W.R. Grace & Co. (GRA) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document and Entity Information
Entity Registrant Name	W R GRACE & CO
Entity Central Index Key	1045309
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		72,765,831
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (unaudited) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net sales	$720.60	$744.50
Cost of goods sold	462.3	475.3
Gross profit	258.3	269.2
Selling, general and administrative expenses	137.2	136.8
Research and development expenses	17.9	20.5
Interest expense and related financing costs	24.8	11.2
Interest accretion on deferred payment obligations	0.2	8.2
Chapter 11 expenses, net	1.6	6.1
Equity in earnings of unconsolidated affiliate	-6.2	-3.7
Other expense, net	1.3	10
Total costs and expenses	176.8	189.1
Income before income taxes	81.5	80.1
Provision for income taxes	-28.7	-29.8
Net income	52.8	50.3
Less: Net income attributable to noncontrolling interests	-0.1	-0.2
Net income attributable to W. R. Grace & Co. shareholders	$52.70	$50.10
Basic earnings per share:
Net income attributable to W. R. Grace & Co. shareholders	$0.72	$0.65
Weighted average number of basic shares	72.8	77
Diluted earnings per share:
Net income attributable to W. R. Grace & Co. shareholders	$0.72	$0.64
Weighted average number of diluted shares	73.5	78.1

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net income	$52.80	$50.30
Other comprehensive income (loss):
Defined benefit pension and other postretirement plans, net of income taxes	-0.4	-0.1
Currency translation adjustments	-10.8	-2.1
Gain on securities available for sale, net of income taxes	-1.9	0.7
Gain on securities available for sale, net of income taxes	0	0.1
Total other comprehensive income attributable to noncontrolling interests	-0.1	-0.1
Total other comprehensive loss	-13	-1.3
Comprehensive income	39.8	49
Less: comprehensive income attributable to noncontrolling interests	-0.2	-0.3
Comprehensive income attributable to W. R. Grace & Co. shareholders	$39.60	$48.70

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
OPERATING ACTIVITIES
Net income	$52.80	$50.30
Reconciliation to net cash used for operating activities:
Depreciation and amortization	33.5	34
Equity in earnings of unconsolidated affiliate	-6.2	-3.7
Chapter 11 expenses, net	1.6	6.1
Asbestos and bankruptcy related charges, net	-8.7	8.8
Cash paid for Chapter 11 and asbestos	491.4	1,323.90
Provision for income taxes	28.7	29.8
Cash paid for income taxes, net of refunds	-9	-16.1
Cash paid for interest on credit arrangements	-16.8	-1.6
Defined benefit pension expense	11.2	3.5
Cash paid under defined benefit pension arrangements	-4.6	-8.8
Cash paid for restructuring	-3.7	-1.9
Cash paid for repositioning	-3.1	0
Cash paid for environmental remediation	-4.2	-1.8
Changes in assets and liabilities, excluding effect of currency translation:
Trade accounts receivable	11.3	-21.1
Inventories	-2.5	-30.2
Accounts payable	19.2	13.5
All other items, net	18.3	9.8
Net cash used for operating activities	-373.6	-1,253.30
INVESTING ACTIVITIES
Capital expenditures	-40.7	-40.1
Transfer from restricted cash and cash equivalents	0	395.4
Other investing activities	0.1	-2.6
Net cash (used for) provided by investing activities	-40.6	352.7
FINANCING ACTIVITIES
Borrowings under credit arrangements	265	979.2
Repayments under credit arrangements	-24.1	-543.2
Cash paid for debt financing costs	-0.4	-23.7
Proceeds from exercise of stock options	13.7	7.7
Cash paid for repurchases of common stock	-55.6	-60.5
Other financing activities	0.2	1.3
Net cash provided by financing activities	198.8	360.8
Effect of currency exchange rate changes on cash and cash equivalents	-15.3	-2.1
Decrease in cash and cash equivalents	-230.7	-541.9
Cash and cash equivalents, beginning of period	557.5	964.8
Cash and cash equivalents, end of period	$326.80	$422.90

Consolidated_Balance_Sheets_un

Consolidated Balance Sheets (unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Current Assets
Cash and cash equivalents	$326.80	$557.50
Trade accounts receivable, less allowance of $6.1 (2014—$5.8)	447.9	481.1
Inventories	325.1	332.8
Deferred income taxes	143.7	235.4
Other current assets	95.3	84.1
Total Current Assets	1,338.80	1,690.90
Properties and equipment, net of accumulated depreciation and amortization of $1,770.1 (2014—$1,818.4)	813.1	833.5
Goodwill	443.2	452.9
Technology and other intangible assets, net	278.3	288
Deferred income taxes	682.7	612
Overfunded defined benefit pension plans	43.1	44.1
Investment in unconsolidated affiliate	106.6	113.1
Other assets	62.3	60.7
Total Assets	3,768.10	4,095.20
Current Liabilities
Debt payable within one year	88.8	96.8
Accounts payable	258.2	255.3
PI warrant liability	0	490
Other current liabilities	315.9	340
Total Current Liabilities	662.9	1,182.10
Liabilities, Noncurrent [Abstract]
Debt payable after one year	2,143.80	1,919
Deferred income taxes	17.8	19.3
Income tax contingencies	23.1	24
Underfunded and unfunded defined benefit pension plans	428.9	457.5
Other liabilities	123.4	124.3
Total Liabilities	3,399.90	3,726.20
Commitments and Contingencies—Note 8
Equity
Common stock issued, par value $0.01; 300,000,000 shares authorized; outstanding: 72,766,606 (2014—72,922,565)	0.7	0.7
Paid-in capital	498.5	526.1
Retained earnings	344.8	292.1
Treasury stock, at cost: shares: 4,680,641 (2014—4,524,688)	442.2	429.2
Accumulated other comprehensive income	-36.9	-23.8
Total W. R. Grace & Co. Shareholders' Equity	364.9	365.9
Noncontrolling interests	3.3	3.1
Total Equity	368.2	369
Total Liabilities and Equity	$3,768.10	$4,095.20

