate of compensation increase	3.09%	3.09%
Net Periodic Benefit Cost
Service cost	$ 8.4	$ 6.8	11.7
Interest cost	4.4	5.1	16.1
Expected return on plan assets	(0.9)	(1)	(13)
Amortization of prior service cost (credit)			0
Annual mark-to-market adjustment	13.2	40.1	(0.1)
Net curtailment and settlement gain		(1)	0
Net periodic benefit cost	25.1	50	14.7
Less: discontinued operations	0	0	(16.8)
Net periodic benefit cost (income) from continuing operations	25.1	50	(2.1)
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss
Net prior service credit		0
Amortization of prior service cost (credit)			0
Total recognized in other comprehensive (income) loss		0	0
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ 25.1	$ 50	$ (2.1)
Service Cost [Member] | Domestic Plan [Member] | Pension Plans
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Discount rate	4.41%	4.68%
Service Cost [Member] | Foreign Plan [Member] | Pension Plans
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Discount rate	2.09%	2.90%
Interest cost [Member] | Domestic Plan [Member] | Pension Plans
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Discount rate	3.42%	3.38%
Interest cost [Member] | Foreign Plan [Member] | Pension Plans
Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost for Years Ended
Discount rate	1.69%	2.26%

Pension Plans and Other Postr67

Pension Plans and Other Postretirement Benefit Plans (Details 3) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Funded Status of Pension Plans
Net funded status		$ (517.4)	$ (438.7)
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	[1]	91.8
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	[1]	91.5
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	[1]	91.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	[1]	92.3
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	[1]	92.8
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	[1]	462.2
Pension Plans
Funded Status of Pension Plans
Projected benefit obligation		1,648.7	1,543.3	$ 1,477.6
Defined Benefit Plan, Fair Value of Plan Assets		1,131.3	1,104.6	1,085.9
Net funded status		(517.4)	(438.7)
Defined Benefit Plan, Accumulated Benefit Obligation		1,570	1,478
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation		1,624	1,523.5
Accumulated benefit obligation		1,549.6	1,461.4
Fair value of plan assets		$ 1,109.8	$ 1,086.4
Domestic Plan [Member] | Pension Plans
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage		100.00%
Defined Benefit Plan, Actual Plan Asset Allocations		100.00%	100.00%
Funded Status of Pension Plans
Projected benefit obligation		$ 1,325.6	$ 1,274.2	1,238.8
Defined Benefit Plan, Fair Value of Plan Assets		1,109.8	1,086.4	1,067.2
Net funded status		(215.8)	(187.8)
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation		1,325.6	1,274.2
Accumulated benefit obligation		1,286	1,238.8
Fair value of plan assets		1,109.8	$ 1,086.4
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months		82.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Two		83.1
Defined Benefit Plan, Expected Future Benefit Payment, Year Three		83.3
Defined Benefit Plan, Expected Future Benefit Payment, Year Four		83.4
Defined Benefit Plan, Expected Future Benefit Payment, Year Five		83.7
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter		$ 413.2
Total Payments Net of Subsidy
Discount rate		3.57%	4.06%
Percentage of high yield bonds in foreign issuers portfolio		30.00%
Expected return on plan assets		5.50%	5.50%
Average annual returns over one year (as a percent)		11.00%
Average annual returns over three years (as a percent)		6.00%
Average annual returns over five years (as a percent)		6.00%
Average annual returns over ten years (as a percent)		5.00%
Foreign Plan [Member] | Pension Plans
Funded Status of Pension Plans
Projected benefit obligation		$ 323.1	$ 269.1	238.8
Defined Benefit Plan, Fair Value of Plan Assets		21.5	18.2	$ 18.7
Net funded status		(301.6)	(250.9)
Pension Plans with Underfunded or Unfunded Accumulated Benefit Obligation
Projected benefit obligation		298.4	249.3
Accumulated benefit obligation		263.6	$ 222.6
Benefit Payments
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	[1]	8.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	[1]	8.4
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	[1]	8.6
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	[1]	8.9
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	[1]	9.1
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	[1]	$ 49
Total Payments Net of Subsidy
Discount rate		1.84%	1.91%
Expected return on plan assets		4.69%	5.08%
Germany | Pension Plans
Total Payments Net of Subsidy
Discount rate		1.73%
Germany | Foreign Plan [Member] | Pension Plans
Total Payments Net of Subsidy
Percentage of German pension plans to total non-U.S. pension plans		91.00%	92.00%
Unfunded Plan [Member] | Domestic Plan [Member] | Pension Plans
Funded Status of Pension Plans
Projected benefit obligation	[2]	$ 108.5	$ 106.3
Net funded status	[2]	(108.5)	(106.3)
Unfunded Plan [Member] | Foreign Plan [Member] | Pension Plans
Funded Status of Pension Plans
Projected benefit obligation	[2]	298.4	249.3
Net funded status	[2]	(298.4)	(249.3)
Underfunded Plan [Member] | Domestic Plan [Member] | Pension Plans
Funded Status of Pension Plans
Projected benefit obligation	[3]	1,217.1	1,167.9
Defined Benefit Plan, Fair Value of Plan Assets	[3]	1,109.8	1,086.4
Net funded status	[3]	(107.3)	(81.5)
Underfunded Plan [Member] | Foreign Plan [Member] | Pension Plans
Funded Status of Pension Plans
Projected benefit obligation	[3]	24.7	19.8
Defined Benefit Plan, Fair Value of Plan Assets	[3]	21.5	18.2
Net funded status	[3]	$ (3.2)	$ (1.6)
[1]	Non-U.S. estimated benefit payments for 2018 and future periods have been translated at the applicable December 31, 2017, exchange rates.
[2]	Plans intended to be pay-as-you-go.
[3]	(1)Plans intended to be advance-funded.

