W.R. Grace & Co. (GRA) 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document and Entity Information
Trading Symbol	GRA
Entity Registrant Name	W R GRACE & CO.
Entity Address, Address Line One	7500 Grace Drive
Entity Address, City or Town	Columbia
Entity Address, State or Province	Maryland
Entity Address, Postal Zip Code	21044-4098
Entity Central Index Key	0001045309
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		66,914,212
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Local Phone Number	(410) 531-4000

Consolidated Statements of Oper

Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues	$ 469.5	$ 431.5
Cost of goods sold	280.9	262
Gross profit	188.6	169.5
Selling, general and administrative expenses	73.2	68.4
Research and development expenses	17	14.7
Costs related to legacy matters	46.9	2
Equity in earnings of unconsolidated affiliate	(4.1)	(5.4)
Restructuring and repositioning expenses	2.3	5.6
Interest expense and related financing costs	20	19.3
Other (income) expense, net	(2.2)	(3.3)
Total costs and expenses	153.1	101.3
Income (loss) before income taxes	35.5	68.2
(Provision for) benefit from income taxes	(10.9)	(24.8)
Net income (loss)	24.6	43.4
Less: Net (income) loss attributable to noncontrolling interests	0.1	0.2
Net income (loss) attributable to W. R. Grace & Co. shareholders	$ 24.7	$ 43.6
Basic earnings per share:
Net income (loss) (in dollars per share)	$ 0.37	$ 0.64
Weighted average number of basic shares (in shares)	66.8	67.6
Diluted earnings per share:
Net income (loss) (in dollars per shares)	$ 0.37	$ 0.64
Weighted average number of diluted shares (in shares)	66.9	67.7
Dividends per common share (in dollars per shares)	$ 0.27	$ 0.24

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 24.6	$ 43.4
Other comprehensive income (loss), net of income taxes:
Defined benefit pension and other postretirement plans	(0.1)	(0.2)
Currency translation adjustments	11.7	(18.2)
Gain (loss) from hedging activities	(3)	1.8
Total other comprehensive income (loss)	8.6	(16.6)
Comprehensive income (loss)	33.2	26.8
Less: comprehensive (income) loss attributable to noncontrolling interests	0.1	0.2
Comprehensive income (loss) attributable to W. R. Grace & Co. shareholders	$ 33.3	$ 27

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
OPERATING ACTIVITIES
Net income (loss)	$ 24.6	$ 43.4
Reconciliation to net cash provided by (used for) operating activities:
Depreciation and amortization	24.9	25
Equity in earnings of unconsolidated affiliate	(4.1)	(5.4)
Costs related to legacy matters	46.9	2
Cash paid for legacy matters	3.2	6.3
Provision for (benefit from) income taxes	10.9	24.8
Cash paid for income taxes	(10.9)	(8.9)
Income tax refunds received	0.8	0
Interest expense and related financing costs	20	19.3
Cash paid for interest	(6.5)	(5.3)
Defined benefit pension expense	4.8	3.8
Cash paid under defined benefit pension arrangements	(4)	(3.7)
Changes in assets and liabilities, excluding effect of currency translation and acquisitions:
Trade accounts receivable	26.6	20.1
Inventories	(35.5)	(23)
Accounts payable	3.5	10.5
All other items, net	(27.8)	(7.3)
Net cash provided by (used for) operating activities	71	89
INVESTING ACTIVITIES
Capital expenditures	(38.2)	(50.1)
Other investing activities	(7.9)	1.6
Net cash provided by (used for) investing activities	(46.1)	(48.5)
FINANCING ACTIVITIES
Borrowings under credit arrangements	2.2	8.6
Repayments under credit arrangements	(5.7)	(11.7)
Cash paid for repurchases of common stock	(4.8)	(35)
Proceeds from exercise of stock options	9.2	0.8
Dividends paid to shareholders	(18.4)	(16.2)
Other financing activities	(4.3)	(1.6)
Net cash provided by (used for) financing activities	(21.8)	(55.1)
Effect of currency exchange rate changes on cash, cash equivalents, and restricted cash	(0.3)	2.4
Net increase (decrease) in cash and cash equivalents	2.8	(12.2)
Cash, cash equivalents, and restricted cash, beginning of period	201	163.5	$ 163.5
Cash, cash equivalents, and restricted cash, end of period	203.8	151.3	$ 201
Supplemental disclosure of cash flow information
Capital expenditures in accounts payable	$ 44.3	$ 29.6

Consolidated Balance Sheets (un

Consolidated Balance Sheets (unaudited) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 203.4	$ 200.5
Restricted cash and cash equivalents	0.4	0.5
Trade accounts receivable, less allowance of $X.X (2018—$X.X)	257.8	288.5
Inventories	316.2	281.1
Other current assets	202.8	86.7
Total Current Assets	980.6	857.3
Properties and equipment, net of accumulated depreciation and amortization of $X.X (2018—$X.X)	1,043.7	1,011.7
Goodwill	540.3	540.4
Technology and other intangible assets, net	351.1	356.5
Deferred income taxes	525.6	529.4
Investment in unconsolidated affiliate	159.5	156.1
Other assets	45.6	113.9
Total Assets	3,646.4	3,565.3
Current Liabilities
Debt payable within one year	22.5	22.3
Accounts payable	257.5	248.6
Other current liabilities	356	243.5
Total Current Liabilities	636	514.4
Debt payable after one year	1,961.6	1,961
Defined Benefit Pension Plan Liabilities Noncurrent Unfunded	362.9	366
Defined Benefit Pension Plan Liabilities Noncurrent Underfunded	67.6	67.1
Other liabilities	264.5	319.8
Total Liabilities	3,292.6	3,228.3
Commitments and Contingencies—Note 8
Equity
Common stock issued, par value $0.01; 300,000,000 shares authorized; outstanding: XXX (2017—XXX)	0.7	0.7
Paid-in capital	469.1	481.1
Retained earnings	683.3	676.7
Treasury stock, at cost: shares: XXX (2017—XXX)	(881.8)	(895.5)
Accumulated other comprehensive income (loss)	76.5	67.9
Total W. R. Grace & Co. Shareholders’ Equity	347.8	330.9
Noncontrolling interests	6	6.1
Total Equity	353.8	337
Total Liabilities and Equity	$ 3,646.4	$ 3,565.3

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 11.7	$ 11.6
Accumulated depreciation	$ 1,495.1	$ 1,482.8
Common stock issued, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock issued, shares authorized (in shares)	300,000,000	300,000,000
Common stock issued, shares outstanding (in shares)	66,915,399	66,792,968
Treasury stock, at cost (shares)	10,541,234	10,663,659

Consolidated Statements of Equi

Consolidated Statements of Equity (unaudited) - USD ($) $ in Millions	Total	Common Stock and Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity
Adjustment to retained earnings for adoption of ASC 606 | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]	$ 3.2	$ 0	$ 3.2	$ 0	$ 0	$ 0
Beginning balance at Dec. 31, 2017	263.3	475.5	573.1	(832.1)	39.9	6.9
Increase (Decrease) in Stockholders' Equity
Net income	43.4	0	43.6	0	0	(0.2)
Repurchase of common stock	(35)	0	0	(35)	0	0
Payments in consideration of employee tax obligations related to stock-based compensation	(0.7)	(0.7)	0	0	0	0
Stock-based compensation	3.7	3.7	0	0	0	0
Exercise of stock options	0.8	(0.4)	0	1.2	0	0
Shares issued	0	(1.3)	0	1.3	0	0
Dividends declared	(16.2)	0	(16.2)	0	0	0
Other comprehensive (loss) income	(16.6)	0	0	0	(16.6)	0
Ending balance at Mar. 31, 2018	245.9	476.8	603.7	(864.6)	23.3	6.7
Beginning balance at Dec. 31, 2018	337	481.8	676.7	(895.5)	67.9	6.1
Increase (Decrease) in Stockholders' Equity
Net income	24.6	0	24.7	0	0	(0.1)
Repurchase of common stock	(4.8)	0	0	(4.8)	0	0
Payments in consideration of employee tax obligations related to stock-based compensation	(4.3)	(4.3)	0	0	0	0
Stock-based compensation	1.9	1.9	0	0	0	0
Exercise of stock options	9.2	(2.2)	0	11.4	0	0
Shares issued	(0.3)	(7.4)	0	7.1	0	0
Dividends declared	(18.1)	0	(18.1)	0	0	0
Other comprehensive (loss) income	8.6	0	0	0	8.6	0
Ending balance at Mar. 31, 2019	$ 353.8	$ 469.8	$ 683.3	$ (881.8)	$ 76.5	$ 6

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies	3 Months Ended
	Mar. 31, 2019
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 consumer/pharma, chemical process, and coatings 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. Basis of Presentation The interim Consolidated Financial Statements presented herein are unaudited and should be read in conjunction with the Consolidated Financial Statements presented in the Company’s 2018 Annual Report on Form 10-K. Such interim Consolidated Financial Statements reflect all adjustments that, in the opinion of management, are necessary for a fair statement of the results of the interim periods presented; all such adjustments are of a normal recurring nature except for the impacts of adopting new accounting standards as discussed below. All significant intercompany accounts and transactions have been eliminated. The results of operations for the three-month interim period ended March 31, 2019 , are not necessarily indicative of the results of operations to be attained for the year ending December 31, 2019 . Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace’s accounting measurements that are most affected by management’s estimates of future events are: • Realization values of net deferred tax assets and the effective tax rate, which depend on projections of future taxable income; • Pension and postretirement liabilities, which depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 6); • Carrying values of goodwill and other intangible assets, which depend on assumptions of future earnings and cash flows; and • Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate obligation, such as litigation, environmental remediation, and other legacy liabilities (see Note 8). 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 August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20).” This update revises disclosure requirements related to defined benefit pension and other postretirement plans. Grace is required to adopt the amendments in this update on January 1, 2021. Grace is currently evaluating the timing of adoption and does not expect the update to have a material effect on the Consolidated Financial Statements. Recently Adopted Accounting Standards In October 2018, the FASB issued ASU 2018-16 “Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes.” This update permits use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under Topic 815. Grace currently carries debt and derivatives that rely on the London Interbank Offered Rate (“LIBOR”) as a benchmark rate. LIBOR is expected to be phased out as a benchmark rate by the end of 2021. Grace expects its debt and financial instruments to continue to use LIBOR until the rate is no longer available. To the extent LIBOR ceases to exist, Grace may need to renegotiate any credit agreements and/or derivative contracts that utilize LIBOR as a factor in determining the interest rate. Grace adopted this update in the 2019 first quarter, and it had no effect on Grace’s Consolidated Financial Statements. Leases (Topic 842) 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. 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 payments to be made in optional periods where they are reasonably certain to occur. In July 2018, the FASB issued ASU 2018-11 “Leases (Topic 842): Targeted Improvements,” which provides an additional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Grace adopted these standards in the 2019 first quarter under the modified retrospective approach permitted by ASU 2018-11. Under this approach, the cumulative effect of the adoption of the standard is recorded at the effective date, with no changes to prior periods. The adoption did not result in an impact to retained earnings. Grace elected to utilize the package of transition practical expedients provided by the standard, which among other things, permit Grace not to reassess expired or existing contracts and leases. Additionally, Grace elected to use the practical expedient provided in ASU 2018-01 “Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842,” which permits Grace to elect not to evaluate under Topic 842 existing or expired land easements not previously accounted for as leases. Prior to the adoption of Topic 842, Grace typically had not evaluated easements for lease accounting. Grace has elected not to recognize in the Consolidated Balance Sheets short-term leases, which are those with an initial term of 12 months or less. Grace has also elected not to separate lease and nonlease components. These elections apply to all asset classes. Adoption of the standard resulted in the recognition of operating lease right-of-use assets, net of accumulated amortization, of $29.4 million and operating lease liabilities of $30.0 million as of March 31, 2019 . (in millions) Amount Balance Sheet Location Operating lease right of use asset $ 29.4 Other assets Operating lease liability—current 8.7 Other current liabilities Operating lease liability—noncurrent 21.3 Other liabilities Grace leases certain real estate, office space, vehicles, railcars, and office equipment. For leases with an initial term of 12 months or less, Grace recognizes lease expense on a straight-line basis over the lease term. Finance lease costs and sublease income are not material. Many of Grace’s leases contain renewal options, which are exercisable at Grace’s discretion and may be included in lease terms when they are reasonably certain to be exercised. Grace’s lease agreements do not contain material restrictive covenants or material residual value guarantees. Where available, Grace uses the interest rate implicit in the lease to calculate the estimated present value of lease payment obligations. Where such a rate is not available, Grace uses an incremental borrowing rate based on credit-adjusted and term-specific discount rates, using a third-party yield curve. The following table presents Grace’s costs and cash flow information related to operating leases. (In millions) Three Months Ended March 31, 2019 Operating lease cost $ 3.0 Short-term and variable lease cost 3.4 Total lease cost $ 6.4 Cash payments related to operating leases $ 3.0 Right-of-use assets obtained in exchange for new operating lease liabilities 3.6 The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. March 31, Weighted average discount rate 6.8 % Weighted average remaining lease term 7.4 years The table below presents the maturities of operating lease liabilities at March 31, 2019 . (In millions) 2019 $ 8.0 2020 8.3 2021 5.4 2022 3.7 2023 2.2 Thereafter 11.2 Total undiscounted lease payments 38.8 Less: imputed interest 8.8 Present value of lease liabilities $ 30.0
Leases of Lessee Disclosure [Text Block]	Leases (Topic 842) 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. 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 payments to be made in optional periods where they are reasonably certain to occur. In July 2018, the FASB issued ASU 2018-11 “Leases (Topic 842): Targeted Improvements,” which provides an additional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Grace adopted these standards in the 2019 first quarter under the modified retrospective approach permitted by ASU 2018-11. Under this approach, the cumulative effect of the adoption of the standard is recorded at the effective date, with no changes to prior periods. The adoption did not result in an impact to retained earnings. Grace elected to utilize the package of transition practical expedients provided by the standard, which among other things, permit Grace not to reassess expired or existing contracts and leases. Additionally, Grace elected to use the practical expedient provided in ASU 2018-01 “Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842,” which permits Grace to elect not to evaluate under Topic 842 existing or expired land easements not previously accounted for as leases. Prior to the adoption of Topic 842, Grace typically had not evaluated easements for lease accounting. Grace has elected not to recognize in the Consolidated Balance Sheets short-term leases, which are those with an initial term of 12 months or less. Grace has also elected not to separate lease and nonlease components. These elections apply to all asset classes. Adoption of the standard resulted in the recognition of operating lease right-of-use assets, net of accumulated amortization, of $29.4 million and operating lease liabilities of $30.0 million as of March 31, 2019 . (in millions) Amount Balance Sheet Location Operating lease right of use asset $ 29.4 Other assets Operating lease liability—current 8.7 Other current liabilities Operating lease liability—noncurrent 21.3 Other liabilities Grace leases certain real estate, office space, vehicles, railcars, and office equipment. For leases with an initial term of 12 months or less, Grace recognizes lease expense on a straight-line basis over the lease term. Finance lease costs and sublease income are not material. Many of Grace’s leases contain renewal options, which are exercisable at Grace’s discretion and may be included in lease terms when they are reasonably certain to be exercised. Grace’s lease agreements do not contain material restrictive covenants or material residual value guarantees. Where available, Grace uses the interest rate implicit in the lease to calculate the estimated present value of lease payment obligations. Where such a rate is not available, Grace uses an incremental borrowing rate based on credit-adjusted and term-specific discount rates, using a third-party yield curve. The following table presents Grace’s costs and cash flow information related to operating leases. (In millions) Three Months Ended March 31, 2019 Operating lease cost $ 3.0 Short-term and variable lease cost 3.4 Total lease cost $ 6.4 Cash payments related to operating leases $ 3.0 Right-of-use assets obtained in exchange for new operating lease liabilities 3.6 The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. March 31, Weighted average discount rate 6.8 % Weighted average remaining lease term 7.4 years The table below presents the maturities of operating lease liabilities at March 31, 2019 . (In millions) 2019 $ 8.0 2020 8.3 2021 5.4 2022 3.7 2023 2.2 Thereafter 11.2 Total undiscounted lease payments 38.8 Less: imputed interest 8.8 Present value of lease liabilities $ 30.0