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Trade accounts receivable, allowance	$6.10	$5.80
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment and Capitalized Computer Software, Total	$1,770.10	$1,818.40
Common stock issued, par value (in dollars per share)	$0.01	$0.01
Common stock issued, shares authorized	300,000,000	300,000,000
Common stock issued, shares outstanding	72,766,606	72,922,565
Treasury stock, shares	4,680,641	4,524,688

Consolidated_Statements_of_Equ

Consolidated Statements of Equity (unaudited) (USD $)	Total	Common Stock and Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss	Noncontrolling Interests
In Millions, unless otherwise specified
Balance at Dec. 31, 2013	$571.20	$534.20	$15.80	$0	$10.60	$10.60
Increase (Decrease) in Stockholders' Equity
Net income	50.3	0	50.1	0	0	0.2
Cash paid for repurchases of common stock	-60.5	0	0	-60.5	0	0
Stock based compensation	2.8	2.8	0	0	0	0
Exercise of stock options	-7.7	-7.7	0	0	0	0
Shares issued	1.2	1.2	0	0	0	0
Other comprehensive income (loss)	-1.3	0	0	0	-1.4	0.1
Balance at Mar. 31, 2014	571.4	545.9	65.9	-60.5	9.2	10.9
Balance at Dec. 31, 2014	369	526.8	292.1	-429.2	-23.8	3.1
Increase (Decrease) in Stockholders' Equity
Net income	52.8	0	52.7	0	0	0.1
Cash paid for repurchases of common stock	-55.6	0	0	-55.6	0	0
Stock based compensation	1.3	1.3	0	0	0	0
Exercise of stock options	-13.7	-28.9	0	-42.6	0	0
Other comprehensive income (loss)	-13	0	0	0	-13.1	0.1
Balance at Mar. 31, 2015	$368.20	$499.20	$344.80	($442.20)	($36.90)	$3.30

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies	3 Months Ended
	Mar. 31, 2015
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 three operating segments: Grace Catalysts Technologies, which includes catalysts and related products and technologies used in refining, petrochemical and other chemical manufacturing applications; Grace Materials Technologies, which includes packaging technologies and engineered materials used in consumer, industrial, coatings, and pharmaceutical applications; and Grace Construction Products, which includes specialty construction chemicals and specialty building materials used in commercial, infrastructure and residential construction.
	W. R. Grace & Co. conducts all of its business through a single wholly owned subsidiary, W. R. Grace & Co.—Conn. ("Grace—Conn."). Grace—Conn. owns all of the assets, properties and rights of W. R. Grace & Co. on a consolidated basis, either directly or through subsidiaries.
	As used in these notes, the term "Company" refers to W. R. Grace & Co. The term "Grace" refers to the Company and/or one or more of its subsidiaries and, in certain cases, their respective predecessors.
	On February 5, 2015, Grace announced that the Board of Directors had approved a plan to separate Grace into two independent, publicly traded companies. The two companies, to be named prior to closing, will be "New Grace," consisting of the Catalysts Technologies and Materials Technologies business segments (excluding the packaging products product group), and “New GCP,” consisting of the Construction Products business segment and the packaging products product group. Grace intends that the separation transaction will be a tax-free spin-off to the Company's stockholders for U.S. federal income tax purposes and expects the transaction to be completed in the 2016 first quarter.
	Chapter 11 Proceedings    On April 2, 2001, Grace and 61 of its United States subsidiaries and affiliates filed voluntary petitions for reorganization under Chapter 11 of the United States Bankruptcy Code in the United States Bankruptcy Court for the District of Delaware (the "Bankruptcy Court") in order to resolve outstanding asbestos personal injury and property damage claims, including class-action lawsuits alleging damages from Zonolite® Attic Insulation ("ZAI"), a former Grace attic insulation product. In 2008, Grace and other parties filed a joint plan of reorganization with the Bankruptcy Court (as subsequently amended, the "Joint Plan"). Following the confirmation of the Joint Plan in 2011 by the Bankruptcy Court and in 2012 by a U.S. District Court, and the resolution of all appeals, Grace emerged from bankruptcy on February 3, 2014.
	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 2014 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, 2015, are not necessarily indicative of the results of operations for the year ending December 31, 2015.
	Use of Estimates    The preparation of financial statements in conformity with U.S. generally accepted accounting principles ("U.S. GAAP") requires management to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace's accounting measurements that are most affected by management's estimates of future events are:
	•	Realization values of net deferred tax assets, which depend on projections of future taxable income (see Note 5);
	•	Pension and postretirement liabilities that depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 6); and
	•	Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate resolution cost, such as litigation (see Note 8), income taxes (see Note 5), and environmental remediation (see Note 8).
	Licensing Revenue Recognition Certain customer arrangements, constituting less than 2% of our annual revenues, include licenses of technology combined with other deliverables. Generally, the licenses are non-exclusive, perpetual licenses that permit the licensee to use Grace proprietary technology to design, build, and maintain a polypropylene manufacturing plant, and to make and sell products from the plant. In these multiple-element arrangements, Grace typically bundles the license, the basic process design package, and training and consulting-type services into one fixed price contract. The fixed price contract revenue is accounted for as one unit of accounting and is recognized on a straight-line basis over the period of performance of the contract, which typically ranges from three to five years, except for contingent revenue associated with a final performance guarantee. Revenue associated with the performance guarantee is recognized when customer acceptance is obtained, which is typically at the time that the licensee’s plant is operational. Elements in the fixed price contract are not accounted for as separate units of accounting because they do not have standalone value. Each of the deliverables are necessary components to the successful construction and future operation of the manufacturing plants, and the elements have interdependencies such that there is minimal value in each deliverable without the other bundled elements. Other services and optional software that are sold in connection with license arrangements qualify as separate units of accounting, with revenue recognized when services are rendered and in the case of process control software, when installed and functional. Additional services that are not part of the fixed price contract are billed on a variable basis. The selling prices of the significant deliverables described above are based on Grace’s best estimate of selling price, determined using historical business information.
	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.
	Effect of New Accounting Standards    In April 2014, the FASB issued ASU 2014-08 "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity." This update is intended to change the requirements for reporting discontinued operations and enhance convergence of the FASB’s and the International Accounting Standard Board’s ("IASB") reporting requirements for discontinued operations. The new requirements are effective for fiscal years beginning on or after December 15, 2014, and for interim periods within those fiscal years, with early adoption permitted. Grace adopted this standard in the first quarter and it did not have a material effect on the Consolidated Financial Statements.
	In May 2014, the FASB issued ASU 2014-09 "Revenue from Contracts with Customers." This update is intended to remove inconsistencies and weaknesses in revenue requirements; provide a more robust framework for addressing revenue issues; improve comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets; provide more useful information to users of financial statements through improved disclosure requirements; and simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. The new requirements are effective for fiscal years beginning after December 15, 2016, and for interim periods within those fiscal years, with early adoption not permitted. Grace is currently evaluating its effect on the Consolidated Financial Statements and will adopt this standard when it becomes applicable.
	In April 2015, the FASB issued ASU 2015-03 "Simplifying the Presentation of Debt Issuance Costs." This update is part of the FASB's Simplification Initiative and is also intended to enhance convergence with the IASB's treatment of debt issuance costs. The update requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new requirements are effective for fiscal years beginning after December 15, 2015, and for interim periods within those fiscal years, with early adoption permitted. Grace is currently evaluating its effect on the Consolidated Financial Statements and the timing of adoption.