Pension Plans and Other Postr68

Pension Plans and Other Postretirement Benefit Plans (Details 4) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 1,131.3	$ 1,104.6	$ 1,085.9
Domestic Plan [Member]
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	$ 1,109.8	$ 1,086.4	1,067.2
Expected return on plan assets	5.50%	5.50%
Plan contributions and funding
Defined Benefit Plan, Mandatory Future Employer Contributions, Next Fiscal Year	$ 0
Domestic Plan [Member] | Equity Securities Domestic [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
Percentage of Plan Assets	11.00%	8.00%
Domestic Plan [Member] | Equity Securities Foreign [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5.00%
Percentage of Plan Assets	5.00%	6.00%
Domestic Plan [Member] | Short Term Debt Securities [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%
Percentage of Plan Assets	10.00%	4.00%
Domestic Plan [Member] | Intermediate Debt Securities [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	32.00%
Percentage of Plan Assets	32.00%	32.00%
Domestic Plan [Member] | Long Term Debt Securities [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	41.00%
Percentage of Plan Assets	40.00%	48.00%
Domestic Plan [Member] | Other Investment [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%
Percentage of Plan Assets	2.00%	2.00%
Domestic Plan [Member] | U.S. equity group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 118.8	$ 91.5
Domestic Plan [Member] | Non-U.S. equity group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	56.8	62.6
Domestic Plan [Member] | Corporate and government bond group trust funds - intermediate-term
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	353.6
Domestic Plan [Member] | Corporate and government bond group trust funds long-term [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	443.4
Domestic Plan [Member] | Corporate Bond Group Trust Funds Intermediate Term [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value		342.6
Domestic Plan [Member] | Corporate bond group trust funds - long-term
Pension plans and other postretirement benefit plans
Assets Measured at Fair value		521.5
Domestic Plan [Member] | Other fixed income group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	25.3	22.4
Domestic Plan [Member] | Common/collective trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	92.9	27.4
Domestic Plan [Member] | Annuity and immediate participation contracts
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	19	18.4
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2)
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	1,109.8	1,086.4
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | U.S. equity group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	118.8	91.5
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Non-U.S. equity group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	56.8	62.6
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Corporate and government bond group trust funds - intermediate-term
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	353.6
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Corporate and government bond group trust funds long-term [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	443.4
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Corporate Bond Group Trust Funds Intermediate Term [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value		342.6
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Corporate bond group trust funds - long-term
Pension plans and other postretirement benefit plans
Assets Measured at Fair value		521.5
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Other fixed income group trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	25.3	22.4
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Common/collective trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	92.9	27.4
Domestic Plan [Member] | Significant Other Observable Inputs (Level 2) | Annuity and immediate participation contracts
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	19	18.4
Foreign Plan [Member]
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 21.5	$ 18.2	$ 18.7
Percentage of foreign plan assets to global pension assets	2.00%	2.00%
Expected return on plan assets	4.69%	5.08%
Plan contributions and funding
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 9
Foreign Plan [Member] | Common/collective trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	20.7	$ 17.6
Foreign Plan [Member] | Corporate bonds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.4	0.3
Foreign Plan [Member] | Insurance contracts and other investments
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.4	0.3
Foreign Plan [Member] | Significant Other Observable Inputs (Level 2)
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	21.5	18.2
Foreign Plan [Member] | Significant Other Observable Inputs (Level 2) | Common/collective trust funds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	20.7	17.6
Foreign Plan [Member] | Significant Other Observable Inputs (Level 2) | Corporate bonds
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	0.4	0.3
Foreign Plan [Member] | Significant Other Observable Inputs (Level 2) | Insurance contracts and other investments
Pension plans and other postretirement benefit plans
Assets Measured at Fair value	$ 0.4	$ 0.3
Foreign Plan [Member] | Canada
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	97.00%	97.00%
Expected return on plan assets	4.75%
Foreign Plan [Member] | Canada | Equity securities
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	28.00%
Percentage of Plan Assets	28.00%	28.00%
Foreign Plan [Member] | Canada | Bonds
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	58.00%
Percentage of Plan Assets	58.00%	57.00%
Foreign Plan [Member] | Canada | Other Investments [Member]
Pension plans and other postretirement benefit plans
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	14.00%
Percentage of Plan Assets	14.00%	15.00%
Foreign Plan [Member] | Other country
Pension plans and other postretirement benefit plans
Defined Benefit Plan Percentage of Certain Specified foreign Plan Assets to Total Foreign Plan Assets		3.00%

Other Balance Sheet Accounts (D

Other Balance Sheet Accounts (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Other Current Liabilities
Accrued compensation	$ 60.7	$ 49.6
Environmental contingencies	23.5	32.5
Deferred Revenue, Current	19.5	27.2
Accrued interest	16.5	16.2
Pension liabilities included in other current liabilities	15	14.4
Income taxes payable	12.2	5.7
Other accrued liabilities	70.4	63.3
Other Liabilities, Current	217.8	208.9
Other Liabilities, Noncurrent [Abstract]
Environmental contingencies	46.8	33.8
Noncurrent liability	32.7	27
Fair value of currency and interest rate contracts	22.7	3.2
Deferred revenue	14.9	2.3
Asset Retirement Obligation	10.4	10.2
Deferred income taxes	8.2	2.8
Postemployment liability	5.2	7.2
Other noncurrent liabilities	28.4	40.2
Other Liabilities, Noncurrent	$ 169.3	$ 126.7

Commitments and Contingent Li70

Commitments and Contingent Liabilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)paymentshares	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Feb. 03, 2017USD ($)	Feb. 03, 2014USD ($)
Environmental remediation
ZAI PD Account Funding					$ 34.4
ZAI P D Account, Payment on Third Anniversary of Effective Date of Joint Plan				$ 30
Deferred payment obligations	$ 0	$ 30
ZAI P D Account, Maximum Number of Contingent Deferred Payments | payment	10
ZAI P D Account, Deferred Payments, Each Year for Twenty Years	$ 8
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
Frequency of PD Trust Payments	6 months
Estimated annual expenses related to PD Trust	$ 0.2
Number of Shares Issuable under Warrant | shares	77,372,257
Estimated liability for environmental investigative and remediation costs	$ 70.3	66.3
Pre-tax charges for environmental matters	$ 24.4	28.7	$ 6.4
Site Contingency, Time Frame of Disbursements	2 years
Vermiculite and non vermiculite matters [Member]
Environmental remediation
Pre-tax charges for environmental matters	$ 24.4	29.2	6.4
Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs	25.8	31.2
Pre-tax charges for environmental matters	9.5	24.8	$ 6
Non Vermiculite Related Matters [Member]
Environmental remediation
Estimated liability for environmental investigative and remediation costs	44.5	$ 35.1
Pre-tax charges for environmental matters	14.9
Accrual for Environmental Loss Contingencies, Revision in Estimates	5.9
Accrual for Environmental Loss Contingencies, Charges to Expense for New Losses	$ 7.2
Environmental Exit Costs, Nature of Costs	P10Y