Inventories

Inventories	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 , and December 31, 2018 : (In millions) March 31, December 31, Raw materials $ 66.7 $ 56.3 In process 53.6 49.1 Finished products 163.3 144.5 Other 32.6 31.2 Total inventory $ 316.2 $ 281.1

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Components of Debt (In millions) March 31, December 31, 2018 U.S. dollar term loan, net of unamortized debt issuance costs of $8.4 (2018—$8.7) $ 936.8 $ 938.9 5.125% senior notes due 2021, net of unamortized debt issuance costs of $3.8 (2018—$4.2) 696.2 695.8 5.625% senior notes due 2024, net of unamortized debt issuance costs of $2.8 (2018—$3.0) 297.2 297.0 Debt payable to unconsolidated affiliate 47.7 48.1 Other borrowings(1) 6.2 3.5 Total debt 1,984.1 1,983.3 Less debt payable within one year 22.5 22.3 Debt payable after one year $ 1,961.6 $ 1,961.0 Weighted average interest rates on total debt 3.9 % 3.9 % ___________________________________________________________________________________________________________________ (1) Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries. See Note 4 for a discussion of the fair value of Grace’s debt. Grace also maintains a $400 million revolving credit facility. As of March 31, 2019 , the available credit under this facility was reduced to $369.1 million by outstanding letters of credit. The principal maturities of debt outstanding at March 31, 2019 , were as follows: (In millions) 2019 $ 17.5 2020 19.5 2021 714.3 2022 17.3 2023 16.3 Thereafter 1,199.2 Total debt $ 1,984.1

Fair Value Measurements and Ris

Fair Value Measurements and Risk	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 , and December 31, 2018 , the carrying amounts and fair values of Grace’s debt were as follows: 3/31/2019 12/31/2018 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 2018 U.S. dollar term loan(1) $ 936.8 $ 925.1 $ 938.9 $ 914.8 5.125% senior notes due 2021(2) 696.2 718.2 695.8 697.5 5.625% senior notes due 2024(2) 297.2 315.8 297.0 301.8 Other borrowings 53.9 53.9 51.6 51.6 Total debt $ 1,984.1 $ 2,013.0 $ 1,983.3 $ 1,965.7 ___________________________________________________________________________________________________________________ (1) Carrying amounts are net of unamortized debt issuance costs and discounts of $8.4 million and $8.7 million as of March 31, 2019 and December 31, 2018 , respectively. (2) Carrying amounts are net of unamortized debt issuance costs of $3.8 million and $2.8 million as of March 31, 2019 , and $4.2 million and $3.0 million as of December 31, 2018 , related to the 5.125% senior notes due 2021 and 5.625% senior notes due 2024, respectively. At March 31, 2019 , 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 70 countries and in over 30 currencies, its results are exposed to fluctuations in currency exchange rates. Grace seeks to minimize exposure to these fluctuations by matching sales with expenditures in the same currencies, but it is not always possible to do so. From time to time, Grace uses financial instruments such as currency forward contracts, options, swaps, or combinations thereof to reduce the risk of certain specific transactions. However, Grace does not have a policy of hedging all exposures, because management does not believe that such a level of hedging would be cost-effective. Forward contracts with maturities of not more than 36 months are used and designated as cash flow hedges of forecasted repayments of intercompany loans. The effective portion of gains and losses on these currency hedges is recorded in “accumulated other comprehensive income (loss)” and reclassified into “other (income) expense, net” to offset the remeasurement of the underlying hedged loans. Excluded components (forward points) on these hedges are amortized to income on a systematic basis. Grace also enters into foreign currency forward contracts and swaps to hedge a portion of its net outstanding monetary assets and liabilities. These forward contracts and swaps are not designated as hedging instruments under applicable accounting guidance, and therefore all changes in their fair value are recorded in “other (income) expense, net,” in the Consolidated Statements of Operations. These forward contracts and swaps are intended to offset the foreign currency gains or losses associated with the underlying monetary assets and liabilities. The valuation of Grace’s currency exchange rate forward contracts and swaps is determined using an income approach. Inputs used to value currency exchange rate forward contracts and swaps consist of: (1) spot rates, which are quoted by various financial institutions; (2) forward points, which are primarily affected by changes in interest rates; and (3) discount rates used to present value future cash flows, which are based on the London Interbank Offered Rate (LIBOR) curve or overnight indexed swap rates. Total notional amounts for forward contracts and swaps outstanding as of March 31, 2019 , were $188.7 million . Cross-Currency Swap Agreements Grace uses cross-currency swaps designated as cash flow hedges to manage fluctuations in currency exchange rates and interest rates on variable rate debt. The effective portion of gains and losses on these cash flow hedges is recorded in “accumulated other comprehensive income (loss)” and reclassified into “other (income) expense, net” and “interest expense and related financing costs” during the hedged period. In April 2018, in connection with the 2018 U.S. dollar term loan, Grace entered into cross-currency swaps beginning on April 3, 2018, and maturing on March 31, 2023, to synthetically convert $600.0 million of U.S. dollar-denominated floating rate debt into €490.1 million of euro-denominated debt fixed at 2.0231% . These cross-currency swaps were de-designated and terminated on November 5, 2018, and replaced with new, at-market cross-currency swaps beginning on November 5, 2018, and maturing on March 31, 2023, to synthetically convert $600.0 million of U.S. dollar-denominated floating rate debt into €525.9 million of euro-denominated debt fixed at 1.785% . The valuation of these cross-currency swaps is determined using an income approach, using LIBOR and EURIBOR (Euro Interbank Offered Rate) swap curves, currency basis spreads, and euro/U.S. dollar exchange rates. Debt and Interest Rate Swap Agreements Grace uses interest rate swaps designated as cash flow hedges to manage fluctuations in interest rates on variable rate debt. The effective portion of gains and losses on these interest rate cash flow hedges is recorded in “accumulated other comprehensive income (loss)” and reclassified into “interest expense and related financing costs” during the hedged 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 $250.0 million of Grace’s term debt at a rate of 2.393% . These interest rate swaps were de-designated and terminated in April 2018 in connection with Grace’s entry into a new credit agreement. In connection with the 2018 U.S. dollar term loan, Grace entered into new interest rate swaps beginning on April 3, 2018, and maturing on March 31, 2023, fixing the LIBOR component of the interest on $100.0 million of term debt at 2.775% . The valuation of these interest rate swaps is determined using an income approach, using prevailing market interest rates and discount rates to present value future cash flows based on the forward LIBOR yield curves. Credit risk is also incorporated into derivative valuations. The following tables present the fair value hierarchy for financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2019 , and December 31, 2018 : Fair Value Measurements at March 31, 2019, 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 $ 5.5 $ — $ 5.5 $ — Variable-to-fixed cross-currency swaps 0.8 — 0.8 — Total Assets $ 6.3 $ — $ 6.3 $ — Liabilities Currency derivatives $ 4.3 $ — $ 4.3 $ — Interest rate derivatives 1.9 — 1.9 — Total Liabilities $ 6.2 $ — $ 6.2 $ — Fair Value Measurements at December 31, 2018, 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 $ 3.7 $ — $ 3.7 $ — Total Assets $ 3.7 $ — $ 3.7 $ — Liabilities Currency derivatives $ 10.5 $ — $ 10.5 $ — Interest rate derivatives 0.8 — 0.8 — Variable-to-fixed cross-currency swaps 3.6 — 3.6 — Total Liabilities $ 14.9 $ — $ 14.9 $ — The following tables present the location and fair values of derivative instruments included in the Consolidated Balance Sheets as of March 31, 2019 , and December 31, 2018 : March 31, 2019 Asset Derivatives Liability Derivatives 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 assets $ (3.1 ) Interest rate contracts Other current assets — Other current liabilities 0.3 Variable-to-fixed cross-currency swaps Other current assets 14.6 Other current liabilities — Currency contracts Other assets 2.6 Other liabilities 7.4 Interest rate contracts Other assets — Other liabilities 1.6 Variable-to-fixed cross-currency swaps Other liabilities (13.8 ) Other liabilities — Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.5 Other current liabilities — Currency contracts Other current liabilities (0.3 ) Other liabilities — Total derivatives $ 6.3 $ 6.2 December 31, 2018 Asset Derivatives Liability Derivatives Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.4 Other current assets $ (2.9 ) Interest rate contracts Other current assets — Other current liabilities 0.1 Variable-to-fixed cross-currency swaps Other current assets — Other current assets (15.4 ) Currency contracts Other assets 1.3 Other liabilities 12.9 Interest rate contracts Other assets — Other liabilities 0.7 Variable-to-fixed cross-currency swaps Other assets — Other liabilities 19.0 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets — Other current assets (0.1 ) Currency contracts Other current assets — Other current liabilities 0.6 Total derivatives $ 3.7 $ 14.9 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 three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (1.1 ) Interest expense $ — Currency contracts(1) 1.6 Other expense 1.3 Variable-to-fixed cross-currency swaps 0.1 Interest expense 3.6 Variable-to-fixed cross-currency swaps 8.4 Other expense 8.4 Total derivatives $ 9.0 $ 13.3 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (0.1 ) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $0.0 million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Three Months Ended March 31, 2018 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 1.5 Interest expense $ (0.2 ) Currency contracts(1) (6.6 ) Other expense (6.1 ) Total derivatives $ (5.1 ) $ (6.3 ) Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (1.4 ) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.8) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. The following table presents the total amounts of income and expense line items presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are reported. Three Months Ended March 31, 2019 2018 (In millions) 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 $ (20.0 ) $ 2.2 $ (19.3 ) $ 3.3 Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Amount of gain (loss) reclassified from accumulated OCI into income $ — $ — $ (0.2 ) $ — Variable-to-fixed cross-currency swaps Amount of gain (loss) reclassified from accumulated OCI into income 3.6 8.4 — — Currency contracts Amount of gain (loss) reclassified from accumulated OCI into income — 1.3 — (6.1 ) Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 0.7 — 0.9 Net Investment Hedges Grace uses cross-currency swaps as derivative hedging instruments in certain net investment hedges of its non-U.S. subsidiaries. The gains and losses attributable to these net investment hedges, adjusted for the impact of excluded components, are recorded net of tax to “currency translation adjustments” within “accumulated other comprehensive income (loss)” to offset the change in the carrying value of the net investment being hedged. Recognition in earnings of amounts previously recorded to “currency translation adjustments” is limited to circumstances such as complete or substantially complete liquidation of the net investment in the hedged foreign operation. Changes in the fair value of the hedging instrument related to time value, which are excluded from the assessment of hedge effectiveness, are recorded directly to interest expense on a systematic basis. These gains were $0.8 million for the three months ended March 31, 2019 . At March 31, 2019 , 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. At March 31, 2019 , €5.6 million of Grace’s deferred intercompany royalties was designated as a hedging instrument of its net investment in its European subsidiaries. In April 2018, in connection with the Credit Agreement, Grace de-designated and repaid its euro-denominated term loan principal that had been designated as a hedge of its net investment in its European subsidiaries. The following table presents the amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges, recorded to “currency translation adjustments” within “accumulated other comprehensive income (loss)” for the three months ended March 31, 2019 and 2018 . There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented. Three Months Ended March 31, (In millions) 2019 2018 Derivatives in ASC 815 net investment hedging relationships: Cross-currency swaps $ 3.8 $ (11.3 ) Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ — $ (4.4 ) Foreign currency denominated deferred intercompany royalties 0.1 (1.7 ) $ 0.1 $ (6.1 ) Credit Risk Grace is exposed to credit risk in its trade accounts receivable. Grace’s credit evaluation policies mitigate credit risk exposures, and it has a history of minimal credit losses. Grace does not generally require collateral for its trade accounts receivable, but may require a bank letter of credit in certain instances, particularly when selling to customers in cash-restricted countries.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Grace’s effective tax rates for the three months ended March 31, 2019 and 2018 , were 30.7% and 36.4% , respectively. For both periods, Grace’s effective tax rate was higher than the U.S. federal statutory rate primarily due to the effect of taxes in foreign jurisdictions. Additionally, the 2018 provision for income taxes includes a Global Intangible Low-Taxed Income (“GILTI”) charge on income earned by certain foreign subsidiaries of $5.9 million . The effect of the GILTI charge on the 2019 provision for income taxes is immaterial because Grace forecasts U.S. federal taxable income and expects to significantly utilize its remaining U.S. net operating losses in 2019. This would allow Grace to benefit from the GILTI deduction in 2019, while it could not in 2018 because it had insufficient U.S. federal taxable income. As of March 31, 2019, Grace has $301.2 million in federal tax credit carryforwards before unrecognized tax benefits. Based on the status of examinations in our significant taxing jurisdictions, Grace expects that the amount of the liability for unrecognized tax benefits could decrease by approximately $3 million to $5 million