Inventories

Inventories	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories are stated at the lower of cost or market, and cost is determined using FIFO. Inventories consisted of the following at March 31, 2015, and December 31, 2014:
	(In millions)	March 31,		December 31,
		2015		2014
	Raw materials	$	84.6	$	78.8
	In process	47.1		47.2
	Finished products	166.4		177.7
	Other	27		29.1
		$	325.1	$	332.8

Debt

Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Debt	Components of Debt
	(In millions)	March 31,			December 31,
		2015			2014
	U.S. dollar term loan, net of unamortized discount of $2.0 at March 31, 2015, and $2.1 at December 31, 2014(1)	$	940.4		$	692.6
	5.125% senior notes due 2021	700			700
	5.625% senior notes due 2024	300			300
	Euro term loan, net of unamortized discount of $0.4 at March 31, 2015, and $0.4 at December 31, 2014(2)	160.8			181.2
	Debt payable—unconsolidated affiliate	31.2			31.5
	Deferred payment obligation	28.4			28.2
	Other borrowings(3)	71.8			82.3
	Total debt	2,232.60			2,015.80
	Less debt payable within one year	88.8			96.8
	Debt payable after one year	$	2,143.80		$	1,919.00
	Weighted average interest rates on total debt	4.1		%	4.3		%
	___________________________________________________________________________________________________________________
	-1	Interest at LIBOR +200 bps with a 75 bps LIBOR floor at March 31, 2015, and LIBOR +225 bps with a 75 bps LIBOR floor at December 31, 2014
	-2	Interest at EURIBOR +225 bps with a 75 bps EURIBOR floor at March 31, 2015, and EURIBOR +250 bps with a 75 bps EURIBOR floor at December 31, 2014
	-3	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.
	The principal maturities of debt outstanding at March 31, 2015, were as follows:
		(In millions)
	2015	$	87.3
	2016	16.8
	2017	44.3
	2018	15.5
	2019	14.8
	Thereafter	2,053.90
	Total debt	$	2,232.60
	On January 30, 2015, Grace borrowed on its $250 million delayed draw term loan facility and used the funds, together with cash on hand, to repurchase the warrant issued to the PI Trust for $490 million. (See Note 8 for Chapter 11 information.)
	Grace has reviewed the impact of the planned separation of Grace into "New Grace" and "New GCP" on the credit agreement entered into upon emergence from bankruptcy (the "Credit Agreement"). Grace anticipates that the Credit Agreement will remain with "New Grace" but at the time of the separation will require an amendment to permit the separation. Grace intends to seek such amendment as well as repay a substantial amount of the borrowings under the Credit Agreement in connection with the separation. If an amendment is not granted, Grace will be required to repay all term loan and revolver debt and enter into a new borrowing facility.
	Grace has reviewed the senior notes for the impact of the separation of Grace into "New Grace" and "New GCP." The senior notes will remain with "New Grace" and Grace does not believe that the separation will have any impact on payment or other terms.