Commitments and Contingent Li71

Commitments and Contingent Liabilities (Details 2) $ in Millions	Dec. 31, 2017USD ($)
Financial Guarantee
Financial assurances
Gross financial assurances issued and outstanding	$ 124.6
Surety Bonds
Financial assurances
Gross financial assurances issued and outstanding	39.5
Standby Letters of Credit
Financial assurances
Gross financial assurances issued and outstanding	85.1
Performance Guarantee [Member]
Financial assurances
Guarantor Obligations, Issued but Not Released to Beneficiary	$ 28.3

Restructuring Expenses and Re72

Restructuring Expenses and Related Asset Impairments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring expenses and related asset impairments
Restructuring expenses	$ 11.5	$ 24.3	$ 11.3
Grace Catalysts Technologies
Restructuring expenses and related asset impairments
Restructuring expenses	3.7	3.4	4.8
Grace Materials Technologies
Restructuring expenses and related asset impairments
Restructuring expenses	(0.1)	15.1	0.8
Corporate, Non-Segment [Member]
Restructuring expenses and related asset impairments
Restructuring expenses	$ 7.9	$ 5.8	$ 5.7

Restructuring Expenses and Re73

Restructuring Expenses and Related Asset Impairments Restructuring Expenses - Liability Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Reserve [Roll Forward]
Restructuring Reserve	$ 6.7	$ 9.6	$ 7.6	$ 2.1
Accruals for severance and other costs	11.4	17.8	11.3
Payments	14.4	16	5.6
Currency translation adjustments and other	$ 0.1	$ 0.2	$ (0.2)

Restructuring Expenses and Re74

Restructuring Expenses and Related Asset Impairments Repositioning Expenses - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Repositioning expenses	$ 15.2	$ 14.3	$ 9.1

Other Expense, net (Details)

Other Expense, net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Income and Expenses [Abstract]
Gain on Business Interruption Insurance Recovery	$ 26.6	$ 0	$ 0
Accounts receivable reserve—Venezuela	10	0	0
Currency transaction effects	5	(1)	(1.5)
Third-party acquisition-related costs	2.9	2.5	0
Net (gain) loss on sales of investments and disposals of assets	(1.6)	1.4	10.6
Chapter 11 expenses, net	1.4	3.4	5.1
Loss on early extinguishment of debt	0	11.1	0
Other miscellaneous expense (income)	2.7	1.3	6.8
Total other (income) expense, net	(8.4)	$ 13.3	$ (13.8)
Business interruption insurance recoveries	25
Business Interruption Insurance Policy Limit	$ 25

Other Comprehensive Income (L76

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		$ (22.2)		$ (2.2)	$ (42.8)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		4.3		(0.1)	0.2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(26.5)		(2.1)	(43)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	[1]	16.9
Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		(2.3)		(2.4)	(3.1)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		(0.8)		(0.9)	(1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(1.5)		(1.5)	(2.1)
Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		0.4		0.5	0.7
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		0.1		0.2	0.2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0.3		0.3	0.5
Net Prior Service Credit arising during period [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent				1.4	5.7
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent				0.5	1.9
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent				0.9	3.8
Net Deferred Actuarial Gain Arising During Period [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		(0.1)			(0.4)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		0			(0.1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(0.1)			(0.3)
Gain on Termination of Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent					(4.5)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent					(1.6)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent					(2.9)
Gain on Curtailment of Postretirement Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent				(0.5)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent				(0.2)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent				(0.3)
Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		(2)		(1)	(1.6)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		(0.7)		(0.4)	(0.6)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(1.3)		(0.6)	(1)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		(23.1)		(1.8)	(43.3)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		2.9	[1]	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(26)		(1.8)	(43.3)
Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent		2.9		0.6	2.1
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		2.1		0.3	0.8
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		$ 0.8		$ 0.3	$ 1.3
[1]	(1)In the 2017 third quarter, Grace recorded an out-of-period adjustment to recognize the accumulated deferred tax liability for its euro loan net investment hedge (see Note 6). The correction resulted in a reduction in deferred tax assets and a charge to "other comprehensive income (loss)" of $16.9 million. Grace has assessed the impact of this error and concluded that it was not material to any prior-period and the impact of correcting the error in 2017 is not material.

Other Comprehensive Income (L77

Other Comprehensive Income (Loss) (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 263.3	$ 372.4	$ 212.5	$ 369
Other comprehensive income (loss)	(26.5)	0.5	(42.8)
Defined Benefit Pension and Other Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	0.9	2.2	3	4
Other comprehensive income (loss) before reclassifications	(0.1)	0.9	3.5
Amounts reclassified from accumulated other comprehensive income (loss)	(1.2)	(1.5)	(4.5)
Other comprehensive income (loss)	(1.3)	(0.6)	(1)
Distribution of GCP		(0.2)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	41.6	67.6	(66.1)	(22.8)
Other comprehensive income (loss) before reclassifications	(26)	(1.8)	(43.3)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Other comprehensive income (loss)	(26)	(1.8)	(43.3)
Distribution of GCP		135.5
Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(2.6)	(3.4)	(3.7)	(5)
Other comprehensive income (loss) before reclassifications	(2.7)	(1.8)	0.6
Amounts reclassified from accumulated other comprehensive income (loss)	3.5	2.1	0.7
Other comprehensive income (loss)	0.8	0.3	1.3
Distribution of GCP		0
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	39.9	66.4	(66.8)	$ (23.8)
Other comprehensive income (loss) before reclassifications	(28.8)	(2.7)	(39.2)
Amounts reclassified from accumulated other comprehensive income (loss)	2.3	0.6	(3.8)
Other comprehensive income (loss)	$ (26.5)	(2.1)	$ (43)
Distribution of GCP		$ 135.3