Pension Plans and Other Postret

Pension Plans and Other Postretirement Benefit Plans	3 Months Ended
	Mar. 31, 2019
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension Plans and Other Postretirement Benefit Plans	Pension Plans The following table presents the funded status of Grace’s pension plans: (In millions) March 31, December 31, Overfunded defined benefit pension plans $ 5.9 $ 5.7 Underfunded defined benefit pension plans (67.6 ) (67.1 ) Unfunded defined benefit pension plans (362.9 ) (366.0 ) Total underfunded and unfunded defined benefit pension plans (430.5 ) (433.1 ) Pension liabilities included in other current liabilities (14.6 ) (14.7 ) Net funded status $ (439.2 ) $ (442.1 ) Fully-funded plans include several advance-funded plans where the fair value of the plan assets exceeds the projected benefit obligation ("PBO"). Underfunded plans include a group of advance-funded plans that are underfunded on a PBO basis. Unfunded plans include several plans that are funded on a pay-as-you-go basis, and therefore, the entire PBO is unfunded. The following table presents the components of net periodic benefit cost (income). Three Months Ended March 31, 2019 2018 (In millions) U.S. Non-U.S. U.S. Non-U.S. Service cost $ 3.9 $ 2.2 $ 4.8 $ 2.4 Interest cost 9.6 1.3 10.3 1.3 Expected return on plan assets (12.0 ) (0.2 ) (14.5 ) (0.3 ) Amortization of prior service credit (0.2 ) — (0.2 ) — Net periodic benefit cost (income) $ 1.3 $ 3.3 $ 0.4 $ 3.4 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. Grace intends to fund non-U.S. pension plans based on applicable legal requirements and actuarial recommendations. 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 for the three months ended March 31, 2019 , was $3.3 million compared with $2.8 million for the prior-year quarter .

Other Balance Sheet Accounts

Other Balance Sheet Accounts	3 Months Ended
	Mar. 31, 2019
Other Balance Sheet Accounts [Abstract]
Other Balance Sheet Accounts	(In millions) March 31, December 31, Other Current Assets Plant under construction—unconsolidated affiliate (see Note 15) $ 114.5 $ — Non-trade accounts receivable 31.4 37.9 Fair value of currency, interest rate, and commodity contracts (see Note 4) 21.2 21.4 Income taxes receivable 19.4 10.1 Other current assets 16.3 17.3 $ 202.8 $ 86.7 (In millions) March 31, December 31, Other Current Liabilities Liability to unconsolidated affiliate for plant under construction (see Note 15) $ 114.5 $ — Deferred revenue (see Note 13) 41.4 40.6 Accrued compensation 34.9 62.4 Accrued interest (see Note 3) 26.4 13.3 Environmental contingencies (see Note 8) 20.8 19.5 Income taxes payable (see Note 5) 18.0 11.3 Pension liabilities (see Note 6) 14.6 14.7 Operating lease liabilities (see Note 1) 8.7 — Liability for dam spillway replacement (see Note 8) 4.2 — Other accrued liabilities 72.5 81.7 $ 356.0 $ 243.5 Accrued compensation includes salaries and wages as well as estimated current amounts due under the annual and long-term incentive programs. (In millions) March 31, December 31, Other Liabilities Environmental contingencies (see Note 8) $ 102.6 $ 106.9 Liability for dam spillway replacement (see Note 8) 40.8 — Deferred revenue (see Note 13) 24.4 29.2 Fair value of currency and interest rate contracts (see Note 4) 22.8 32.6 Operating lease liabilities (see Note 1) 21.3 — Deferred income taxes 10.8 10.9 Asset retirement obligation 8.9 8.8 Postemployment liability 4.6 4.7 Liability to unconsolidated affiliate for plant under construction (see Note 15) — 98.8 Other noncurrent liabilities 28.3 27.9 $ 264.5 $ 319.8

Commitments and Contingent Liab

Commitments and Contingent Liabilities	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Legacy Matters Over the years, Grace operated numerous types of businesses that are no longer part of its ongoing operations. As Grace divested or otherwise ceased operating these businesses, it retained certain liabilities and obligations, which Grace refers to as legacy liabilities. These liabilities include product, environmental and other liabilities. Although the outcome of each of the matters discussed below cannot be predicted with certainty, Grace has assessed its risk and has recorded estimated liabilities as required under U.S. GAAP. Legacy Product Liabilities Grace emerged from an asbestos-related Chapter 11 bankruptcy on February 3, 2014 (the “Effective Date”). Under its plan of reorganization, all pending and future asbestos-related claims are channeled for resolution to either a personal injury trust (the “PI Trust”) or a property damage trust (the “PD Trust”). The trusts are the sole recourse for holders of asbestos-related claims. The channeling injunctions issued by the bankruptcy court prohibit holders of asbestos-related claims from asserting such claims directly against Grace. Grace has satisfied all of its financial obligations to the PI Trust. Grace has contingent financial obligations remaining to the PD Trust. With respect to property damage claims related to Grace’s former Zonolite attic insulation product 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. The PD Trust balance was approximately $30 million as of December 31, 2018. Grace expects ZAI PD Claims payments to decline over time but has limited information to estimate the amount and timing of future claims payments. It is reasonably possible that one or more contingent deferred payments will be made in the future. Grace estimates the present value of reasonably possible future payments to range between $0 million and $20 million . Grace has not accrued for any contingent deferred payments as it does not believe that payment is probable. Grace will continue to evaluate new information as it becomes available and will revise its estimate of the amount and timing of future claims payments and any contingent deferred payments at that time. 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 and are readily available on the internet at www.sec.gov. Legacy Environmental Liabilities Grace is subject to loss contingencies resulting from extensive and evolving federal, state, local and foreign environmental laws and regulations relating to its manufacturing operations. Grace has procedures in place to minimize such contingencies; nevertheless, it has liabilities associated with past operations and additional claims may arise in the future, which may be material. To address its legacy liabilities, Grace accrues for anticipated costs of response efforts where an assessment has indicated that a probable liability has been incurred and the cost can be reasonably estimated. These accruals do not take into account any discounting for the time value of money. Grace’s environmental liabilities are reassessed regularly and adjusted when circumstances become better defined or response efforts and their costs can be better estimated, typically as a matter moves through the life-cycle of environmental investigation and remediation. These liabilities are evaluated based on currently available information relating to the nature and extent of contamination, risk assessments, feasibility of response actions, and apportionment amongst other potentially responsible parties, all evaluated in light of prior experience. At March 31, 2019 , Grace’s estimated liability for legacy environmental response costs totaled $123.4 million , compared with $126.4 million at December 31, 2018 , 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. Vermiculite-Related Matters Grace purchased a vermiculite mine in Libby, Montana, in 1963 and operated it until 1990. Vermiculite concentrate from the Libby mine was used in the manufacture of attic insulation and other products. Some of the vermiculite ore contained naturally occurring asbestos. Grace is engaged with the U.S. Environmental Protection Agency (the “EPA”) and other federal, state, and local governmental agencies in a remedial investigation and feasibility study (“RI/FS”) of the Libby mine and the surrounding area, known as Operable Unit 3 (“OU3”). The RI/FS will determine the specific areas within OU3 requiring remediation and will identify possible remedial action alternatives. Possible remedial actions within OU3 are wide-ranging, from institutional controls such as land use restrictions, to more active measures involving soil removal, containment projects, or other protective measures. As part of the RI/FS process, Grace contracted an engineering and consulting firm to develop a range of possible remedial alternatives and associated cost estimates for OU3. Based on this work, Grace recorded a pre-tax charge of $70.0 million in the 2018 third quarter for the estimated costs of remediation of OU3. Grace believes that this amount should provide for a protective remedy meeting the statutory requirements of the Comprehensive Environmental Response, Compensation, and Liability Act. The estimated costs of remediation are preliminary and consist of several components, each of which may vary significantly as the remedial alternatives are further developed. It is reasonably possible that the ultimate costs of remediation could range between $30 million and $170 million . Grace is working closely with the EPA, and the ultimate remedy will be determined by the EPA after the RI/FS is finalized. Such remedy will be set forth in a Record of Decision (“ROD”) that is expected to be issued by the EPA during 2021. Costs associated with the more active remedial alternatives would be expected to be incurred over a decade or more. Grace will reevaluate its estimated liability as remedial alternatives evolve based on further work by the engineering and consulting firm and discussions with the EPA as the RI/FS process moves toward a ROD. Depending on the remedial alternatives that the EPA selects in the ROD, the total cost of remediating OU3 may exceed Grace’s current estimate by material amounts. The 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’s total estimated liability for response costs that are currently estimable for OU3 and vermiculite processing sites outside of Libby at March 31, 2019 , and December 31, 2018 , was $80.7 million and $81.7 million , respectively. It is possible that Grace’s ultimate liability for these vermiculite-related matters will exceed current estimates by material amounts. Non-Vermiculite-Related Environmental Matters At March 31, 2019 , and December 31, 2018 , Grace’s estimated legacy environmental liability for response costs at sites not related to its former vermiculite mining and processing activities was $42.7 million and $44.7 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. Other Legacy Liabilities On April 3, 2019, the Montana Department of Natural Resources and Conservation issued a five-year operating permit for a dam at the Libby mine site. Grace constructed the dam in 1971 to prevent vermiculite ore tailings from moving into nearby creeks and rivers. The permit requires Grace to complete construction of a new spillway before the permit is further renewed in five years. Grace contracted a third-party engineering and consulting firm to develop a range of cost estimates for the project. Based on this work, Grace recorded a pre-tax charge of $45.0 million in the first quarter of 2019 for the estimated costs of the project. These costs are preliminary and may vary significantly as the project progresses. It is reasonably possible that the ultimate costs of this project could range between $25 million and $80 million . Construction of the new spillway is expected to take three to four years . Commercial and Financial Commitments and Contingencies Purchase Commitments Grace uses purchase commitments to ensure supply and to minimize the volatility of major components of direct manufacturing costs including natural gas, certain metals, rare earths, and other materials. Such commitments are for quantities that Grace fully expects to use in its normal operations. Guarantees and Indemnification Obligations Grace is a party to many contracts containing guarantees and indemnification obligations. These contracts primarily consist of: • Product warranties with respect to certain products sold to customers in the ordinary course of business. These warranties typically provide that products will conform to specifications. Grace accrues a warranty liability on a transaction-specific basis depending on the individual facts and circumstances related to each sale. • Performance guarantees offered to customers under certain licensing arrangements. Grace has not established a liability for these arrangements based on past performance. • Licenses of intellectual property by Grace to third parties in which Grace has agreed to indemnify the licensee against third party infringement claims. • Contracts providing for the sale or spin-off of a former business unit or product line in which Grace has agreed to indemnify the buyer or resulting entity against certain liabilities related to activities prior to the closing of the transaction, including environmental, tax, and employee liabilities. • 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. As of March 31, 2019 , Grace had gross financial assurances issued and outstanding of $146.1 million , composed of $68.7 million of surety bonds issued by various insurance companies and $77.4 million

Restructuring Expenses and Repo

Restructuring Expenses and Repositioning Expenses	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Restructuring Expenses and Repositioning Expenses	Restructuring Expenses Restructuring costs in 2019 primarily related to severance costs pertaining to sales force reorganization. Restructuring costs in 2018 primarily related to plant exit costs and severance costs pertaining to sales force reorganization. These costs are included in “restructuring and repositioning expenses” in the Consolidated Statements of Operations, and are not included in segment operating income. The following table presents restructuring expenses by reportable segment for the three months ended March 31, 2019 and 2018 . Three Months Ended March 31, (In millions) 2019 2018 Catalysts Technologies $ 0.2 $ 0.4 Materials Technologies 1.0 0.4 Corporate (0.1 ) 0.2 Total restructuring expenses $ 1.1 $ 1.0 The following table presents components of the change in the restructuring liability from December 31, 2018 , to March 31, 2019 . (In millions) Balance, December 31, 2018 $ 10.7 Accruals for severance and other costs 1.1 Payments (3.0 ) Balance, March 31, 2019 $ 8.8 Substantially all costs related to the restructuring programs are expected to be paid by December 31, 2021, but could be paid earlier subject to negotiations around certain plant exit costs. Repositioning Expenses Repositioning expenses for the three months ended March 31, 2019 , were $1.2 million compared with $4.6 million for the prior-year quarter

Other (Income) Expense, net

Other (Income) Expense, net	3 Months Ended
	Mar. 31, 2019
Other Income and Expenses [Abstract]
Other (Income) Expense, net	Components of other (income) expense, net are as follows: Three Months Ended March 31, (In millions) 2019 2018 Defined benefit pension (income) expense other than service cost $ (1.5 ) $ (3.4 ) Third-party acquisition-related costs 0.3 0.9 Currency transaction effects (0.2 ) (0.9 ) Net (gain) loss on sales of investments and disposals of assets 0.5 0.4 Other miscellaneous (income) expense (1.3 ) (0.3 ) Total other (income) expense, net $ (2.2 ) $ (3.3 )