Fair_Value_Measurements_and_Ri

Fair Value Measurements and Risk	3 Months Ended
	Mar. 31, 2015
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 as discussed in Note 3. 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, 2015, the carrying amounts and fair values of Grace's debt were as follows:
		31-Mar-15								31-Dec-14
	(In millions)	Carrying Amount				Fair Value				Carrying Amount		Fair Value
	U.S. dollar term loan(1)	$	940.4			$	943.6			$	692.6	$	691.3
	5.125% senior notes due 2021	700				733.3				700		720.9
	5.625% senior notes due 2024	300				321				300		312
	Euro term loan(1)	160.8				161.4				181.2		181.4
	Other borrowings	131.4				131.4				142		142
	Total debt	$	2,232.60			$	2,290.70			$	2,015.80	$	2,047.60
	___________________________________________________________________________________________________________________
	-1	Carrying amounts are net of unamortized discounts of $2.0 million and $0.4 million as of March 31, 2015, and $2.1 million and $0.4 million as of December 31, 2014, related to the U.S. dollar term loan and euro term loan, respectively.
	At March 31, 2015, 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.
	Commodity Derivatives
	From time to time, Grace enters into commodity derivatives such as fixed-rate swaps or options with financial institutions to mitigate the risk of volatility of prices of natural gas or other commodities. Under fixed-rate swaps, Grace locks in a fixed rate with a financial institution for future purchases, purchases its commodity from a supplier at the prevailing market rate, and then settles with the bank for any difference in the rates, thereby "swapping" a variable rate for a fixed rate.
	The valuation of Grace's fixed-rate natural gas swaps was determined using a market approach, based on natural gas futures trading prices quoted on the New York Mercantile Exchange. Commodity fixed-rate swaps with maturities of not more than 12 months are used and designated as cash flow hedges of forecasted purchases of natural gas. Current open contracts hedge forecasted transactions until December 2015. The effective portion of the gain or loss on the commodity contracts is recorded in "accumulated other comprehensive income" and reclassified into income in the same period or periods that the underlying commodity purchase affects income. At March 31, 2015, the contract volume, or notional amount, of the commodity contracts was 3.7 million MMBtu (million British thermal units) with a total contract value of $12.9 million.
	The valuation of Grace's natural gas call options was determined using a market approach, based on the strike price of the options and the natural gas futures trading prices quoted on the New York Mercantile Exchange. Commodity option contracts with maturities of not more than 24 months are used and designated as cash flow hedges of forecasted purchases of natural gas. Current open option contracts hedge forecasted transactions until June 2015. The effective portion of the gain or loss on the commodity contracts is recorded in "accumulated other comprehensive income" and reclassified into income in the same period or periods that the underlying purchases affect income. At March 31, 2015, the contract volume, or notional amount, of the commodity option contracts was 0.2 million MMBtu and the natural gas futures trading price of option contracts was less than the strike price.
	The valuation of Grace's fixed-rate aluminum swaps was determined using a market approach, based on aluminum futures trading prices quoted on the London Metal Exchange. Commodity fixed-rate swaps with maturities of not more than 12 months are used and designated as cash flow hedges of forecasted purchases of aluminum. Current open contracts hedge forecasted transactions until February 2016. The effective portion of the gain or loss on the commodity contracts is recorded in "accumulated other comprehensive income" and reclassified into income in the same period or periods that the underlying commodity purchase affects income. At March 31, 2015, the contract volume, or notional amount, of the commodity contracts was 1.4 million pounds with a total contract value of $1.2 million.
	Currency Derivatives
	Because Grace operates in over 40 countries and does business in more than 50 currencies, results are exposed to fluctuations in currency exchange rates. Grace seeks to minimize exposure to these fluctuations by matching sales in volatile currencies with expenditures in the same currencies, but it is not always possible to do so. From time to time Grace will use financial instruments such as currency forward contracts, options, or combinations of the two 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.
	The valuation of Grace's currency exchange rate forward contracts is determined using both a market approach and an income approach. Inputs used to value currency exchange rate forward contracts consist of: (1) spot rates, which are quoted by various financial institutions; (2) forward points, which are primarily affected by changes in interest rates; and (3) discount rates used to present value future cash flows, which are based on the London Interbank Offered Rate (LIBOR) curve or overnight indexed swap rates.
	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" and reclassified into "interest expense and related financing costs" during the hedged interest period.
	In connection with its emergence financing, Grace entered into an interest rate swap beginning on February 3, 2015, and maturing on February 3, 2020, fixing the LIBOR component of the interest on $250 million of Grace's term debt at a rate of 2.393%. The valuation of this interest rate swap is determined using both a market approach and an income approach, using prevailing market interest rates and discount rates to present value future cash flows based on the forward LIBOR yield curves.
	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, 2015, and December 31, 2014:
		Fair Value Measurements at March 31, 2015, Using
	(In millions)	Total				Quoted Prices in Active Markets for Identical Assets or Liabilities				Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 1)				(Level 2)		(Level 3)
	Assets
	Currency derivatives	$	9.8			$	—			$	9.8	$	—
	Total Assets	$	9.8			$	—			$	9.8	$	—
	Liabilities
	Currency derivatives	$	0.4			$	—			$	0.4	$	—
	Interest rate derivatives	9				—				9		—
	Commodity derivatives	2.7				—				2.7		—
	Total Liabilities	$	12.1			$	—			$	12.1	$	—
		Fair Value Measurements at December 31, 2014, Using
	(In millions)	Total				Quoted Prices in Active Markets for Identical Assets or Liabilities				Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 1)				(Level 2)		(Level 3)
	Assets
	Currency derivatives	$	3.3			$	—			$	3.3	$	—
	Total Assets	$	3.3			$	—			$	3.3	$	—
	Liabilities
	Currency derivatives	$	0.1			$	—			$	0.1	$	—
	Interest rate derivatives	5.5				—				5.5		—
	Commodity derivatives	2.6				—				2.6		—
	Total Liabilities	$	8.2			$	—			$	8.2	$	—
	The following tables present the location and fair values of derivative instruments included in the Consolidated Balance Sheets as of March 31, 2015, and December 31, 2014:
	31-Mar-15	Asset Derivatives						Liability Derivatives
	(In millions)	Balance Sheet		Fair Value				Balance Sheet		Fair Value
		Location						Location
	Derivatives designated as hedging instruments under ASC 815:
	Commodity contracts	Other current assets		$	—			Other current liabilities		$	2.7
	Currency contracts	Other current assets		6.5				Other current liabilities		—
	Interest rate contracts	Other current assets		—				Other current liabilities		3.9
	Currency contracts	Other assets		3.1				Other liabilities		—
	Interest rate contracts	Other assets		—				Other liabilities		5.1
	Derivatives not designated as hedging instruments under ASC 815:
	Currency contracts	Other current assets		0.2				Other current liabilities		0.4
	Total derivatives			$	9.8					$	12.1
	December 31, 2014	Asset Derivatives						Liability Derivatives
(In millions)	Balance Sheet		Fair Value				Balance Sheet		Fair Value
	Location						Location
Derivatives designated as hedging instruments under ASC 815:
Commodity contracts	Other current assets		$	—			Other current liabilities		$	2.6