Shareholders' Equity (Deficit78

Shareholders' Equity (Deficit) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	2,219,234
Stock options exercised	386,300	745,938	728,408
Proceeds from exercise of stock options	$ 16.4	$ 17	$ 26.9
Common stock activity roll forward
Common stock outstanding at the beginning of the period (in shares)	68,309,431	70,533,515	72,922,565
Stock options exercised	386,300	745,938	728,408
Shares issued	49,897	110,953	9,378
Shares forfeited	(29,783)	(305,678)	(3,120)
Shares repurchased	(935,435)	(2,775,297)	(3,123,716)
Common stock outstanding at the end of the period (in shares)	67,780,410	68,309,431	70,533,515
Shares issued to Board of Directors [Member]
Common stock activity roll forward
Shares issued	10,507
Net share settlement [Member]
Common stock activity roll forward
Shares issued	8,215
2014 [Member] | Deferred Compensation, Share-based Payments [Member]
Common stock activity roll forward
Shares issued	24,432
2016 [Member]
Common stock activity roll forward
Shares issued	6,743

Stock Incentive Plans (Details)

Stock Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock incentive plan
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, Plan Modification, Incremental Compensation Cost		$ 0.6
Stock Option Activity Roll Forward, Number of Shares
Options exercised (in shares)	(386,300)	(745,938)	(728,408)
Employee nonstatutory stock options
Stock Option Activity Roll Forward, Number of Shares
Options outstanding at the beginning of the period (in shares)	1,940,785	2,320,687	2,523,790
Options exercised (in shares)	(386,300)	(745,938)	(728,408)
Options forfeited (in shares)	(34,545)	(9,458)	(25,000)
Options terminated (in shares)	(23,320)	(2,426)	(500)
Options granted (in shares)	316,830	377,920	550,805
Options outstanding at the end of the period (in shares)	1,813,450	1,940,785	2,320,687
Stock Option Activity Roll Forward, Average Exercise Price
Average exercise price at the beginning of the period (in dollars per share)	$ 66.83	$ 71.01	$ 55.77
Options exercised (in dollars per share)	45.21	36.97	36.85
Options forfeited (in dollars per share)	72.97	73.40	92.57
Options terminated (in dollars per share)	75.60	67.06	100.29
Options granted (in dollars per share)	71.37	68.32	77.31
Average exercise price at the end of the period (in dollars per share)		66.83	71.01
Stock Option Activity, Additional Disclosures
Granted (in dollars per share)	$ 13	$ 12.90	$ 19.28
Stock Option Activity Roll Forward, Non-vested, Number of Shares
Nonvested options outstanding at the beginning of the period (in shares)	719,027	878,031
Options granted (in shares)	316,830	377,920	550,805
Vested/exercised (in shares)	(417,969)
Forfeited (in shares)	(57,865)
Stock Option Activity Roll Forward, Non-vested, Weighted-Average Grant Date Fair Value
Weighted Average Grant Date Fair Value for nonvested options (in dollars per share)	$ 17.76
Granted (in dollars per share)	13	$ 12.90	$ 19.28
Vested/Exercised (in dollars per share)	18.78
Forfeited (in dollars per share)	$ 18.09
Summary of intrinsic value
Intrinsic value for the options outstanding	$ 2.8
Intrinsic value for the options exercisable	2.3
Total intrinsic value of all options exercised	$ 10.3	$ 25.9	$ 46.1
Minimum
Stock incentive plan
Stock incentive plan vesting period	1 year
Maximum
Stock incentive plan
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Options Granted
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 7.4	$ 11.2	$ 3.3
Options, additional information
Total unrecognized stock-based compensation expense	$ 2.9
Weighted-average period over which this expense will be recognized	10 months 25 days
Minimum
Options, additional information
Performance Based Compensation Payout Target	0.00%
Maximum
Options, additional information
Performance Based Compensation Payout Target	200.00%
Employee nonstatutory stock options
Stock Incentive Plans
Number Outstanding (in shares)	1,813,450
Number Exercisable (in shares)	1,094,423
Weighted-average remaining contractual term of exercisable options (in years)	2 years 3 months 22 days
Options Granted
Options granted (in shares)	316,830	377,920	550,805
Stock or Unit Option Plan Expense	$ 4.3	$ 6	$ 9.9
Assumptions used for estimating the fair value of stock options
Weighted average expected volatility (as a percent)	24.90%	26.60%	24.50%
Risk-free rate	1.66%	1.01%	1.30%
Dividend yield	1.20%	1.00%	0.00%
Volatility rate, minimum	24.70%	26.20%	23.00%
Volatility rate, maximum	25.10%	27.50%	27.20%
Options, additional information
Stock or Unit Option Plan Expense	$ 4.3	$ 6	$ 9.9
Employee nonstatutory stock options | Minimum
Assumptions used for estimating the fair value of stock options
Expected term	3 years	3 years	3 years
Employee nonstatutory stock options | Maximum
Assumptions used for estimating the fair value of stock options
Expected term	4 years	4 years	4 years
Employee nonstatutory stock options | Exercise Price Range One [Member]
Stock Incentive Plans
Exercise price, low	$ 0
Exercise price, high	10
Employee nonstatutory stock options | Exercise Price Range Two [Member]
Stock Incentive Plans
Exercise price, low	10
Exercise price, high	20
Employee nonstatutory stock options | Exercise Price Range Three [Member]
Stock Incentive Plans
Exercise price, low	20
Exercise price, high	30
Employee nonstatutory stock options | Exercise Price Range Four [Member]
Stock Incentive Plans
Exercise price, low	30
Exercise price, high	40
Employee nonstatutory stock options | Exercise Price Range Five [Member]
Stock Incentive Plans
Exercise price, low	40
Exercise price, high	50
Employee nonstatutory stock options | Exercise Price Range Six [Member]
Stock Incentive Plans
Exercise price, low	50
Exercise price, high	60
Employee nonstatutory stock options | Exercise Price Range Seven [Member]
Stock Incentive Plans
Exercise price, low	60
Exercise price, high	$ 70
Number Outstanding (in shares)	586,054
Number Exercisable (in shares)	350,469
Outstanding Weighted- Average Remaining Contractual Life (Years)	2 years 7 days
Weighted-Average Exercise Price (in dollars per share)	$ 63.90
Employee nonstatutory stock options | Exercise Price Range Eight [Member]
Stock Incentive Plans
Exercise price, low	70
Exercise price, high	$ 80
Number Outstanding (in shares)	1,200,806
Number Exercisable (in shares)	724,000
Outstanding Weighted- Average Remaining Contractual Life (Years)	2 years 5 months 23 days
Weighted-Average Exercise Price (in dollars per share)	$ 75.97
Employee nonstatutory stock options | Exercise Price Range Nine [Member]
Stock Incentive Plans
Exercise price, low	80
Exercise price, high	$ 90
Number Outstanding (in shares)	26,590
Number Exercisable (in shares)	19,954
Outstanding Weighted- Average Remaining Contractual Life (Years)	1 year 1 month 27 days
Weighted-Average Exercise Price (in dollars per share)	$ 80.76
Employee nonstatutory stock options | Exercise Price Range Ten [Member]
Stock Incentive Plans
Exercise price, low	90
Exercise price, high	100
Employee nonstatutory stock options | Exercise Price Range Eleven [Member]
Stock Incentive Plans
Exercise price, low	100
Exercise price, high	$ 110
Restricted Stock Units (RSUs) [Member]
Options, additional information
Performance Based Units Granted	57,600	77,358	123,846
Granted (in dollars per share)		$ 68.90	$ 67.95
Performance Based Units [Member]
Options, additional information
Performance Based Units Granted	115,158	124,952	1,864
Granted (in dollars per share)		$ 68.50
Percent of Units Expected to Settle in Common Stock			53.00%
Percent of Units Expected to Settle in Cash			47.00%
Restricted Stock Units (RSUs) and Performance Stock Units (PSUs) [Member]
Options Granted
Stock or Unit Option Plan Expense	$ 10.3	$ 8.6	$ 5.8
Options, additional information
Performance Based Units, Forfeitures	16,395	15,197	10,641
Granted (in dollars per share)	$ 71.37
Percent of Units Expected to Settle in Common Stock	65.00%	67.00%
Percent of Units Expected to Settle in Cash	35.00%	33.00%
Stock or Unit Option Plan Expense	$ 10.3	$ 8.6	$ 5.8
Stock or Unit Option Plan Expense, Unrecognized	$ 14.1
Weighted-Average Remaining Contractual Term (in years)	1 year 3 months 19 days