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 31, 2019
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 three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 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 $ (0.2 ) $ — $ (0.2 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.1 — 0.1 Benefit plans, net (0.1 ) — (0.1 ) Currency translation adjustments 12.9 (1.2 ) 11.7 Gain (loss) from hedging activities (4.3 ) 1.3 (3.0 ) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 8.5 $ 0.1 $ 8.6 Three Months Ended March 31, 2018 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 $ (0.4 ) $ 0.1 $ (0.3 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.1 — 0.1 Benefit plans, net (0.3 ) 0.1 (0.2 ) Currency translation adjustments (20.8 ) 2.6 (18.2 ) Gain (loss) from hedging activities 2.2 (0.4 ) 1.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (18.9 ) $ 2.3 $ (16.6 ) The following tables present the changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Beginning balance $ 0.2 $ 76.2 $ (8.5 ) $ 67.9 Other comprehensive income (loss) before reclassifications — 11.7 6.6 18.3 Amounts reclassified from accumulated other comprehensive income (loss) (0.1 ) — (9.6 ) (9.7 ) Net current-period other comprehensive income (loss) (0.1 ) 11.7 (3.0 ) 8.6 Ending balance $ 0.1 $ 87.9 $ (11.5 ) $ 76.5 Three Months Ended March 31, 2018 Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Beginning balance $ 0.9 $ 41.6 $ (2.6 ) $ 39.9 Other comprehensive income (loss) before reclassifications — (18.2 ) (5.4 ) (23.6 ) Amounts reclassified from accumulated other comprehensive income (loss) (0.2 ) — 7.2 7.0 Net current-period other comprehensive income (loss) (0.2 ) (18.2 ) 1.8 (16.6 ) Ending balance $ 0.7 $ 23.4 $ (0.8 ) $ 23.3 Grace is a global enterprise operating in many countries with local currency generally deemed to be the functional currency for accounting purposes. The currency translation amount represents the adjustments necessary to translate the balance sheets valued in local currencies to the U.S. dollar as of the end of each period presented, and to translate revenues and expenses at average exchange rates for each period presented.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
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. Three Months Ended March 31, (In millions, except per share amounts) 2019 2018 Numerators Net income (loss) attributable to W. R. Grace & Co. shareholders $ 24.7 $ 43.6 Denominators Weighted average common shares—basic calculation 66.8 67.6 Dilutive effect of employee stock options 0.1 0.1 Weighted average common shares—diluted calculation 66.9 67.7 Basic earnings per share $ 0.37 $ 0.64 Diluted earnings per share $ 0.37 $ 0.64 There were 0.9 million anti-dilutive options outstanding for the three months ended March 31, 2019 , compared with 1.7 million for the prior-year quarter . On February 8, 2017, the Company announced that its Board of Directors authorized a share repurchase program of up to $250 million . The timing of the repurchases and the actual amount repurchased will depend on a variety of factors, including the market price of the Company’s shares, strategic priorities for the deployment of capital, and general market and economic conditions. During the three months ended March 31, 2019 and 2018 , the Company repurchased 69,860 shares and 514,141 shares of Company common stock for $4.8 million and $35.0 million , respectively, pursuant to the terms of the share repurchase program. As of March 31, 2019 , $134.1 million

Revenues

Revenues	3 Months Ended
	Mar. 31, 2019
Revenues [Abstract]
Revenues	Grace generates revenues from customer arrangements primarily by manufacturing and delivering specialty chemicals, specialty materials and the licensing of technology through its two reportable segments. See Note 14 for additional information about Grace’s reportable segments. Disaggregation of Revenue The following tables present Grace's revenues by geography and product group, within its respective reportable segments, for the three months ended March 31, 2019 and 2018 . Three Months Ended March 31, 2019 North America Europe Middle East Africa (EMEA) Asia Pacific Latin America Total Refining Catalysts $ 72.2 $ 66.6 $ 35.7 $ 7.3 $ 181.8 Polyolefin and Chemical Catalysts 45.8 64.9 52.4 4.8 167.9 Total Catalysts Technologies 118.0 131.5 88.1 12.1 349.7 Coatings 7.0 19.7 9.4 2.1 38.2 Consumer/Pharma 9.3 19.0 4.0 4.7 37.0 Chemical process 9.0 19.9 7.7 2.3 38.9 Other 1.2 4.5 — — 5.7 Total Materials Technologies 26.5 63.1 21.1 9.1 119.8 Total Grace $ 144.5 $ 194.6 $ 109.2 $ 21.2 $ 469.5 Three Months Ended March 31, 2018 North America EMEA Asia Pacific Latin America Total Refining Catalysts $ 69.9 $ 61.3 $ 38.8 $ 13.4 $ 183.4 Polyolefin and Chemical Catalysts 32.2 58.4 38.0 3.8 132.4 Total Catalysts Technologies 102.1 119.7 76.8 17.2 315.8 Coatings 7.1 20.5 11.8 $ 2.3 $ 41.7 Consumer/Pharma 7.7 13.2 4.3 4.7 29.9 Chemical process 7.4 20.8 7.2 2.3 37.7 Other 1.7 4.5 0.1 0.1 6.4 Total Materials Technologies 23.9 59.0 23.4 9.4 115.7 Total Grace $ 126.0 $ 178.7 $ 100.2 $ 26.6 $ 431.5 Contract Balances Grace invoices customers for product sales once performance obligations have been satisfied, generally at the point of delivery, at which point payment becomes unconditional. Accordingly, Grace's product sales contracts generally do not give rise to material contract assets or liabilities under ASC 606; however, from time to time certain customers may pay in advance. In the technology licensing business, Grace invoices licensees based on milestones achieved but has obligations to provide services in future periods, which results in contract liabilities. The following table presents Grace’s deferred revenue balances as of March 31, 2019 , and December 31, 2018 : (In millions) March 31, December 31, Current $ 41.4 $ 40.6 Noncurrent 24.4 29.2 Total $ 65.8 $ 69.8 These amounts are included as deferred revenue in “other current liabilities” and “other liabilities” in Grace's Consolidated Balance Sheets. Grace records deferred revenues when cash payments are received or billed and due in advance of performance. The change in deferred revenue reflects cash payments from customers received or due in advance of satisfying performance obligations, offset by $9.6 million of revenue recognized for the three months ended March 31, 2019 , that was included in the deferred revenue balance as of December 31, 2018 . The noncurrent portion of deferred revenue will be recognized as performance obligations under the technology licensing agreements are satisfied, which is expected to be over the next three years . Remaining performance obligations represent the estimated revenue expected to be recognized in the future related to performance obligations that are unsatisfied (or partially unsatisfied). The aggregate amount of the transaction price allocated to remaining performance obligations for such contracts with a duration of more than one year was approximately $113 million as of March 31, 2019 , and includes certain amounts reported as deferred revenue above. In accordance with the available practical expedient, Grace does not disclose information about remaining performance obligations that have original expected durations of one year or less, which generally relate to customer prepayments on product sales and are generally satisfied in less than one year. Grace expects to recognize revenue related to remaining performance obligations over several years, as follows: Year Approximate percentage of revenue related to remaining performance obligations recognized 2019 31 % 2020 23 % 2021 20 % Thereafter through 2025 26 % 100 % For the three months ended March 31, 2019 and 2018

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
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 15.) 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 consumer/pharma, chemical process, and coatings applications. The table below presents information related to Grace’s reportable segments. Only those corporate expenses directly related to the reportable segments are allocated for reporting purposes. All remaining corporate items are reported separately and labeled as such. Grace excludes defined benefit pension expense from the calculation of segment operating income. Grace believes that the exclusion of defined benefit pension expense provides a better indicator of its reportable segment performance as defined benefit pension expense is not managed at a reportable segment level. Grace defines Adjusted EBIT to be net income attributable to W. R. Grace & Co. shareholders adjusted for interest income and expense; income taxes; costs related to legacy matters; restructuring and repositioning expenses and asset impairments; pension costs other than service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits; gains and losses on sales 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 Three Months Ended March 31, (In millions) 2019 2018 Net Sales Catalysts Technologies $ 349.7 $ 315.8 Materials Technologies 119.8 115.7 Total $ 469.5 $ 431.5 Adjusted EBIT Catalysts Technologies segment operating income $ 101.4 $ 92.1 Materials Technologies segment operating income 24.0 24.1 Corporate costs (16.2 ) (16.6 ) Certain pension costs (4.8 ) (3.8 ) Total $ 104.4 $ 95.8 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 three months ended March 31, 2019 and 2018 , is reconciled below to “income (loss) before income taxes” presented in the accompanying Consolidated Statements of Operations. Three Months Ended March 31, (In millions) 2019 2018 Grace Adjusted EBIT $ 104.4 $ 95.8 Costs related to legacy matters (46.9 ) (2.0 ) Restructuring and repositioning expenses (2.3 ) (5.6 ) Third-party acquisition-related costs (0.3 ) (0.9 ) Interest expense, net (19.3 ) (18.9 ) Net income (loss) attributable to noncontrolling interests (0.1 ) (0.2 ) Income (loss) before income taxes $ 35.5 $ 68.2 Geographic Area Data The table below presents information related to the geographic areas in which Grace operates. Sales are attributed to geographic areas based on the location to which the product is transported. Three Months Ended March 31, (In millions) 2019 2018 Net Sales United States $ 131.6 $ 112.4 Canada 12.9 13.6 Total North America 144.5 126.0 Europe Middle East Africa 194.6 178.7 Asia Pacific 109.2 100.2 Latin America 21.2 26.6 Total $ 469.5 $ 431.5

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Affiliate	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 $159.5 million and $156.1 million as of March 31, 2019 , and December 31, 2018 , respectively. The amount of ART’s earnings included in “equity in earnings of unconsolidated affiliate” in the accompanying Consolidated Statements of Operations totaled $4.1 million for the three months ended March 31, 2019 , compared with $5.4 million for the prior-year quarter . ART is a private, limited liability company, taxed as a partnership, and accordingly does not have a quoted market price available. The table below presents summary financial data related to ART’s balance sheet and results of operations. (In millions) March 31, December 31, Summary Balance Sheet information: Current assets $ 307.8 $ 307.4 Noncurrent assets 177.0 160.2 Total assets $ 484.8 $ 467.6 Current liabilities $ 168.5 $ 158.3 Noncurrent liabilities 0.3 0.3 Total liabilities $ 168.8 $ 158.6 Three Months Ended March 31, (In millions) 2019 2018 Summary Statement of Operations information: Net sales $ 111.5 $ 85.2 Costs and expenses applicable to net sales 97.3 70.7 Income before income taxes 9.7 11.3 Net income 9.2 11.5 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 manufactured by Grace 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. Three Months Ended March 31, (In millions) 2019 2018 Product manufactured for ART $ 66.8 $ 51.9 Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold 1.3 1.0 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 12.8 10.7 The table below presents balances in Grace’s Consolidated Financial Statements related to ART. (in millions) March 31, December 31, Accounts receivable $ 12.9 $ 16.2 Current asset 114.5 — Noncurrent asset — 98.8 Accounts payable 27.7 32.0 Debt payable within one year 9.8 9.8 Debt payable after one year 37.9 38.3 Current liability 114.5 — Noncurrent liability — 98.8 The current asset and current liability (which were classified as noncurrent as of December 31, 2018) in the table above represent spending to date related to a residue hydroprocessing catalyst production plant that is under construction in Lake Charles, Louisiana. Grace manages the design and construction of the plant, and the asset will continue to be included in “other current 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 current liabilities” in the Consolidated Balance Sheets. Grace and ART maintain an agreement whereby ART loans Grace funds for maintenance capital expenditures at manufacturing facilities used to produce catalysts for ART. Grace makes principal and interest payments on the loans on a monthly basis. These unsecured loans have repayment terms of up to eight years , unless earlier repayment is demanded by ART. The loans bear interest at the three-month LIBOR plus 1.25% . Grace and Chevron provide lines of credit in the amount of $15.0 million each at a commitment fee of 0.1% of the credit amount. These agreements have been approved by the ART Executive Committee for renewal until February 2020. No amounts were outstanding at March 31, 2019 , and December 31, 2018 . Joint Venture Arrangement In 2018, Grace formed a joint venture in a developing country in Asia. The purpose of the joint venture is to establish a logistics facility and catalyst testing laboratory and to be the exclusive FCC catalysts and additives supplier to certain customers in the country. Grace’s joint venture partner is the parent company of the customers. Grace has an 87.5% ownership interest in the joint venture and consolidates the activities of the entity. Grace’s Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 , include trade accounts receivable of $3.2 million and $3.7 million , respectively, from these customers. Grace’s Consolidated Statement of Operations for the three months ended March 31, 2019 , includes $3.2 million of revenues from these customers. Grace did not have sales to these customers in the prior-year quarter

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2019
Business Combinations [Abstract]
Acquisitions	On April 3, 2018, using cash on hand and borrowings under the 2018 U.S. dollar term loan, Grace acquired the assets of the polyolefin catalysts business of Albemarle Corporation. Grace acquired the business for $418.0 million , net of cash acquired and including customary post-closing adjustments. The business is included in the Specialty Catalysts operating segment of the Catalysts Technologies reportable segment. The acquisition is complementary to Grace's existing specialty catalysts business and strengthens Grace's commercial relationships, catalysts technology portfolio, and manufacturing network. The acquisition purchase price has been allocated to the tangible and identifiable intangible assets and liabilities 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 purchase price allocation has been finalized, and during the measurement period, Grace recorded adjustments related to deferred taxes, working capital, and intangible assets. The goodwill recognized was $140.6 million and is supported by the expected growth and operating synergies that Grace expects to realize from this acquisition. The full amount of goodwill generated will be deductible for U.S. income tax purposes. The Consolidated Statement of Operations for the three months ended March 31, 2019, includes approximately $25 million