Currency contracts	Other current assets		0.8				Other current liabilities		—
Interest rate contracts	Other current assets		—				Other current liabilities		2.5
Currency contracts	Other assets		0.9				Other liabilities		—
Interest rate contracts	Other assets		—				Other liabilities		3
Derivatives not designated as hedging instruments under ASC 815:
Currency contracts	Other current assets		1.6				Other current liabilities		0.1
Total derivatives			$	3.3					$	8.2
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, 2015 and 2014:
Three Months Ended March 31, 2015	Amount of Gain (Loss) Recognized in OCI on Derivatives				Location of Gain (Loss) Reclassified from Accumulated OCI into Income		Amount of Gain (Loss) Reclassified from OCI into Income
(In millions)	(Effective Portion)				(Effective Portion)		(Effective Portion)
Derivatives in ASC 815 cash flow hedging relationships:
Interest rate contracts	$	(3.5	)		Interest expense		$	(0.6	)
Currency contracts	6.4				Other expense		6.5
Currency contracts	0.1				Cost of goods sold		—
Commodity contracts	(1.0		)		Cost of goods sold		(1.0		)
Total derivatives	$	2					$	4.9
					Location of Gain (Loss) Recognized in Income on Derivatives		Amount of Gain (Loss) Recognized in Income on Derivatives
Derivatives not designated as hedging instruments under ASC 815:
Currency contracts					Other expense		$	(0.5	)
Three Months Ended March 31, 2014	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
(In millions)	(Effective Portion)				(Effective Portion)		(Effective Portion)
Derivatives in ASC 815 cash flow hedging relationships:
Interest rate contracts	$	1			Interest expense		$	—
Currency contracts	0.5				Other expense		0.5
Commodity contracts	0.4				Cost of goods sold		0.3
Total derivatives	$	1.9					$	0.8
					Location of Gain (Loss) Recognized in Income on Derivatives		Amount of Gain (Loss) Recognized in Income on Derivatives
Derivatives not designated as hedging instruments under ASC 815:
Currency contracts					Other expense		$	4.5
Net Investment Hedges
Grace uses foreign currency denominated debt as nonderivative hedging instruments in certain net investment hedges. The effective portion of gains and losses attributable to these net investment hedges is recorded to "currency translation adjustments" within "accumulated other comprehensive income." 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. During 2014, Grace designated its €148.5 million term loan principal as a hedging instrument of its net investment in European subsidiaries.
The following table presents the location and amount of gains and losses on nonderivative instruments designated as net investment hedges as of March 31, 2015; there were no net investment hedges as of March 31, 2014. There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the period presented in the table below.
Three Months Ended March 31, 2015	Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments				Location of Gain (Loss) Reclassified from Accumulated OCI into Income		Amount of Gain (Loss) Reclassified from Accumulated OCI into Income
(In millions)	(Effective Portion)				(Ineffective Portion)		(Ineffective Portion)
Nonderivatives in ASC 815 net investment hedging relationships:
Foreign currency denominated debt	$	20			Not applicable		$	—
Total nonderivatives	$	20					$	—
Credit Risk
Grace is exposed to credit risk in its trade accounts receivable. Customers in the petroleum refining and construction industries represent the greatest exposure. Grace's credit evaluation policies, relatively short collection terms and history of minimal credit losses mitigate credit risk exposures. Grace does not generally require collateral for its trade accounts receivable, but may require a bank letter of credit in certain instances, particularly when selling to customers in cash-restricted countries.
Grace may also be exposed to credit risk in its derivatives contracts. Grace monitors counterparty credit risk and currently does not anticipate nonperformance by counterparties to its derivatives. Grace's derivative contracts are with internationally recognized commercial financial institutions.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	The annualized effective tax rate on 2015 forecasted income is estimated to be 35.0% as of March 31, 2015, compared with 17.1% for the year ended December 31, 2014. The increase in the rate compared with the prior year primarily relates to a 2014 benefit for the release of reserves related to uncertain tax positions.
	Grace generated approximately $1,300 million in U.S. federal tax deductions in 2014 relating to its emergence from bankruptcy, including approximately $670 million relating to payments made upon emergence and $632 million upon payment of the PI deferred payment obligation, as well as $490 million in U.S. federal tax deductions in February 2015 upon repurchase of the warrant held by the PI Trust. These items, a significant portion of which were previously recorded as deferred tax assets for temporary differences, will be available to reduce U.S. federal taxable income in 2015 and future years. Grace also expects to generate U.S. federal tax deductions of $30 million upon payment of the ZAI PD deferred payment obligation in 2017. The present value of the expected settlement amount has already been recorded as a deferred tax asset for temporary differences. Grace expects to carryforward U.S. federal NOLs generated during 2014 and 2015. Under U.S. federal income tax law, a corporation is generally permitted to carryforward NOLs for a 20-year period for deduction against future taxable income. (See Note 8 for Chapter 11 information.)
	The following table summarizes the balance of deferred tax assets, net of deferred tax liabilities, at March 31, 2015, of $807.0 million:
		Deferred Tax Asset		Valuation Allowance			Net Deferred Tax Asset
		(Net of Liabilities)(2)
	United States—Federal(1)	$	717.1	$	(2.4	)	$	714.7
	United States—States(1)	61.4		(5.9		)	55.5
	Germany	35.5		—			35.5
	Other Foreign	5.5		(4.2		)	1.3
	Total	$	819.5	$	(12.5	)	$	807
	___________________________________________________________________________________________________________________
	-1	The U.S. federal deductions generated during 2014 relating to emergence of $670 million and settlement of the PI deferred payment obligation of $632 million, and the $490 million warrant repurchase on February 3, 2015, plus the $30 million ZAI PD deferred payment obligation, account for a significant portion of the U.S. federal and state deferred tax assets.
	-2	Deferred tax assets are net of $5.7 million of income tax contingencies related to these deferred tax assets.
	Grace will need to generate approximately $2,000 million of U.S. federal taxable income by 2035 (or approximately $100 million per year during the carryforward period) to fully realize the U.S. federal and a majority of the U.S. state net deferred tax assets.
	The following table summarizes expiration dates in jurisdictions where we have, or will have, material tax loss carryforwards:
		Expiration Dates
	United States—Federal	2034 - 2035
	United States—States	2015 - 2035
	Brazil	Unlimited Carryforward
	In evaluating Grace's ability to realize its deferred tax assets, Grace considers all reasonably available positive and negative evidence, including recent earnings experience, expectations of future taxable income and the tax character of that income, the period of time over which the temporary differences become deductible and the carryforward and/or carryback periods available to Grace for tax reporting purposes in the related jurisdiction. In estimating future taxable income, Grace relies upon assumptions and estimates about future activities, including the amount of future federal, state and international pretax operating income that Grace will generate; the reversal of temporary differences; and the implementation of feasible and prudent tax planning strategies. Grace records a valuation allowance to reduce deferred tax assets to the amount that it believes is more likely than not to be realized.
	Grace believes it is reasonably possible that in the next 12 months the amount of the liability for unrecognized tax benefits could decrease by approximately $3 million.