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016	[2]	Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 08, 2017	Feb. 05, 2015	Feb. 04, 2014
Numerators
Income (loss) from continuing operations attributable to W. R. Grace & Co. shareholders																	$ 11.2	$ 107	$ 124
Income (loss) from discontinued operations, net of income taxes																	0	(12.9)	20.2
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ (123)	[1]	$ 47.4		$ 43.9		$ 42.9		$ 15.3		$ 39.6		$ 38.7		$ 0.5		$ 11.2	$ 94.1	$ 144.2
Denominators
Weighted average common shares-basic calculation																	68,100,000	70,100,000	72,000,000
Dilutive effect of employee stock options (in shares)																	100,000	400,000	600,000
Weighted average common shares-diluted calculation																	68,200,000	70,500,000	72,600,000
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations																	$ 0.16	$ 1.53	$ 1.72
Income (loss) from discontinued operations, net of income taxes																	0	(0.19)	0.28
Net income (loss)	$ (1.81)	[1],[3]	$ 0.70	[3]	$ 0.64	[3]	$ 0.63	[3]	$ 0.22	[4]	$ 0.56	[4]	$ 0.55	[4]	$ 0.01	[4]	0.16	1.34	2
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Income (loss) from continuing operations																	0.16	1.52	1.71
Income (loss) from discontinued operations, net of income taxes																	0	(0.19)	0.28
Net income (loss)	$ (1.81)	[1],[3]	$ 0.70	[3]	$ 0.64	[3]	$ 0.63	[3]	$ 0.22	[4]	$ 0.56	[4]	$ 0.55	[4]	$ 0.01	[4]	$ 0.16	$ 1.33	$ 1.99
Stock options excluded from computation of diluted earnings per share (in shares)																	1,500,000	1,300,000	400,000
Share Repurchase Program [Line Items]
Stock Repurchase Program, Authorized Amount																				$ 250	$ 500	$ 500
Shares repurchased																	935,435	2,775,297	3,123,716
Payments for Repurchase of Common Stock																	$ 65	$ 195.1	$ 301.5
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 218.9																$ 218.9
Minimum
Share Repurchase Program [Line Items]
Stock Repurchase Program, Period in Force																	24 months
Maximum
Share Repurchase Program [Line Items]
Stock Repurchase Program, Period in Force																	36 months
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.
[3]	(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.
[4]	(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.