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The interim Consolidated Financial Statements presented herein are unaudited and should be read in conjunction with the Consolidated Financial Statements presented in the Company’s 2018 Annual Report on Form 10-K. Such interim Consolidated Financial Statements reflect all adjustments that, in the opinion of management, are necessary for a fair statement of the results of the interim periods presented; all such adjustments are of a normal recurring nature except for the impacts of adopting new accounting standards as discussed below. All significant intercompany accounts and transactions have been eliminated. The results of operations for the three-month interim period ended March 31, 2019 , are not necessarily indicative of the results of operations to be attained for the year ending December 31, 2019
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace’s accounting measurements that are most affected by management’s estimates of future events are: • Realization values of net deferred tax assets and the effective tax rate, which depend on projections of future taxable income; • Pension and postretirement liabilities, which depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 6); • Carrying values of goodwill and other intangible assets, which depend on assumptions of future earnings and cash flows; and •
Reclassifications	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 and Adopted Accounting Standards	Recently Issued Accounting Standards In August 2018, the FASB issued ASU 2018-14 “Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20).” This update revises disclosure requirements related to defined benefit pension and other postretirement plans. Grace is required to adopt the amendments in this update on January 1, 2021. Grace is currently evaluating the timing of adoption and does not expect the update to have a material effect on the Consolidated Financial Statements. Recently Adopted Accounting Standards In October 2018, the FASB issued ASU 2018-16 “Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes.” This update permits use of the OIS rate based on SOFR as a U.S. benchmark interest rate for hedge accounting purposes under Topic 815. Grace currently carries debt and derivatives that rely on the London Interbank Offered Rate (“LIBOR”) as a benchmark rate. LIBOR is expected to be phased out as a benchmark rate by the end of 2021. Grace expects its debt and financial instruments to continue to use LIBOR until the rate is no longer available. To the extent LIBOR ceases to exist, Grace may need to renegotiate any credit agreements and/or derivative contracts that utilize LIBOR as a factor in determining the interest rate. Grace adopted this update in the 2019 first quarter, and it had no effect on Grace’s Consolidated Financial Statements. Leases (Topic 842) 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. 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 payments to be made in optional periods where they are reasonably certain to occur. In July 2018, the FASB issued ASU 2018-11 “Leases (Topic 842): Targeted Improvements,” which provides an additional transition method that allows entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Grace adopted these standards in the 2019 first quarter under the modified retrospective approach permitted by ASU 2018-11. Under this approach, the cumulative effect of the adoption of the standard is recorded at the effective date, with no changes to prior periods. The adoption did not result in an impact to retained earnings. Grace elected to utilize the package of transition practical expedients provided by the standard, which among other things, permit Grace not to reassess expired or existing contracts and leases. Additionally, Grace elected to use the practical expedient provided in ASU 2018-01 “Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842,” which permits Grace to elect not to evaluate under Topic 842 existing or expired land easements not previously accounted for as leases. Prior to the adoption of Topic 842, Grace typically had not evaluated easements for lease accounting. Grace has elected not to recognize in the Consolidated Balance Sheets short-term leases, which are those with an initial term of 12 months or less. Grace has also elected not to separate lease and nonlease components. These elections apply to all asset classes. Adoption of the standard resulted in the recognition of operating lease right-of-use assets, net of accumulated amortization, of $29.4 million and operating lease liabilities of $30.0 million as of March 31, 2019 . (in millions) Amount Balance Sheet Location Operating lease right of use asset $ 29.4 Other assets Operating lease liability—current 8.7 Other current liabilities Operating lease liability—noncurrent 21.3 Other liabilities Grace leases certain real estate, office space, vehicles, railcars, and office equipment. For leases with an initial term of 12 months or less, Grace recognizes lease expense on a straight-line basis over the lease term. Finance lease costs and sublease income are not material. Many of Grace’s leases contain renewal options, which are exercisable at Grace’s discretion and may be included in lease terms when they are reasonably certain to be exercised. Grace’s lease agreements do not contain material restrictive covenants or material residual value guarantees. Where available, Grace uses the interest rate implicit in the lease to calculate the estimated present value of lease payment obligations. Where such a rate is not available, Grace uses an incremental borrowing rate based on credit-adjusted and term-specific discount rates, using a third-party yield curve. The following table presents Grace’s costs and cash flow information related to operating leases. (In millions) Three Months Ended March 31, 2019 Operating lease cost $ 3.0 Short-term and variable lease cost 3.4 Total lease cost $ 6.4 Cash payments related to operating leases $ 3.0 Right-of-use assets obtained in exchange for new operating lease liabilities 3.6 The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. March 31, Weighted average discount rate 6.8 % Weighted average remaining lease term 7.4 years The table below presents the maturities of operating lease liabilities at March 31, 2019 . (In millions) 2019 $ 8.0 2020 8.3 2021 5.4 2022 3.7 2023 2.2 Thereafter 11.2 Total undiscounted lease payments 38.8 Less: imputed interest 8.8 Present value of lease liabilities $ 30.0

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Effects of Adopting New Accounting Policies	Adoption of the standard resulted in the recognition of operating lease right-of-use assets, net of accumulated amortization, of $29.4 million and operating lease liabilities of $30.0 million as of March 31, 2019 . (in millions) Amount Balance Sheet Location Operating lease right of use asset $ 29.4 Other assets Operating lease liability—current 8.7 Other current liabilities Operating lease liability—noncurrent 21.3 Other liabilities
Lease, Cost [Table Text Block]	The following table presents Grace’s costs and cash flow information related to operating leases. (In millions) Three Months Ended March 31, 2019 Operating lease cost $ 3.0 Short-term and variable lease cost 3.4 Total lease cost $ 6.4 Cash payments related to operating leases $ 3.0 Right-of-use assets obtained in exchange for new operating lease liabilities 3.6 The following table presents the weighted average discount rate and weighted average remaining lease term related to Grace’s operating leases. March 31, Weighted average discount rate 6.8 % Weighted average remaining lease term 7.4 years
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	The table below presents the maturities of operating lease liabilities at March 31, 2019 . (In millions) 2019 $ 8.0 2020 8.3 2021 5.4 2022 3.7 2023 2.2 Thereafter 11.2 Total undiscounted lease payments 38.8 Less: imputed interest 8.8 Present value of lease liabilities $ 30.0

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 31, 2019
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories consisted of the following at March 31, 2019 , and December 31, 2018 : (In millions) March 31, December 31, Raw materials $ 66.7 $ 56.3 In process 53.6 49.1 Finished products 163.3 144.5 Other 32.6 31.2 Total inventory $ 316.2 $ 281.1

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Summary of Debt Outstanding	Components of Debt (In millions) March 31, December 31, 2018 U.S. dollar term loan, net of unamortized debt issuance costs of $8.4 (2018—$8.7) $ 936.8 $ 938.9 5.125% senior notes due 2021, net of unamortized debt issuance costs of $3.8 (2018—$4.2) 696.2 695.8 5.625% senior notes due 2024, net of unamortized debt issuance costs of $2.8 (2018—$3.0) 297.2 297.0 Debt payable to unconsolidated affiliate 47.7 48.1 Other borrowings(1) 6.2 3.5 Total debt 1,984.1 1,983.3 Less debt payable within one year 22.5 22.3 Debt payable after one year $ 1,961.6 $ 1,961.0 Weighted average interest rates on total debt 3.9 % 3.9 % ___________________________________________________________________________________________________________________
Schedule of Maturities of Long-term Debt	The principal maturities of debt outstanding at March 31, 2019 , were as follows: (In millions) 2019 $ 17.5 2020 19.5 2021 714.3 2022 17.3 2023 16.3 Thereafter 1,199.2 Total debt $ 1,984.1

Fair Value Measurements and R_2

Fair Value Measurements and Risk (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Net Investment Hedges in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents the amount of gains and losses on derivative and non-derivative instruments designated as net investment hedges, recorded to “currency translation adjustments” within “accumulated other comprehensive income (loss)” for the three months ended March 31, 2019 and 2018 . There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the periods presented. Three Months Ended March 31, (In millions) 2019 2018 Derivatives in ASC 815 net investment hedging relationships: Cross-currency swaps $ 3.8 $ (11.3 ) Non-derivatives in ASC 815 net investment hedging relationships: Foreign currency denominated debt $ — $ (4.4 ) Foreign currency denominated deferred intercompany royalties 0.1 (1.7 ) $ 0.1 $ (6.1 )
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	At March 31, 2019 , and December 31, 2018 , the carrying amounts and fair values of Grace’s debt were as follows: 3/31/2019 12/31/2018 (In millions) Carrying Amount Fair Value Carrying Amount Fair Value 2018 U.S. dollar term loan(1) $ 936.8 $ 925.1 $ 938.9 $ 914.8 5.125% senior notes due 2021(2) 696.2 718.2 695.8 697.5 5.625% senior notes due 2024(2) 297.2 315.8 297.0 301.8 Other borrowings 53.9 53.9 51.6 51.6 Total debt $ 1,984.1 $ 2,013.0 $ 1,983.3 $ 1,965.7 ___________________________________________________________________________________________________________________ (1) Carrying amounts are net of unamortized debt issuance costs and discounts of $8.4 million and $8.7 million as of March 31, 2019 and December 31, 2018 , respectively. (2) Carrying amounts are net of unamortized debt issuance costs of $3.8 million and $2.8 million as of March 31, 2019 , and $4.2 million and $3.0 million as of December 31, 2018 , related to the 5.125% senior notes due 2021 and 5.625%
Schedule of Fair Value of Assets and Liabilities Measured 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 March 31, 2019 , and December 31, 2018 : Fair Value Measurements at March 31, 2019, 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 $ 5.5 $ — $ 5.5 $ — Variable-to-fixed cross-currency swaps 0.8 — 0.8 — Total Assets $ 6.3 $ — $ 6.3 $ — Liabilities Currency derivatives $ 4.3 $ — $ 4.3 $ — Interest rate derivatives 1.9 — 1.9 — Total Liabilities $ 6.2 $ — $ 6.2 $ — Fair Value Measurements at December 31, 2018, 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 $ 3.7 $ — $ 3.7 $ — Total Assets $ 3.7 $ — $ 3.7 $ — Liabilities Currency derivatives $ 10.5 $ — $ 10.5 $ — Interest rate derivatives 0.8 — 0.8 — Variable-to-fixed cross-currency swaps 3.6 — 3.6 — Total Liabilities $ 14.9 $ — $ 14.9 $ —
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 March 31, 2019 , and December 31, 2018 : March 31, 2019 Asset Derivatives Liability Derivatives 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 assets $ (3.1 ) Interest rate contracts Other current assets — Other current liabilities 0.3 Variable-to-fixed cross-currency swaps Other current assets 14.6 Other current liabilities — Currency contracts Other assets 2.6 Other liabilities 7.4 Interest rate contracts Other assets — Other liabilities 1.6 Variable-to-fixed cross-currency swaps Other liabilities (13.8 ) Other liabilities — Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets 0.5 Other current liabilities — Currency contracts Other current liabilities (0.3 ) Other liabilities — Total derivatives $ 6.3 $ 6.2 December 31, 2018 Asset Derivatives Liability Derivatives Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments under ASC 815: Currency contracts Other current assets $ 2.4 Other current assets $ (2.9 ) Interest rate contracts Other current assets — Other current liabilities 0.1 Variable-to-fixed cross-currency swaps Other current assets — Other current assets (15.4 ) Currency contracts Other assets 1.3 Other liabilities 12.9 Interest rate contracts Other assets — Other liabilities 0.7 Variable-to-fixed cross-currency swaps Other assets — Other liabilities 19.0 Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other current assets — Other current assets (0.1 ) Currency contracts Other current assets — Other current liabilities 0.6 Total derivatives $ 3.7 $ 14.9
Schedule of Gain (Loss) on Derivative Instruments	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 three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ (1.1 ) Interest expense $ — Currency contracts(1) 1.6 Other expense 1.3 Variable-to-fixed cross-currency swaps 0.1 Interest expense 3.6 Variable-to-fixed cross-currency swaps 8.4 Other expense 8.4 Total derivatives $ 9.0 $ 13.3 Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (0.1 ) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $0.0 million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. Three Months Ended March 31, 2018 Amount of Gain (Loss) Recognized in OCI on Derivatives Location of Gain (Loss) Reclassified from Accumulated OCI into Income Amount of Gain (Loss) Reclassified from OCI into Income Derivatives in ASC 815 cash flow hedging relationships: Interest rate contracts $ 1.5 Interest expense $ (0.2 ) Currency contracts(1) (6.6 ) Other expense (6.1 ) Total derivatives $ (5.1 ) $ (6.3 ) Location of Gain (Loss) Recognized in Income on Derivatives Amount of Gain (Loss) Recognized in Income on Derivatives Derivatives not designated as hedging instruments under ASC 815: Currency contracts Other expense $ (1.4 ) ___________________________________________________________________________________________________________________ (1) Amount of gain (loss) recognized in OCI includes $(0.8) million excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI. The following table presents the total amounts of income and expense line items presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are reported. Three Months Ended March 31, 2019 2018 (In millions) 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 $ (20.0 ) $ 2.2 $ (19.3 ) $ 3.3 Gain (loss) on cash flow hedging relationships in ASC 815 Interest rate contracts Amount of gain (loss) reclassified from accumulated OCI into income $ — $ — $ (0.2 ) $ — Variable-to-fixed cross-currency swaps Amount of gain (loss) reclassified from accumulated OCI into income 3.6 8.4 — — Currency contracts Amount of gain (loss) reclassified from accumulated OCI into income — 1.3 — (6.1 ) Amount excluded from effectiveness testing recognized in earnings based on amortization approach (included in above) — 0.7 — 0.9

Pension Plans and Other Postr_2

Pension Plans and Other Postretirement Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2019
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Schedule of net funded status of fully funded, underfunded, and unfunded pension plans	The following table presents the funded status of Grace’s pension plans: (In millions) March 31, December 31, Overfunded defined benefit pension plans $ 5.9 $ 5.7 Underfunded defined benefit pension plans (67.6 ) (67.1 ) Unfunded defined benefit pension plans (362.9 ) (366.0 ) Total underfunded and unfunded defined benefit pension plans (430.5 ) (433.1 ) Pension liabilities included in other current liabilities (14.6 ) (14.7 ) Net funded status $ (439.2 ) $ (442.1 )
Components of net periodic benefit cost (income)	The following table presents the components of net periodic benefit cost (income). Three Months Ended March 31, 2019 2018 (In millions) U.S. Non-U.S. U.S. Non-U.S. Service cost $ 3.9 $ 2.2 $ 4.8 $ 2.4 Interest cost 9.6 1.3 10.3 1.3 Expected return on plan assets (12.0 ) (0.2 ) (14.5 ) (0.3 ) Amortization of prior service credit (0.2 ) — (0.2 ) — Net periodic benefit cost (income) $ 1.3 $ 3.3 $ 0.4 $ 3.4