Pension_Plans_and_Other_Postre

Pension Plans and Other Postretirement Benefit Plans	3 Months Ended
	Mar. 31, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Pension Plans and Other Postretirement Benefit Plans	Pension Plans    The following table presents the funded status of Grace's fully-funded, underfunded, and unfunded pension plans:
	(In millions)	March 31,			December 31,
		2015			2014
	Overfunded defined benefit pension plans	$	43.1		$	44.1
	Underfunded defined benefit pension plans	(79.7		)	(79.5		)
	Unfunded defined benefit pension plans	(349.2		)	(378.0		)
	Total underfunded and unfunded defined benefit pension plans	(428.9		)	(457.5		)
	Pension liabilities included in other current liabilities	(14.8		)	(15.6		)
	Net funded status	$	(400.6	)	$	(429.0	)
	Fully-funded plans include several advance-funded plans where the fair value of the plan assets exceeds the projected benefit obligation ("PBO"). This group of plans was overfunded by $43.1 million as of March 31, 2015, and the overfunded status is reflected as "overfunded defined benefit pension plans" in the Consolidated Balance Sheets. 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 combined balance of the underfunded and unfunded plans was $443.7 million as of March 31, 2015.
	Postretirement Benefits Other Than Pensions    Grace has provided postretirement health care and life insurance benefits for retired employees of certain U.S. business units and certain divested business units. The postretirement medical plan provided various levels of benefits to employees hired before 1993 who retired from Grace after age 55 with at least 10 years of service. These plans are unfunded and Grace pays a portion of the costs of benefits under these plans as they are incurred. Grace applies ASC 715 to these plans, which requires that the future costs of postretirement health care and life insurance benefits be accrued over the employees' years of service. Actuarial gains and losses are recognized in the Consolidated Balance Sheets as a component of Shareholders' Equity, with amortization of the net actuarial gains and losses that exceed 10 percent of the accumulated postretirement benefit obligation recognized each quarter in the Consolidated Statements of Operations over the average future service period of active employees.
	In June 2014, Grace announced that it would discontinue its postretirement medical plan for all U.S. employees effective October 31, 2014, and eliminate certain postretirement life insurance benefits. As a result of these actions, Grace recognized a gain of $41.9 million in other comprehensive income in the 2014 second quarter. Grace amortized $39.5 million from accumulated other comprehensive income into the Consolidated Statement of Operations during the five-month period from June to October 2014.
	Components of Net Periodic Benefit Cost (Income)
		Three Months Ended March 31,
		2015									2014
		Pension						Other Post			Pension						Other Post
	(In millions)	U.S.			Non-U.S.			Retirement			U.S.			Non-U.S.			Retirement
	Service cost	$	6.4		$	3		$	—		$	5.9		$	2.7		$	—
	Interest cost	13.8			4.2			0.1			15.2			5.7			0.6
	Expected return on plan assets	(17.6		)	(3.4		)	—			(17.5		)	(3.9		)	—
	Amortization of prior service cost (credit)	0.1			—			(1.0		)	0.2			—			(0.1		)
	Amortization of net deferred actuarial loss (gain)	—			—			0.2			—			—			(0.2		)
	Mark-to-market adjustment	—			—			—			(3.1		)	—			—
	Net periodic benefit cost (income)	$	2.7		$	3.8		$	(0.7	)	$	0.7		$	4.5		$	0.3
	At emergence, benefit payments of approximately $27 million were paid from a U.S. nonqualified pension plan in connection with Grace's emergence from bankruptcy. As a result, that plan was remeasured as of March 1, 2014, using a discount rate of 4.43%. The remeasurement resulted in a mark-to-market gain of $3.1 million.
	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 and trustee 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 costs related to this benefit plan for the three months ended March 31, 2015, were $4.1 million compared with $3.3 million for the prior-year quarter.