Operating Segment Information82

Operating Segment Information (Details) $ in Millions	3 Months Ended										12 Months Ended
	Dec. 31, 2017USD ($)		Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)		Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Operating segment information
Number of Reportable Segments | segment											2
Net Sales
Net sales	$ 459.5	[1]	$ 429.5	$ 429.5	$ 398	$ 440.8	[2]	$ 404.5	$ 390.5	$ 362.8	$ 1,716.5	$ 1,598.6	$ 1,628.2
Adjusted EBIT
Gain on termination of postretirement plans related to current businesses											0	0.2	1.9
Certain Pension Costs											13	12.3	20.4
Adjusted EBIT											414	400.3	345.8
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization											111.5	100.3	99.2
Payments to Acquire Productive Assets [Abstract]
Capital Expenditures											125.2	116.9	118.8
Assets
Total Assets	2,907					2,911.8					2,907	2,911.8	3,645.7
Disposal Group, Including Discontinued Operation, Assets	0					0					0	0	870.5
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract]
Adjusted EBIT											414	400.3	345.8
Pension MTM adjustment and other related costs, net											(51.1)	(60.3)	(30.5)
Costs related to legacy product, environmental and other claims											30.8	35.4	6.1
Restructuring and repositioning expenses											26.7	38.6	20.4
Accounts receivable reserve-Venezuela											(10)	0	0
Third-party acquisition-related costs											2.9	2.5	0
Income and expense items related to divested businesses											(2.3)	0.1	1.5
Gain (loss) on sale of product line											0	1.7	0
Gain on termination and curtailment of postretirement plans related to divested businesses											0	0.3	2.6
Amortization of Acquired Inventory Fair Value Adjustment											0	8	0
Loss on early extinguishment of debt											0	(11.1)	0
Interest expense, net											(78.5)	(80.5)	(99.1)
Net income (loss) attributable to noncontrolling interests											(0.8)	0	(0.1)
Income (loss) from continuing operations before income taxes											$ 210.9	166	193.7
Catalysts Technologies
Operating segment information
Number of operating segments | segment											2
Net Sales
Net sales											$ 1,276.5	1,163.7	1,162.1
Adjusted EBIT
Operating income (loss)											395.4	367.8	347.3
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization											87.1	77.4	68.1
Payments to Acquire Productive Assets [Abstract]
Capital Expenditures											100.9	84.9	66.3
Materials Technologies
Net Sales
Net sales											440	434.9	466.1
Adjusted EBIT
Operating income (loss)											100.6	104	96.9
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization											19.6	19.5	23.2
Payments to Acquire Productive Assets [Abstract]
Capital Expenditures											20.9	24	24.6
Corporate, Non-Segment [Member]
Adjusted EBIT
Operating income (loss)											(69)	(59.4)	(79.9)
Depreciation, Depletion and Amortization [Abstract]
Depreciation and amortization											4.8	3.4	7.9
Payments to Acquire Productive Assets [Abstract]
Capital Expenditures											3.4	8	27.9
Operating Segments [Member] | Catalysts Technologies
Assets
Total Assets	1,757.1					1,675.1					1,757.1	1,675.1	1,390.8
Operating Segments [Member] | Materials Technologies
Assets
Total Assets	326.8					313.1					326.8	313.1	333.4
Corporate, Non-Segment [Member]
Assets
Total Assets	$ 823.1					$ 923.6					$ 823.1	$ 923.6	$ 1,051
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.

Operating Segment Information83

Operating Segment Information (Details 2) - USD ($) $ in Millions		3 Months Ended										12 Months Ended
		Dec. 31, 2017		Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Geographic Area Data
Assets		$ 2,907					$ 2,911.8					$ 2,907	$ 2,911.8	$ 3,645.7
Net sales		459.5	[1]	$ 429.5	$ 429.5	$ 398	440.8	[2]	$ 404.5	$ 390.5	$ 362.8	1,716.5	1,598.6	1,628.2
Long-Lived Assets	[3]	831.8					756.6					831.8	756.6	636.8
Total North America
Geographic Area Data
Net sales												486	490.7	490
Long-Lived Assets	[3]	615.3					578.4					615.3	578.4	477.1
United States
Geographic Area Data
Net sales												437.3	446.2	444.7
Long-Lived Assets	[3]	599.8					564.5					599.8	564.5	464.1
Canada
Geographic Area Data
Net sales												48.7	44.5	45.3
Long-Lived Assets	[3]	15.5					13.9					15.5	13.9	13
Europe Middle East Africa
Geographic Area Data
Net sales												667.7	647.8	621.2
Long-Lived Assets	[3]	187.5					149.2					187.5	149.2	128.3
Germany
Geographic Area Data
Long-Lived Assets	[3]	142.2					109.7					142.2	109.7	110.9
EMEA excluding Germany [Member]
Geographic Area Data
Long-Lived Assets	[3]	45.3					39.5					45.3	39.5	17.4
Asia Pacific
Geographic Area Data
Net sales												459.8	348.9	390.9
Long-Lived Assets	[3]	21.1					21.5					21.1	21.5	25.9
Latin America
Geographic Area Data
Net sales												103	111.2	126.1
Long-Lived Assets	[3]	7.9					7.5					7.9	7.5	5.5
Grace Catalysts Technologies
Geographic Area Data
Net sales												1,276.5	1,163.7	1,162.1
Grace Materials Technologies
Geographic Area Data
Net sales												440	434.9	466.1
Operating Segments [Member] | Grace Catalysts Technologies
Geographic Area Data
Assets		1,757.1					1,675.1					1,757.1	1,675.1	1,390.8
Operating Segments [Member] | Grace Materials Technologies
Geographic Area Data
Assets		326.8					313.1					326.8	313.1	333.4
Corporate, Non-Segment [Member]
Geographic Area Data
Assets		$ 823.1					$ 923.6					$ 823.1	$ 923.6	$ 1,051
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.
[3]	(1)Long-lived assets include properties and equipment and the noncurrent asset related to a planned hydroprocessing catalyst plant to be transferred to ART upon completion. (See Note 18.)

Operating Segment Information O

Operating Segment Information Operating Segment Information (Details 3) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	[2]	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales	$ 459.5		$ 429.5	$ 429.5	$ 398	$ 440.8		$ 404.5	$ 390.5	$ 362.8	$ 1,716.5	$ 1,598.6	$ 1,628.2
Grace Catalysts Technologies
Segment Reporting Information [Line Items]
Net sales											1,276.5	1,163.7	1,162.1
Materials Technologies
Segment Reporting Information [Line Items]
Net sales											440	434.9	466.1
Refining Catalysts [Member] | Grace Catalysts Technologies
Segment Reporting Information [Line Items]
Net sales											758.1	724.9	764.5
Polyolefin and Chemical Catalysts [Member] | Grace Catalysts Technologies
Segment Reporting Information [Line Items]
Net sales											518.4	438.8	397.6
Coatings [Member] | Materials Technologies
Segment Reporting Information [Line Items]
Net sales											142.2	136.5	133.6
Consumer/Pharma [Member] | Materials Technologies
Segment Reporting Information [Line Items]
Net sales											123.3	121.9	125.1
Chemical process [Member] | Materials Technologies
Segment Reporting Information [Line Items]
Net sales											153.5	142.6	137
Other materials [Member] | Materials Technologies
Segment Reporting Information [Line Items]
Net sales											$ 21	$ 33.9	$ 70.4
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.