Other Balance Sheet Accounts (T

Other Balance Sheet Accounts (Tables)	3 Months Ended
	Mar. 31, 2019
Other Balance Sheet Accounts [Abstract]
Schedule of Other Assets and Other Liabilities	(In millions) March 31, December 31, Other Current Assets Plant under construction—unconsolidated affiliate (see Note 15) $ 114.5 $ — Non-trade accounts receivable 31.4 37.9 Fair value of currency, interest rate, and commodity contracts (see Note 4) 21.2 21.4 Income taxes receivable 19.4 10.1 Other current assets 16.3 17.3 $ 202.8 $ 86.7 (In millions) March 31, December 31, Other Current Liabilities Liability to unconsolidated affiliate for plant under construction (see Note 15) $ 114.5 $ — Deferred revenue (see Note 13) 41.4 40.6 Accrued compensation 34.9 62.4 Accrued interest (see Note 3) 26.4 13.3 Environmental contingencies (see Note 8) 20.8 19.5 Income taxes payable (see Note 5) 18.0 11.3 Pension liabilities (see Note 6) 14.6 14.7 Operating lease liabilities (see Note 1) 8.7 — Liability for dam spillway replacement (see Note 8) 4.2 — Other accrued liabilities 72.5 81.7 $ 356.0 $ 243.5 Accrued compensation includes salaries and wages as well as estimated current amounts due under the annual and long-term incentive programs. (In millions) March 31, December 31, Other Liabilities Environmental contingencies (see Note 8) $ 102.6 $ 106.9 Liability for dam spillway replacement (see Note 8) 40.8 — Deferred revenue (see Note 13) 24.4 29.2 Fair value of currency and interest rate contracts (see Note 4) 22.8 32.6 Operating lease liabilities (see Note 1) 21.3 — Deferred income taxes 10.8 10.9 Asset retirement obligation 8.9 8.8 Postemployment liability 4.6 4.7 Liability to unconsolidated affiliate for plant under construction (see Note 15) — 98.8 Other noncurrent liabilities 28.3 27.9 $ 264.5 $ 319.8

Restructuring Expenses and Re_2

Restructuring Expenses and Repositioning Expenses (Tables)	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Schedule of restructuring expenses and asset impairments	The following table presents restructuring expenses by reportable segment for the three months ended March 31, 2019 and 2018 . Three Months Ended March 31, (In millions) 2019 2018 Catalysts Technologies $ 0.2 $ 0.4 Materials Technologies 1.0 0.4 Corporate (0.1 ) 0.2 Total restructuring expenses $ 1.1 $ 1.0
Schedule of restructuring liability	The following table presents components of the change in the restructuring liability from December 31, 2018 , to March 31, 2019 . (In millions) Balance, December 31, 2018 $ 10.7 Accruals for severance and other costs 1.1 Payments (3.0 ) Balance, March 31, 2019 $ 8.8

Other (Income) Expense, net (Ta

Other (Income) Expense, net (Tables)	3 Months Ended
	Mar. 31, 2019
Other Income and Expenses [Abstract]
Schedule of other (income) expense, net	Components of other (income) expense, net are as follows: Three Months Ended March 31, (In millions) 2019 2018 Defined benefit pension (income) expense other than service cost $ (1.5 ) $ (3.4 ) Third-party acquisition-related costs 0.3 0.9 Currency transaction effects (0.2 ) (0.9 ) Net (gain) loss on sales of investments and disposals of assets 0.5 0.4 Other miscellaneous (income) expense (1.3 ) (0.3 ) Total other (income) expense, net $ (2.2 ) $ (3.3 )

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
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 three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 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 $ (0.2 ) $ — $ (0.2 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.1 — 0.1 Benefit plans, net (0.1 ) — (0.1 ) Currency translation adjustments 12.9 (1.2 ) 11.7 Gain (loss) from hedging activities (4.3 ) 1.3 (3.0 ) Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ 8.5 $ 0.1 $ 8.6 Three Months Ended March 31, 2018 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 $ (0.4 ) $ 0.1 $ (0.3 ) Amortization of net deferred actuarial loss included in net periodic benefit cost 0.1 — 0.1 Benefit plans, net (0.3 ) 0.1 (0.2 ) Currency translation adjustments (20.8 ) 2.6 (18.2 ) Gain (loss) from hedging activities 2.2 (0.4 ) 1.8 Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders $ (18.9 ) $ 2.3 $ (16.6 )
Schedule of components of accumulated other comprehensive loss	The following tables present the changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2019 and 2018 : Three Months Ended March 31, 2019 Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Beginning balance $ 0.2 $ 76.2 $ (8.5 ) $ 67.9 Other comprehensive income (loss) before reclassifications — 11.7 6.6 18.3 Amounts reclassified from accumulated other comprehensive income (loss) (0.1 ) — (9.6 ) (9.7 ) Net current-period other comprehensive income (loss) (0.1 ) 11.7 (3.0 ) 8.6 Ending balance $ 0.1 $ 87.9 $ (11.5 ) $ 76.5 Three Months Ended March 31, 2018 Defined Benefit Pension and Other Postretirement Plans Currency Translation Adjustments Gain (Loss) from Hedging Activities Total Beginning balance $ 0.9 $ 41.6 $ (2.6 ) $ 39.9 Other comprehensive income (loss) before reclassifications — (18.2 ) (5.4 ) (23.6 ) Amounts reclassified from accumulated other comprehensive income (loss) (0.2 ) — 7.2 7.0 Net current-period other comprehensive income (loss) (0.2 ) (18.2 ) 1.8 (16.6 ) Ending balance $ 0.7 $ 23.4 $ (0.8 ) $ 23.3

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
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. Three Months Ended March 31, (In millions, except per share amounts) 2019 2018 Numerators Net income (loss) attributable to W. R. Grace & Co. shareholders $ 24.7 $ 43.6 Denominators Weighted average common shares—basic calculation 66.8 67.6 Dilutive effect of employee stock options 0.1 0.1 Weighted average common shares—diluted calculation 66.9 67.7 Basic earnings per share $ 0.37 $ 0.64 Diluted earnings per share $ 0.37 $ 0.64

Revenues (Tables)

Revenues (Tables)	3 Months Ended
	Mar. 31, 2019
Revenues [Abstract]
Schedule of Disaggregated of Revenue	The following tables present Grace's revenues by geography and product group, within its respective reportable segments, for the three months ended March 31, 2019 and 2018 . Three Months Ended March 31, 2019 North America Europe Middle East Africa (EMEA) Asia Pacific Latin America Total Refining Catalysts $ 72.2 $ 66.6 $ 35.7 $ 7.3 $ 181.8 Polyolefin and Chemical Catalysts 45.8 64.9 52.4 4.8 167.9 Total Catalysts Technologies 118.0 131.5 88.1 12.1 349.7 Coatings 7.0 19.7 9.4 2.1 38.2 Consumer/Pharma 9.3 19.0 4.0 4.7 37.0 Chemical process 9.0 19.9 7.7 2.3 38.9 Other 1.2 4.5 — — 5.7 Total Materials Technologies 26.5 63.1 21.1 9.1 119.8 Total Grace $ 144.5 $ 194.6 $ 109.2 $ 21.2 $ 469.5 Three Months Ended March 31, 2018 North America EMEA Asia Pacific Latin America Total Refining Catalysts $ 69.9 $ 61.3 $ 38.8 $ 13.4 $ 183.4 Polyolefin and Chemical Catalysts 32.2 58.4 38.0 3.8 132.4 Total Catalysts Technologies 102.1 119.7 76.8 17.2 315.8 Coatings 7.1 20.5 11.8 $ 2.3 $ 41.7 Consumer/Pharma 7.7 13.2 4.3 4.7 29.9 Chemical process 7.4 20.8 7.2 2.3 37.7 Other 1.7 4.5 0.1 0.1 6.4 Total Materials Technologies 23.9 59.0 23.4 9.4 115.7 Total Grace $ 126.0 $ 178.7 $ 100.2 $ 26.6 $ 431.5
Schedule of Deferred Revenues	The following table presents Grace’s deferred revenue balances as of March 31, 2019 , and December 31, 2018 : (In millions) March 31, December 31, Current $ 41.4 $ 40.6 Noncurrent 24.4 29.2 Total $ 65.8 $ 69.8
Schedule of Remaining Performance Obligations	Grace expects to recognize revenue related to remaining performance obligations over several years, as follows: Year Approximate percentage of revenue related to remaining performance obligations recognized 2019 31 % 2020 23 % 2021 20 % Thereafter through 2025 26 % 100 %

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Schedule of operating segment data	Reportable Segment Data Three Months Ended March 31, (In millions) 2019 2018 Net Sales Catalysts Technologies $ 349.7 $ 315.8 Materials Technologies 119.8 115.7 Total $ 469.5 $ 431.5 Adjusted EBIT Catalysts Technologies segment operating income $ 101.4 $ 92.1 Materials Technologies segment operating income 24.0 24.1 Corporate costs (16.2 ) (16.6 ) Certain pension costs (4.8 ) (3.8 ) Total $ 104.4 $ 95.8
Schedule of reconciliation of operating segment data to financial statements	Grace Adjusted EBIT for the three months ended March 31, 2019 and 2018 , is reconciled below to “income (loss) before income taxes” presented in the accompanying Consolidated Statements of Operations. Three Months Ended March 31, (In millions) 2019 2018 Grace Adjusted EBIT $ 104.4 $ 95.8 Costs related to legacy matters (46.9 ) (2.0 ) Restructuring and repositioning expenses (2.3 ) (5.6 ) Third-party acquisition-related costs (0.3 ) (0.9 ) Interest expense, net (19.3 ) (18.9 ) Net income (loss) attributable to noncontrolling interests (0.1 ) (0.2 ) Income (loss) before income taxes $ 35.5 $ 68.2
Schedule of geographic area data	The table below presents information related to the geographic areas in which Grace operates. Sales are attributed to geographic areas based on the location to which the product is transported. Three Months Ended March 31, (In millions) 2019 2018 Net Sales United States $ 131.6 $ 112.4 Canada 12.9 13.6 Total North America 144.5 126.0 Europe Middle East Africa 194.6 178.7 Asia Pacific 109.2 100.2 Latin America 21.2 26.6 Total $ 469.5 $ 431.5

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Summary of financial information of equity method investee	The table below presents summary financial data related to ART’s balance sheet and results of operations. (In millions) March 31, December 31, Summary Balance Sheet information: Current assets $ 307.8 $ 307.4 Noncurrent assets 177.0 160.2 Total assets $ 484.8 $ 467.6 Current liabilities $ 168.5 $ 158.3 Noncurrent liabilities 0.3 0.3 Total liabilities $ 168.8 $ 158.6 Three Months Ended March 31, (In millions) 2019 2018 Summary Statement of Operations information: Net sales $ 111.5 $ 85.2 Costs and expenses applicable to net sales 97.3 70.7 Income before income taxes 9.7 11.3 Net income 9.2 11.5
Schedule of financial data related to transactions between Grace and ART	The table below presents summary financial data related to transactions between Grace and ART. Three Months Ended March 31, (In millions) 2019 2018 Product manufactured for ART $ 66.8 $ 51.9 Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold 1.3 1.0 Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART 12.8 10.7 The table below presents balances in Grace’s Consolidated Financial Statements related to ART. (in millions) March 31, December 31, Accounts receivable $ 12.9 $ 16.2 Current asset 114.5 — Noncurrent asset — 98.8 Accounts payable 27.7 32.0 Debt payable within one year 9.8 9.8 Debt payable after one year 37.9 38.3 Current liability 114.5 — Noncurrent liability — 98.8

Basis of Presentation and Sum_4

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies - Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment$ / shares	Mar. 31, 2018USD ($)$ / shares	Dec. 31, 2018USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of reportable segments | segment	2
Depreciation and amortization	$ 24.9	$ 25
Net income (loss)	$ 24.6	$ 43.4
Net income (loss) (in dollars per shares) | $ / shares	$ 0.37	$ 0.64
Adjustment to retained earnings as a result of adoption of new accounting guidance	$ 683.3		$ 676.7
Adjustment to other liabilities as a result of adoption of new accounting guidance	(264.5)		(319.8)
Adjustment to deferred income taxes as a result of adoption of new accounting guidance	$ (525.6)		$ (529.4)

Basis of Presentation and Sum_5

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies- Effect of New Adoption (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 29.4
Operating Lease, Liability	30
Operating Lease, Liability, Current	8.7	$ 0
Operating Lease, Cost	3
Short-term and variable lease cost	3.4
Lease, Cost	6.4
Operating Lease, Payments	3
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 3.6
Operating Lease, Weighted Average Discount Rate, Percent	6.80%
Operating Lease, Weighted Average Remaining Lease Term	7 years 4 months 24 days
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 8
Lessee, Operating Lease, Liability, Payments, Due Year Two	8.3
Lessee, Operating Lease, Liability, Payments, Due Year Three	5.4
Lessee, Operating Lease, Liability, Payments, Due Year Four	3.7
Lessee, Operating Lease, Liability, Payments, Due Year Five	2.2
Lessee, Operating Lease, Liability, Payments, Due after Year Five	11.2
Lessee, Operating Lease, Liability, Payments, Due	38.8
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	$ 8.8

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 66.7	$ 56.3
In process	53.6	49.1
Finished products	163.3	144.5
Other	32.6	31.2
Total inventory	$ 316.2	$ 281.1

Debt - Components of Debt (Deta

Debt - Components of Debt (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Debt payable—unconsolidated affiliate	$ 47.7	$ 48.1
Total debt	1,984.1	1,983.3
Debt payable within one year	22.5	22.3
Debt payable after one year	$ 1,961.6	$ 1,961
Weighted average interest rates on total debt	3.90%	3.90%
2025 Term Loan
Debt Instrument [Line Items]
Total debt	$ 936.8	$ 938.9
Unamortized discount and debt issuance costs	8.4	8.7
5.125% Senior Notes, Due 2021
Debt Instrument [Line Items]
Total debt	$ 696.2	$ 695.8
Interest rate (percent)	5.125%	5.125%
Unamortized discount and debt issuance costs	$ 3.8	$ 4.2
5.625% Senior Notes, Due 2024
Debt Instrument [Line Items]
Total debt	$ 297.2	$ 297
Interest rate (percent)	5.625%	5.625%
Unamortized discount and debt issuance costs	$ 2.8	$ 3
Other borrowings
Debt Instrument [Line Items]
Total debt	$ 6.2	$ 3.5

Debt - Narrative (Details)

Debt - Narrative (Details) - Revolving Credit Facility - USD ($) $ in Millions	Mar. 31, 2019	Apr. 03, 2018
Debt Instrument [Line Items]
Senior notes issued		$ 400
Current borrowing capacity	$ 369.1

Debt - Debt Maturity Schedule (

Debt - Debt Maturity Schedule (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Maturities of Long-term Debt [Abstract]
2018	$ 17.5
2019	19.5
2020	714.3
2021	17.3
2022	16.3
Thereafter	1,199.2
Total debt	$ 1,984.1	$ 1,983.3