Other_Balance_Sheet_Accounts

Other Balance Sheet Accounts	3 Months Ended
	Mar. 31, 2015
Other Balance Sheet Accounts [Abstract]
Other Balance Sheet Accounts
	(In millions)	March 31,		December 31,
		2015		2014
	Other Current Liabilities
	Accrued compensation	$	67.7	$	77
	Income tax payable	34.8		34.1
	Accrued interest	25.5		21
	Customer volume rebates	24.9		37.8
	Deferred revenue	19.3		19.4
	Pension liabilities	14.8		15.6
	Environmental contingencies	14		21.5
	Deferred tax liability	1.6		1.5
	Other accrued liabilities	113.3		112.1
		$	315.9	$	340
	Accrued compensation in the table above includes salaries and wages as well as estimated current amounts due under the annual and long-term incentive programs.

Commitments_and_Contingent_Lia

Commitments and Contingent Liabilities	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingent Liabilities	Asbestos-Related 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.
	Following the repurchase of the warrant issued to the PI Trust in connection with emergence from bankruptcy, Grace has satisfied all of its financial obligations to the PI Trust.
	Grace has fixed and contingent obligations remaining to the PD Trust. With respect to property damage claims related to Grace’s former attic insulation product installed in the U.S. ("ZAI PD Claims"), the PD Trust was funded with $34.4 million on the Effective Date. Grace is obligated to make a payment of $30 million to the PD Trust in respect of ZAI PD Claims on February 3, 2017, and has recorded a liability of $28.4 million representing the present value of this amount in "debt payable after one year" in the accompanying Consolidated Balance Sheets. Grace is also obligated to make up to 10 contingent deferred payments of $8 million per year to the PD Trust in respect of ZAI PD Claims during the 20-year period beginning on the fifth anniversary of the Effective Date, with each such payment due only if the assets of the PD Trust in respect of ZAI PD Claims fall below $10 million during the preceding year. Grace has not accrued for the 10 additional payments since Grace does not currently believe they are probable. Grace is not obligated to make additional payments to the PD Trust in respect of ZAI PD Claims beyond the payments described above. Grace has satisfied all of its financial obligations with respect to Canadian ZAI PD Claims.
	With respect to other asbestos property damage claims ("Other PD Claims"), claims unresolved as of the Effective Date are to be litigated in the bankruptcy court and any future claims are to be litigated in a federal district court, in each case pursuant to procedures to be 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"). 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. As of March 31, 2015, Grace has accrued $0.4 million since the Effective Date related to two Other PD Claims that were filed in the bankruptcy but were not resolved until after the Effective Date.
	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.
	Environmental Remediation    Grace is subject to loss contingencies resulting from extensive and evolving federal, state, local and foreign environmental laws and regulations relating to the generation, storage, handling, discharge, disposition and stewardship of hazardous wastes and other materials. Grace accrues for anticipated costs associated with 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 whenever circumstances become better defined or response efforts and their costs can be better estimated. These liabilities are evaluated based on currently available information, including the progress of remedial investigation at each site, the current status of discussions with regulatory authorities regarding the method and extent of remediation at each site, existing technology, prior experience in contaminated site remediation and the apportionment of costs among potentially responsible parties.
	Estimated Investigation and Remediation Costs
	At March 31, 2015, Grace's estimated liability for environmental investigation and remediation costs totaled $54.2 million, compared with $61.7 million at December 31, 2014, and was included in "other current liabilities" and "other liabilities" in the Consolidated Balance Sheets. These amounts are based on funding and/or remediation agreements in place and Grace's estimate of costs for sites not subject to a formal remediation plan for which sufficient information is available to estimate response costs. These amounts do not include certain response costs for the Libby vermiculite mine area or certain vermiculite expansion facilities, which may be material but are not currently estimable. Due to these vermiculite-related matters, it is probable that Grace's actual response costs will exceed Grace's current estimates by material amounts. Net cash paid against previously established reserves for the three months ended March 31, 2015 and 2014, were $4.2 million and $1.8 million, respectively.
	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. The U.S. Environmental Protection Agency (the "EPA") and Grace are engaged in a remedial investigation of the Libby mine and the surrounding area.
	During 2010, the EPA began reinvestigating certain facilities on a list of 105 facilities where vermiculite concentrate from the Libby mine may have been used, stored or processed. Grace is cooperating with the EPA on this reinvestigation and has remediated several of these facilities. It is probable that the EPA will request additional remediation at other facilities.
	Grace's total estimated liability for response costs that are currently estimable related to its former vermiculite operations in Libby and vermiculite processing sites outside of Libby at March 31, 2015, and December 31, 2014, was $13.4 million and $19.4 million, respectively, excluding interest where applicable. It is probable that Grace's ultimate liability for these vermiculite-related matters will exceed current estimates by material amounts. Grace's current recorded liability will be adjusted as Grace receives new information and amounts become reasonably estimable.
	Non-Vermiculite-Related Matters
	At March 31, 2015, and December 31, 2014, Grace's estimated liability for response costs at sites not related to its former vermiculite mining and processing activities was $40.8 million and $42.3 million, respectively. This liability relates to Grace's current and former operations, including its share of liability for off-site disposal at facilities where it has been identified as a potentially responsible party. 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.
	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, asphalt, amines 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. Both the liability and annual expense related to product warranties are immaterial to the Consolidated Financial Statements.
	•	Performance guarantees offered to customers under certain licensing arrangements. Grace has not established a liability for these arrangements based on past performance.
	•	Licenses of intellectual property by Grace to third parties in which Grace has agreed to indemnify the licensee against third party infringement claims.
	•	Contracts providing for the sale of a former business unit or product line in which Grace has agreed to indemnify the buyer against liabilities arising prior to the closing of the transaction, including environmental liabilities.
	•	Guarantees of real property lease obligations of third parties, typically arising out of (a) leases entered into by former subsidiaries of Grace, or (b) the assignment or sublease of a lease by Grace to a third party.
	Financial Assurances    Financial assurances have been established for a variety of purposes, including insurance and environmental matters, trade-related commitments and other matters. At March 31, 2015, Grace had gross financial assurances issued and outstanding of $134.4 million, composed of $34.2 million of surety bonds issued by various insurance companies and $100.2 million of standby letters of credit and other financial assurances issued by various banks.
	Accounting for Contingencies    Although the outcome of each of the matters discussed above cannot be predicted with certainty, Grace has assessed its risk and has made accounting estimates as required under U.S. GAAP.