Unconsolidated Affiliates (Deta

Unconsolidated Affiliates (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment, ownership interest	50.00%
Investment in unconsolidated affiliate	$ 125,900,000	$ 117,600,000
Equity in earnings of unconsolidated affiliates	25,900,000	29,800,000	$ 20,400,000
ART's assets, liabilities and results of operations:
Current assets	239,800,000	249,200,000
Noncurrent assets	91,500,000	84,800,000
Total assets	331,300,000	334,000,000
Current liabilities	82,400,000	102,000,000
Noncurrent liabilities	300,000	300,000
Total liabilities	82,700,000	102,300,000
Net sales	447,300,000	388,900,000	415,300,000
Costs and expenses applicable to net sales	379,800,000	322,100,000	366,600,000
Income before income taxes	53,600,000	60,800,000	42,800,000
Net income	52,100,000	59,300,000	41,100,000
Related party transactions:
Product manufactured for ART	213,800,000	210,400,000	258,900,000
Related Party Transaction, markup of product manufactured for ART reducing COGS	4,200,000	4,200,000	5,100,000
Charges for fixed costs, research and development and selling, general and administrative services to ART	41,700,000	33,800,000	$ 31,600,000
Schedule of Investments [Line Items]
Accounts receivable	20,100,000	14,900,000
Noncurrent asset	32,700,000	27,000,000
Accounts payable	22,300,000	28,700,000
Debt payable within one year	8,600,000	7,600,000
Debt payable after one year	33,800,000	31,900,000
Noncurrent liability	32,700,000	27,000,000
Chevron
Schedule of Investments [Line Items]
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000
Commitment fee on credit facility	0.10%
W R Grace & Co. [Member]
Schedule of Investments [Line Items]
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000
Commitment fee on credit facility	0.10%
Long-term Line of Credit	$ 0	$ 0

Quarterly Summary and Statist86

Quarterly Summary and Statistical Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017		Mar. 31, 2017		Dec. 31, 2016		Sep. 30, 2016		Jun. 30, 2016		Mar. 31, 2016		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 459.5	[1]	$ 429.5		$ 429.5		$ 398		$ 440.8	[2]	$ 404.5		$ 390.5		$ 362.8		$ 1,716.5	$ 1,598.6	$ 1,628.2
Gross Profit	167.5	[1]	173.3		169.3		153.2		161.8	[2]	168.2		173.2		152.7		663.3	655.9	651.7
Net income (loss)	(123.1)	[1]	47.1		43.5		42.9		15.6	[2]	39.7		38.5		0.3		10.4	94.1	144.1
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ (123)	[1]	$ 47.4		$ 43.9		$ 42.9		$ 15.3	[2]	$ 39.6		$ 38.7		$ 0.5		$ 11.2	$ 94.1	$ 144.2
Basic earnings per share:
Net income (loss) (in dollars per share)	$ (1.81)	[1],[3]	$ 0.70	[3]	$ 0.64	[3]	$ 0.63	[3]	$ 0.22	[2],[4]	$ 0.56	[4]	$ 0.55	[4]	$ 0.01	[4]	$ 0.16	$ 1.34	$ 2
Diluted earnings per share:
Net income (loss) (in dollars per share)	(1.81)	[1],[3]	0.70	[3]	0.64	[3]	0.63	[3]	0.22	[2],[4]	0.56	[4]	0.55	[4]	0.01	[4]	0.16	1.33	1.99
Dividends per common share	0.21		0.21		0.21		0.21		0.17		0.17		0.17		0		$ 0.84	$ 0.51	$ 0
Market price of common stock:
High (in dollars per share)	77.37	[5]	73.77	[5]	72.72	[5]	74.63	[5]	74.38	[6],[7]	80.56	[6],[7]	80.39	[6],[7]	98.15	[6],[7],[8]
Low (in dollars per share)	69.37	[5]	65.84	[5]	67.12	[5]	67.54	[5]	63.37	[6],[7]	71.47	[6],[7]	70.59	[6],[7]	63.84	[6],[7]
Close (in dollars per share)	$ 70.13	[5]	$ 72.15	[5]	$ 72.01	[5]	$ 69.71	[5]	$ 67.64	[6],[7]	$ 73.80	[6],[7]	$ 73.21	[6],[7]	$ 71.18	[6],[7]
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.
[3]	(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.
[4]	(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.
[5]	(2)Principal market: New York Stock Exchange.
[6]	(2)Principal market: New York Stock Exchange.
[7]	(3)Share prices subsequent to February 3, 2016, reflect the Separation and exclude separate trading of GCP common stock.
[8]	(4)Price is a pre-Separation market price of common stock