Fair Value Measurements and R_3

Fair Value Measurements and Risk - Carrying Amounts and Fair Values of Debt (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Document Period End Date	Mar. 31, 2019
Total debt	$ 1,984.1	$ 1,983.3
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other borrowings	53.9	51.6
Total debt	1,984.1	1,983.3
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other borrowings	53.9	51.6
Total debt	2,013	1,965.7
2025 Term Loan
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	936.8	938.9
Unamortized discount and debt issuance costs	8.4	8.7
2025 Term Loan | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	936.8	938.9
2025 Term Loan | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	925.1	914.8
5.125% Senior Notes, Due 2021
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 696.2	$ 695.8
Interest rate (percent)	5.125%	5.125%
Unamortized discount and debt issuance costs	$ 3.8	$ 4.2
5.125% Senior Notes, Due 2021 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	696.2	695.8
5.125% Senior Notes, Due 2021 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	718.2	697.5
5.625% Senior Notes, Due 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 297.2	$ 297
Interest rate (percent)	5.625%	5.625%
Unamortized discount and debt issuance costs	$ 2.8	$ 3
5.625% Senior Notes, Due 2024 | Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	297.2	297
5.625% Senior Notes, Due 2024 | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total debt	$ 315.8	$ 301.8

Fair Value Measurements and R_4

Fair Value Measurements and Risk - Narrative (Details) € in Millions	3 Months Ended
	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2019EUR (€)Currencycountry	Mar. 31, 2019USD ($)Currencycountry	Nov. 05, 2018EUR (€)	Nov. 05, 2018USD ($)	Apr. 03, 2018EUR (€)	Apr. 03, 2018USD ($)	Feb. 03, 2015USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of countries in which entity operates | country			70	70
Number of currencies used | Currency			30	30
Maturities in which forward contracts are designated as cash flow hedges or forecasted repayments of intercompany loans	36 months
Currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total contract value				$ 188,700,000
Variable-to-fixed cross-currency derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fixed interest rate							2.0231%	2.0231%
Variable-to-fixed cross-currency derivatives | 2025 Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total contract value | €					€ 525.9		€ 490.1
Amount of debt hedged						$ 600,000,000		$ 600,000,000
Fixed interest rate					1.785%	1.785%
Interest rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount of debt hedged								$ 100,000,000	$ 250,000,000
Fixed interest rate							2.775%	2.775%	2.393%
Net Investment Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred intercompany royalties designated as hedging instrument | €			€ 5.6
Amount of Gain (Loss) Reclassified from OCI into Income	$ 0	$ 0
Net Investment Hedging | Currency Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total contract value | €			€ 170
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 800,000

Fair Value Measurements and R_5

Fair Value Measurements and Risk - Financial Asset and Liabilities (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ 6.3	$ 3.7
Derivative Liability	6.2	14.9
Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	6.3	3.7
Derivative Liability	6.2	14.9
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Currency derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	5.5	3.7
Derivative Liability	4.3	10.5
Currency derivatives | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Currency derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	5.5	3.7
Derivative Liability	4.3	10.5
Currency derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0	0
Derivative Liability	0	0
Interest rate derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	1.9	0.8
Interest rate derivatives | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0	0
Interest rate derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	1.9	0.8
Interest rate derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Liability	0	0
Variable-to-fixed cross-currency derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0.8
Derivative Liability		3.6
Variable-to-fixed cross-currency derivatives | Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0
Derivative Liability		0
Variable-to-fixed cross-currency derivatives | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	0.8
Derivative Liability		3.6
Variable-to-fixed cross-currency derivatives | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset	$ 0
Derivative Liability		$ 0

Fair Value Measurements and R_6

Fair Value Measurements and Risk - Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Asset Derivatives
Total derivatives	$ 6.3	$ 3.7
Liability Derivatives
Total derivatives	6.2	14.9
Other current assets
Asset Derivatives
Total derivatives	21.2	21.4
Currency contracts | Derivatives designated as hedging instruments under ASC 815: | Other current assets
Asset Derivatives
Total derivatives	2.7	2.4
Liability Derivatives
Total derivatives	(3.1)	(2.9)
Currency contracts | Derivatives designated as hedging instruments under ASC 815: | Other assets
Asset Derivatives
Total derivatives	2.6	1.3
Currency contracts | Derivatives designated as hedging instruments under ASC 815: | Other liabilities
Liability Derivatives
Total derivatives	7.4	12.9
Currency contracts | Derivatives not designated as hedging instruments under ASC 815: | Other current assets
Asset Derivatives
Total derivatives	0.5	0
Liability Derivatives
Total derivatives		(0.1)
Currency contracts | Derivatives not designated as hedging instruments under ASC 815: | Other current liabilities
Asset Derivatives
Total derivatives	(0.3)
Liability Derivatives
Total derivatives	0	0.6
Currency contracts | Derivatives not designated as hedging instruments under ASC 815: | Other liabilities
Liability Derivatives
Total derivatives	0
Interest rate contracts | Derivatives designated as hedging instruments under ASC 815: | Other current assets
Asset Derivatives
Total derivatives	0	0
Interest rate contracts | Derivatives designated as hedging instruments under ASC 815: | Other assets
Asset Derivatives
Total derivatives	0	0
Interest rate contracts | Derivatives designated as hedging instruments under ASC 815: | Other current liabilities
Liability Derivatives
Total derivatives	0.3	0.1
Interest rate contracts | Derivatives designated as hedging instruments under ASC 815: | Other liabilities
Liability Derivatives
Total derivatives	1.6	0.7
Variable-to-fixed cross-currency derivatives | Derivatives designated as hedging instruments under ASC 815: | Other current assets
Asset Derivatives
Total derivatives	14.6	0
Liability Derivatives
Total derivatives		(15.4)
Variable-to-fixed cross-currency derivatives | Derivatives designated as hedging instruments under ASC 815: | Other assets
Asset Derivatives
Total derivatives		0
Variable-to-fixed cross-currency derivatives | Derivatives designated as hedging instruments under ASC 815: | Other current liabilities
Liability Derivatives
Total derivatives	0
Variable-to-fixed cross-currency derivatives | Derivatives designated as hedging instruments under ASC 815: | Other liabilities
Asset Derivatives
Total derivatives	(13.8)
Liability Derivatives
Total derivatives	$ 0	$ 19

Fair Value Measurements and R_7

Fair Value Measurements and Risk - Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Gains and losses on derivative instruments
Interest and Debt Expense	$ 20	$ 19.3
Nonoperating Income (Expense)	2.2	3.3
Gain (Loss) from Components Excluded from Assessment of Cash Flow Hedge Effectiveness, Net	0	(0.8)
Cash Flow Hedging
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	9	(5.1)
Amount of Gain (Loss) Reclassified from OCI into Income	13.3	(6.3)
Cash Flow Hedging | Interest rate derivatives
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	(1.1)	1.5
Cash Flow Hedging | Interest rate derivatives | Interest expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Reclassified from OCI into Income	0	(0.2)
Cash Flow Hedging | Currency contracts
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	1.6	(6.6)
Cash Flow Hedging | Currency contracts | Other expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Reclassified from OCI into Income	1.3	(6.1)
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	0.7	0.9
Cash Flow Hedging | Variable-to-fixed cross-currency derivatives | Interest expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	0.1
Amount of Gain (Loss) Reclassified from OCI into Income	3.6	0
Cash Flow Hedging | Variable-to-fixed cross-currency derivatives | Other expense
Gains and losses on derivative instruments
Amount of Gain (Loss) Recognized in OCI on Derivatives	8.4
Amount of Gain (Loss) Reclassified from OCI into Income	8.4	0
Derivatives not designated as hedging instruments under ASC 815: | Currency contracts | Other expense
Gains and losses on derivative instruments
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (0.1)	$ (1.4)

Fair Value Measurements and R_8

Fair Value Measurements and Risk - Gain (Loss) on Nonderivative Instrument (Details) - Net Investment Hedging - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	$ 0.1	$ (6.1)
Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives	3.8	(11.3)
Foreign currency denominated debt
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	0	(4.4)
Foreign currency denominated deferred intercompany royalties
Derivative Instruments, Gain (Loss) [Line Items]
Non-derivatives in ASC 815 net investment hedging relationships:	$ 0.1	$ (1.7)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Effective Income Tax Rate Reconciliation, Percent	30.70%	36.40%
Provision for (benefit from) income taxes	$ (10.9)	$ (24.8)
Effective Income Tax Rate Reconciliation, GILTI, Amount		$ 5.9
Deferred Tax Assets, Tax Credit Carryforwards, Gross of UTB	301.2
Minimum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	3
Maximum
Significant Change in Unrecognized Tax Benefits is Reasonably Possible [Line Items]
Decrease in Unrecognized Tax Benefits is Reasonably Possible	$ 5

Pension Plans and Other Postr_3

Pension Plans and Other Postretirement Benefit Plans - Pension Plans and Other Postretirement Benefit (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	$ 5.9	$ 5.7
Unfunded defined benefit pension plans	430.5	433.1
Pension liabilities included in other current liabilities	14.6	14.7
Net funded status	(439.2)	(442.1)
Underfunded Plan
Funded status of fully funded, underfunded, and unfunded pension plans:
Unfunded defined benefit pension plans	67.6	67.1
Unfunded Plan [Member]
Funded status of fully funded, underfunded, and unfunded pension plans:
Unfunded defined benefit pension plans	$ 362.9	$ 366

Pension Plans and Other Postr_4

Pension Plans and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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	$ 3.3	$ 2.8
United States
Net Periodic Benefit Cost
Service cost	3.9	4.8
Interest cost	9.6	10.3
Expected return on plan assets	(12)	(14.5)
Amortization of prior service credit	(0.2)	(0.2)
Net periodic benefit cost (income)	1.3	0.4
Non-U.S.
Net Periodic Benefit Cost
Service cost	2.2	2.4
Interest cost	1.3	1.3
Expected return on plan assets	(0.2)	(0.3)
Amortization of prior service credit	0	0
Net periodic benefit cost (income)	$ 3.3	$ 3.4

Other Balance Sheet Accounts (D

Other Balance Sheet Accounts (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Schedule of other assets and other liabilities [Line Items]
Current asset, related party	$ 114.5	$ 0
Nontrade Receivables, Current	31.4	37.9
Total Assets	6.3	3.7
Income Taxes Receivable	19.4	10.1
Other Assets, Miscellaneous, Current	16.3	17.3
Other current assets	202.8	86.7
Other Current Liabilities
Current liability, related party	114.5	0
Deferred revenue (see Note 13)	41.4	40.6
Employee-related Liabilities, Current	34.9	62.4
Accrued interest (see Note 3)	26.4	13.3
Environmental contingencies (see Note 8)	20.8	19.5
Income taxes payable (see Note 5)	18	11.3
Pension liabilities (see Note 6)	14.6	14.7
Operating Lease, Liability, Current	8.7	0
Liability for dam spillway replacement, current	4.2	0
Other accrued liabilities	72.5	81.7
Total Other Current Liabilities	356	243.5
Other Liabilities, Noncurrent
Environmental contingencies (see Note 8)	102.6	106.9
Liability for dam spillway replacement	40.8	0
Deferred revenue (see Note 13)	24.4	29.2
Derivative Liability, Noncurrent	22.8	32.6
Operating Lease, Liability, Noncurrent	21.3	0
Deferred income taxes	10.8	10.9
Asset retirement obligation	8.9	8.8
Postemployment liability	4.6	4.7
Liability to unconsolidated affiliate (see Note 15)	0	98.8
Other noncurrent liabilities	28.3	27.9
Other Liabilities, Noncurrent	264.5	319.8
Other current assets
Schedule of other assets and other liabilities [Line Items]
Total Assets	21.2	21.4
ART [Member]
Schedule of other assets and other liabilities [Line Items]
Current asset, related party	114.5	0
Other Current Liabilities
Current liability, related party	114.5	0
Other Liabilities, Noncurrent
Liability to unconsolidated affiliate (see Note 15)	$ 0	$ 98.8

Commitments and Contingent Li_2

Commitments and Contingent Liabilities (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)paymentshares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Feb. 03, 2017USD ($)	Feb. 03, 2014USD ($)
Other Commitments [Abstract]
ZAI PD account funding				$ 30	$ 34.4
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
ZAI PD Trust Balance			$ 30
Frequency of PD trust payments	6 months
Estimated annual expenses related to PD Trust	$ 0.2
Number of shares issuable under warrant (in shares) | shares	77,372,257
Legacy Matters
Accrual for Environmental Loss Contingencies	$ 123.4		126.4
Non-Vermiculite Related Matters
Legacy Matters
Accrual for Environmental Loss Contingencies	42.7		44.7
Vermiculite Related Matters
Legacy Matters
Accrual for Environmental Loss Contingencies	80.7		$ 81.7
Operable Unit 3 [Member]
Legacy Matters
Environmental Remediation Expense		$ 70
Spillway [Member]
Legacy Matters
Loss Contingency, Loss in Period	45
Minimum | Operable Unit 3 [Member]
Legacy Matters
Loss Contingency, Estimate of Possible Loss	30
Minimum | Spillway [Member]
Legacy Matters
Loss Contingency, Estimate of Possible Loss	$ 25
Site Contingency, Time Frame of Disbursements	P3Y
Maximum | Operable Unit 3 [Member]
Legacy Matters
Loss Contingency, Estimate of Possible Loss	$ 170
Maximum | Spillway [Member]
Legacy Matters
Loss Contingency, Estimate of Possible Loss	$ 80
Site Contingency, Time Frame of Disbursements	P4Y
ZAI PD Trust [Member] | Valuation Technique, Discounted Cash Flow [Member] | Minimum
Legacy Matters
Loss Contingency, Estimate of Possible Loss	$ 0
ZAI PD Trust [Member] | Valuation Technique, Discounted Cash Flow [Member] | Maximum
Legacy Matters
Loss Contingency, Estimate of Possible Loss	$ 20

Commitments and Contingent Li_3

Commitments and Contingent Liabilities - Financial Assurances (Details) $ in Millions	Mar. 31, 2019USD ($)
Financial Guarantee
Financial assurances
Gross financial assurances issued and outstanding	$ 146.1
Surety Bonds
Financial assurances
Gross financial assurances issued and outstanding	68.7
Standby Letters of Credit
Financial assurances
Gross financial assurances issued and outstanding	$ 77.4

Restructuring Expenses and Re_3

Restructuring Expenses and Repositioning Expenses - Expenses and Asset Impairments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 1.1	$ 1
Catalysts Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0.2	0.4
Materials Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	1	0.4
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ (0.1)	$ 0.2

Restructuring Expenses and Re_4

Restructuring Expenses and Repositioning Expenses - Liability Rollforward (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Restructuring Reserve [Roll Forward]
Balance, December 31, 2018	$ 10.7
Accruals for severance and other costs	1.1
Payments	(3)
Balance, March 31, 2019	$ 8.8

Restructuring Expenses and Re_5

Restructuring Expenses and Repositioning Expenses - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Repositioning expenses	$ 1.2	$ 4.6

Other (Income) Expense, net (De

Other (Income) Expense, net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other Income and Expenses [Abstract]
Defined benefit pension (income) expense other than service cost	$ (1.5)	$ (3.4)
Third-party acquisition-related costs	0.3	0.9
Currency transaction effects	(0.2)	(0.9)
Net (gain) loss on sales of investments and disposals of assets	0.5	0.4
Other miscellaneous (income) expense	(1.3)	(0.3)
Total other (income) expense, net	$ (2.2)	$ (3.3)

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) - OCI Components (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Amortization of net prior service credit included in net periodic benefit cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	$ (0.2)	$ (0.4)
Tax Benefit/ (Expense)	0	0.1
After-Tax Amount	(0.2)	(0.3)
Amortization of net deferred actuarial loss included in net periodic benefit cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	0.1	0.1
Tax Benefit/ (Expense)	0	0
After-Tax Amount	0.1	0.1
Amortization of net deferred actuarial loss included in net periodic benefit cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(0.1)	(0.3)
Tax Benefit/ (Expense)	0	0.1
After-Tax Amount	(0.1)	(0.2)
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	12.9	(20.8)
Tax Benefit/ (Expense)	(1.2)	2.6
After-Tax Amount	11.7	(18.2)
Gain (Loss) from Hedging Activities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(4.3)	2.2
Tax Benefit/ (Expense)	1.3	(0.4)
After-Tax Amount	(3)	1.8
Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	8.5	(18.9)
Tax Benefit/ (Expense)	0.1	2.3
After-Tax Amount	$ 8.6	$ (16.6)

Other Comprehensive Income (L_4

Other Comprehensive Income (Loss) - AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 337	$ 263.3
Total other comprehensive income (loss)	8.6	(16.6)
Ending balance	353.8	245.9
Defined Benefit Pension and Other Postretirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0.2	0.9
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	(0.1)	(0.2)
Total other comprehensive income (loss)	(0.1)	(0.2)
Ending balance	0.1	0.7
Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	76.2	41.6
Other comprehensive income (loss) before reclassifications	11.7	(18.2)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	11.7	(18.2)
Ending balance	87.9	23.4
Gain (Loss) from Hedging Activities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8.5)	(2.6)
Other comprehensive income (loss) before reclassifications	6.6	(5.4)
Amounts reclassified from accumulated other comprehensive income (loss)	(9.6)	7.2
Total other comprehensive income (loss)	(3)	1.8
Ending balance	(11.5)	(0.8)
Other comprehensive income (loss) attributable to W. R. Grace & Co. shareholders
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	67.9	39.9
Other comprehensive income (loss) before reclassifications	18.3	(23.6)
Amounts reclassified from accumulated other comprehensive income (loss)	(9.7)	7
Total other comprehensive income (loss)	8.6	(16.6)
Ending balance	$ 76.5	$ 23.3

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Feb. 08, 2017
Numerators
Net income (loss) attributable to W. R. Grace & Co. Shareholders	$ 24,700,000	$ 43,600,000
Denominators
Weighted average number of basic shares (in shares)	66,800,000	67,600,000
Dilutive effect of employee stock options (in shares)	100,000	100,000
Weighted average common shares—diluted calculation (in shares)	66,900,000	67,700,000
Basic earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss) (in dollars per share)	$ 0.37	$ 0.64
Diluted earnings per share attributable to W. R. Grace & Co. shareholders
Net income (loss) (in dollars per shares)	$ 0.37	$ 0.64
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive options outstanding (in shares)	900,000	1,700,000
Stock repurchase program, authorized amount			$ 250,000,000
Stock repurchased during period (in shares)	69,860	514,141
Cash paid for repurchases of common stock	$ 4,800,000	$ 35,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 134,100,000

Revenues - Narrative (Details)

Revenues - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment
Deferred Revenue Arrangement [Line Items]
Number of reportable segments | segment	2
Contract with customer, liability, revenue recognized in the period	$ 9.6
Deferred revenue, noncurrent recognition period	3 years
Remaining performance obligation	$ 113

Revenues - Disaggregation of Re

Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 469.5	$ 431.5
North America
Disaggregation of Revenue [Line Items]
Revenues	144.5	126
Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	194.6	178.7
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	109.2	100.2
Latin America
Disaggregation of Revenue [Line Items]
Revenues	21.2	26.6
Catalysts Technologies
Disaggregation of Revenue [Line Items]
Revenues	349.7	315.8
Catalysts Technologies | North America
Disaggregation of Revenue [Line Items]
Revenues	118	102.1
Catalysts Technologies | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	131.5	119.7
Catalysts Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	88.1	76.8
Catalysts Technologies | Latin America
Disaggregation of Revenue [Line Items]
Revenues	12.1	17.2
Catalysts Technologies | Refining Catalysts
Disaggregation of Revenue [Line Items]
Revenues	181.8	183.4
Catalysts Technologies | Refining Catalysts | North America
Disaggregation of Revenue [Line Items]
Revenues	72.2	69.9
Catalysts Technologies | Refining Catalysts | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	66.6	61.3
Catalysts Technologies | Refining Catalysts | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	35.7	38.8
Catalysts Technologies | Refining Catalysts | Latin America
Disaggregation of Revenue [Line Items]
Revenues	7.3	13.4
Catalysts Technologies | Polyolefin and Chemical Catalysts
Disaggregation of Revenue [Line Items]
Revenues	167.9	132.4
Catalysts Technologies | Polyolefin and Chemical Catalysts | North America
Disaggregation of Revenue [Line Items]
Revenues	45.8	32.2
Catalysts Technologies | Polyolefin and Chemical Catalysts | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	64.9	58.4
Catalysts Technologies | Polyolefin and Chemical Catalysts | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	52.4	38
Catalysts Technologies | Polyolefin and Chemical Catalysts | Latin America
Disaggregation of Revenue [Line Items]
Revenues	4.8	3.8
Materials Technologies
Disaggregation of Revenue [Line Items]
Revenues	119.8	115.7
Materials Technologies | North America
Disaggregation of Revenue [Line Items]
Revenues	26.5	23.9
Materials Technologies | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	63.1	59
Materials Technologies | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	21.1	23.4
Materials Technologies | Latin America
Disaggregation of Revenue [Line Items]
Revenues	9.1	9.4
Materials Technologies | Coatings
Disaggregation of Revenue [Line Items]
Revenues	38.2	41.7
Materials Technologies | Coatings | North America
Disaggregation of Revenue [Line Items]
Revenues	7	7.1
Materials Technologies | Coatings | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	19.7	20.5
Materials Technologies | Coatings | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	9.4	11.8
Materials Technologies | Coatings | Latin America
Disaggregation of Revenue [Line Items]
Revenues	2.1	2.3
Materials Technologies | Consumer/Pharma
Disaggregation of Revenue [Line Items]
Revenues	37	29.9
Materials Technologies | Consumer/Pharma | North America
Disaggregation of Revenue [Line Items]
Revenues	9.3	7.7
Materials Technologies | Consumer/Pharma | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	19	13.2
Materials Technologies | Consumer/Pharma | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	4	4.3
Materials Technologies | Consumer/Pharma | Latin America
Disaggregation of Revenue [Line Items]
Revenues	4.7	4.7
Materials Technologies | Chemical process
Disaggregation of Revenue [Line Items]
Revenues	38.9	37.7
Materials Technologies | Chemical process | North America
Disaggregation of Revenue [Line Items]
Revenues	9	7.4
Materials Technologies | Chemical process | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	19.9	20.8
Materials Technologies | Chemical process | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	7.7	7.2
Materials Technologies | Chemical process | Latin America
Disaggregation of Revenue [Line Items]
Revenues	2.3	2.3
Materials Technologies | Other
Disaggregation of Revenue [Line Items]
Revenues	5.7	6.4
Materials Technologies | Other | North America
Disaggregation of Revenue [Line Items]
Revenues	1.2	1.7
Materials Technologies | Other | Europe Middle East Africa (EMEA)
Disaggregation of Revenue [Line Items]
Revenues	4.5	4.5
Materials Technologies | Other | Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	0	0.1
Materials Technologies | Other | Latin America
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0.1

Revenues - Contract with Custom

Revenues - Contract with Customers (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Revenues [Abstract]
Current	$ 41.4	$ 40.6
Noncurrent	24.4	29.2
Total	$ 65.8	$ 69.8

Revenues - Remaining Performanc

Revenues - Remaining Performance Obligations (Details)	3 Months Ended
	Mar. 31, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Approximate percentage of revenue related to remaining performance obligations recognized	31.00%
Performance obligation expected timing of satisfaction, period	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Approximate percentage of revenue related to remaining performance obligations recognized	23.00%
Performance obligation expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Approximate percentage of revenue related to remaining performance obligations recognized	20.00%
Performance obligation expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Approximate percentage of revenue related to remaining performance obligations recognized	100.00%
Performance obligation expected timing of satisfaction, period	4 years

Segment Information - Reportabl

Segment Information - Reportable Segment Data (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)
Operating segment information
Number of reportable segments | segment	2
Net Sales
Revenues	$ 469.5	$ 431.5
Adjusted EBIT
Total	104.4	95.8
Reconciliation of operating segment data to financial statements
Costs related to legacy matters	46.9	2
Restructuring and repositioning expenses	(2.3)	(5.6)
Third-party acquisition-related costs	(0.3)	(0.9)
Interest expense, net	(19.3)	(18.9)
Net income (loss) attributable to noncontrolling interests	(0.1)	(0.2)
Income (loss) before income taxes	$ 35.5	68.2
Catalysts Technologies
Operating segment information
Number of reportable segments | segment	1
Number of operating segments | segment	2
Net Sales
Revenues	$ 349.7	315.8
Materials Technologies
Net Sales
Revenues	119.8	115.7
Corporate
Adjusted EBIT
Operating income	(16.2)	(16.6)
Certain pension costs	(4.8)	(3.8)
Operating Segments | Catalysts Technologies
Net Sales
Revenues	349.7	315.8
Adjusted EBIT
Operating income	101.4	92.1
Operating Segments | Materials Technologies
Net Sales
Revenues	119.8	115.7
Adjusted EBIT
Operating income	$ 24	$ 24.1

Segment Information - Geographi

Segment Information - Geographic Area Data (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Geographic Area Data
Revenues	$ 469.5	$ 431.5
United States
Geographic Area Data
Revenues	131.6	112.4
Canada
Geographic Area Data
Revenues	12.9	13.6
Total North America
Geographic Area Data
Revenues	144.5	126
Europe Middle East Africa
Geographic Area Data
Revenues	194.6	178.7
Asia Pacific
Geographic Area Data
Revenues	109.2	100.2
Latin America
Geographic Area Data
Revenues	$ 21.2	$ 26.6

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Equity method investment ownership interest (percent)	50.00%
Investment in unconsolidated affiliate	$ 159,500,000		$ 156,100,000
Equity in earnings of unconsolidated affiliate	(4,100,000)	$ (5,400,000)
ART's assets, liabilities and results of operations
Current assets	307,800,000		307,400,000
Noncurrent assets	177,000,000		160,200,000
Total assets	484,800,000		467,600,000
Current liabilities	168,500,000		158,300,000
Noncurrent liabilities	300,000		300,000
Total liabilities	168,800,000		158,600,000
Net sales	111,500,000	85,200,000
Costs and expenses applicable to net sales	97,300,000	70,700,000
Income before income taxes	9,700,000	11,300,000
Net income	9,200,000	11,500,000
Related Party Transactions [Abstract]
Product manufactured for ART	66,800,000	51,900,000
Mark-up on product manufactured for ART included as a reduction of Grace’s cost of goods sold	1,300,000	1,000,000
Charges for fixed costs; research and development; selling, general and administrative services; and depreciation to ART	$ 12,800,000	$ 10,700,000
Investment in unconsolidated affiliates
Debt Instrument, Frequency of Periodic Payment	monthly
Loan Repayment Period, Max	8 years
Document Period End Date	Mar. 31, 2019
Current asset, related party	$ 114,500,000		0
Current liability, related party	114,500,000		0
Liability to unconsolidated affiliate (see Note 15)	$ 0		98,800,000
ART [Member]
Investment in unconsolidated affiliates
Basis spread on variable rate	1.25%
Accounts receivable	$ 12,900,000		16,200,000
Noncurrent asset	0		98,800,000
Current asset, related party	114,500,000		0
Accounts payable	27,700,000		32,000,000
Debt payable within one year	9,800,000		9,800,000
Debt payable after one year	37,900,000		38,300,000
Current liability, related party	114,500,000		0
Liability to unconsolidated affiliate (see Note 15)	0		98,800,000
Grace LOC to ART [Member]
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000
Commitment fee on credit facility (as a percent)	0.10%
Joint Venture [Member]
Investment in unconsolidated affiliates
Accounts receivable	$ 3,200,000		3,700,000
Revenue from Related Parties	$ 3,200,000
Noncontrolling Interest, Ownership Percentage by Parent	87.50%
Chevron
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	$ 15,000,000
Commitment fee on credit facility (as a percent)	0.10%
Credit facility amount outstanding	$ 0		$ 0

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - Polyolefin Catalysts Business Of Albemarle Corporation - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Payments to acquire business, net of cash acquired		$ 418
Goodwill expected to be tax deductible for tax purposes	$ 140.6
Net sales	$ 25

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 540.3	$ 540.4

Acquisitions - Summary of Goodw

Acquisitions - Summary of Goodwill (Details) $ in Millions	Mar. 31, 2019USD ($)
Goodwill [Roll Forward]
Balance, December 31, 2017	$ 540.4
Balance, September 30, 2018	$ 540.3