SCHEDULE II-VALUATION AND QUA87

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Valuation and qualifying accounts deducted from assets and Reserves:
Accounts receivable reserve—Venezuela		$ 10		$ 0		$ 0
Change in valuation allowance		(19.4)		23		(2.3)
Allowances for notes and accounts receivable
Reconciliation of valuation and reserves roll forward
Balance at beginning of period		2.8	[1]	1.4		1
Additions charged to costs and expenses		10.6	[1]	2.4		0.5
Deductions		(1.3)	[1]	(1.1)		(0.1)
Other net	[2]	(0.1)	[1]	0.1		0
Balance at end of period		12	[1]	2.8	[1]	1.4
Valuation allowance for deferred tax assets
Reconciliation of valuation and reserves roll forward
Balance at beginning of period		31.4	[3],[4]	8.4	[4],[5]	10.7	[5]
Additions charged to costs and expenses		0.3	[3]	11.6	[4]	0.4	[5]
Deductions		(19.7)	[3]	(9.1)	[4]	(2.6)	[5]
Other net	[2]	0	[3]	20.5	[4]	(0.1)	[5]
Balance at end of period		12	[3]	31.4	[3],[4]	8.4	[4],[5]
Reserves for environmental remediation
Reconciliation of valuation and reserves roll forward
Balance at beginning of period		66.3		55.2		61.1
Additions charged to costs and expenses		24.4		29.2		6.4
Deductions		(20.4)		(18.1)		(12.3)
Other net	[2]	0		0		0
Balance at end of period		70.3		66.3		55.2
Reserves for retained obligations of divested businesses
Reconciliation of valuation and reserves roll forward
Balance at beginning of period		11.7		13.5		13.5
Additions charged to costs and expenses		1.5		0		0
Deductions		(0.4)		(1.8)		0
Other net	[2]	0		0		0
Balance at end of period		$ 12.8		$ 11.7		$ 13.5
[1]	(2)The allowance for accounts receivable increased primarily due to a $10.0 million charge to fully reserve for a trade receivable from a Venezuela-based customer related to increased economic uncertainty and the recent political unrest and sanctions.
[2]	(1)Effects of currency translation and the Separation
[3]	(3)The valuation allowance decreased $19.4 million from December 31, 2016, to December 31, 2017. The decrease was primarily due to the effects of U.S. tax reform.
[4]	(4)The valuation allowance increased $23.0 million from December 31, 2015, to December 31, 2016. The increase was primarily due to the adoption of ASU 2016-09 as well as the ability to utilize NOL carryforwards as a result of the Separation.
[5]	(5)The valuation allowance decreased $2.3 million from December 31, 2014, to December 31, 2015. The decrease was primarily due to a reduction in the valuation allowance on state NOL carryforwards.

Acquisition (Details)

Acquisition (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2015
Business Acquisition [Line Items]
Net assets acquired	$ 250.6
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	3.3
Business Acquisition, Goodwill, Expected Tax Deductible Amount	43
Inventories	30.2
Properties and equipment	95
Goodwill	394.2	$ 402.4	$ 336.5
Intangible assets	$ 61.6
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Customer Lists [Member]
Business Acquisition [Line Items]
Intangible assets	$ 39.9
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Trademarks [Member]
Business Acquisition [Line Items]
Intangible assets	$ 13.4
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Technology-Based Intangible Assets [Member]
Business Acquisition [Line Items]
Intangible assets	$ 8.3
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Polyolefin Catalysts [Member]
Business Acquisition [Line Items]
Goodwill	$ 63.8
Subsequent Event [Member]
Business Acquisition [Line Items]
Net assets acquired		$ 416

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended										12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	[2]	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Feb. 29, 2016	Jan. 31, 2016
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Net sales	$ 459.5		$ 429.5	$ 429.5	$ 398	$ 440.8		$ 404.5	$ 390.5	$ 362.8	$ 1,716.5	$ 1,598.6	$ 1,628.2
Cost of goods sold											1,053.2	942.7	976.5
Gross Profit	$ 167.5		$ 173.3	$ 169.3	$ 153.2	$ 161.8		$ 168.2	$ 173.2	152.7	663.3	655.9	651.7
Selling, general and administrative expenses											302.6	308.8	318.9
Research and development expenses											53.5	48.8	47.1
Repositioning expenses											15.2	14.3	9.1
Interest expense and related financing costs											79.5	81.5	99.4
Other expense, net											(8.4)	13.3	(13.8)
Total costs and expenses											452.4	489.9	458
Income (loss) from discontinued operations, net of income taxes											0	(12.9)	20.2
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Distribution from GCP											$ 0	750	0
Grace Construction Products [Member] | Discontinued Operations, Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Net sales												99.6	1,423.3
Cost of goods sold												62.6	907.5
Gross Profit												37	515.8
Selling, general and administrative expenses												21.6	251.2
Research and development expenses												1.7	22.5
Loss in Venezuela												0	59.6
Repositioning expenses												22	55.1
Interest expense and related financing costs												0.7	1.5
Other expense, net												3.9	9.9
Total costs and expenses												49.9	399.8
(Loss) Income from discontinued operations before income taxes												(12.9)	116
Benefit from (provision for) income taxes												0.1	(95)
(Loss) Income from discontinued operations after income taxes												(12.8)	21
Less: Net income attributable to noncontrolling interests												(0.1)	(0.8)
Income (loss) from discontinued operations, net of income taxes												$ (12.9)	$ 20.2
GCP Applied Technologies [Member] | Nine Point Five Percent Senior Notes Due 2023 [Member] | Senior Notes [Member] | Grace Construction Products [Member] | Discontinued Operations, Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Proceeds from Issuance of Long-term Debt										525
Debt Instrument, Interest Rate, Stated Percentage															9.50%
Distribution from GCP										500
GCP Applied Technologies [Member] | GCP Credit Agreement [Member] | Line of Credit [Member] | Grace Construction Products [Member] | Discontinued Operations, Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Proceeds from Issuance of Long-term Debt										525
Distribution from GCP										$ 250
Notes Payable, Other Payables [Member] | GCP Applied Technologies [Member] | GCP Credit Agreement [Member] | Line of Credit [Member] | Grace Construction Products [Member] | Discontinued Operations, Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity														$ 275
Revolving Credit Facility [Member] | GCP Applied Technologies [Member] | GCP Credit Agreement [Member] | Line of Credit [Member] | Grace Construction Products [Member] | Discontinued Operations, Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Additional Disclosures [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity														$ 250
[1]	(3)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment, as well as adjustments related to the estimated impacts of the U.S. Tax Cuts and Jobs Act of 2017.
[2]	(5)Fourth quarter "gross profit," "net income (loss)," and "net income (loss) attributable to W. R. Grace & Co. shareholders" include the effects of the annual pension mark-to-market adjustment.

Uncategorized Items - gra-20171

Label	Element	Value
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents	us-gaap_DisposalGroupIncludingDiscontinuedOperationCashAndCashEquivalents	$ 143,400,000