Restructuring_Expenses_and_Ass

Restructuring Expenses and Asset Impairments	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring Expenses and Asset Impairments	In the first quarter, Grace incurred costs from restructuring actions as a result of changes in the business environment and its business structure, which are included in "other expense, net" in the Consolidated Statements of Operations. Grace incurred $9.5 million ($2.6 million in Catalysts Technologies, $2.3 million in Construction Products, $0.6 million in Materials Technologies, and $4.0 million in Corporate) of restructuring expenses during the first quarter, compared with $0.7 million during the prior-year quarter. These costs are not included in segment operating income. Substantially all costs related to the restructuring programs are expected to be paid by December 31, 2015.
	Restructuring Expenses	Three Months Ended March 31,
	(In millions)	2015			2014
	Restructuring expenses	$	9.5		$	0.7
	Total restructuring expenses	$	9.5		$	0.7
	Restructuring Liability	Total
	(In millions)
	Balance, December 31, 2014	$	4.5
	Accruals for severance and other costs	9.5
	Payments	(3.7		)
	Currency translation adjustments and other	0.1
	Balance, March 31, 2015	$	10.4

Other_Income_Expense_net

Other (Income) Expense, net	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
Other (Income) Expense, net	Components of other expense, net are as follows:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Restructuring expenses	$	9.5		$	0.7
	Asbestos and bankruptcy-related charges, net	(8.7		)	8.8
	Repositioning expenses	6.9			—
	Provision for environmental remediation, net	(3.3		)	1.2
	Currency transaction effects	(2.8		)	0.3
	Net loss on sales of investments and disposals of assets	0.4			0.7
	Interest income	(0.1		)	(0.5		)
	Other miscellaneous income	(0.6		)	(1.2		)
	Total other expense, net	$	1.3		$	10
	In the first quarter, Grace finalized its accounting for emergence from bankruptcy and recorded a gain of $9.0 million reflecting the final resolution of bankruptcy liabilities.

Other_Comprehensive_Income

Other Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Other Comprehensive Income	The following tables present the pre-tax, tax, and after-tax components of Grace's other comprehensive loss for the three months ended March 31, 2015 and 2014:
	Three Months Ended March 31, 2015	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
	(In millions)
	Defined benefit pension and other postretirement plans:
	Amortization of net prior service credit included in net periodic benefit cost	$	(0.9	)	$	0.4		$	(0.5	)
	Amortization of net deferred actuarial loss included in net periodic benefit cost	0.2			(0.1		)	0.1
	Benefit plans, net	(0.7		)	0.3			(0.4		)
	Currency translation adjustments	(10.8		)	—			(10.8		)
	Loss from hedging activities	(2.9		)	1			(1.9		)
	Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(14.4	)	$	1.3		$	(13.1	)
	Three Months Ended March 31, 2014	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
	(In millions)
	Defined benefit pension and other postretirement plans:
	Amortization of net prior service cost included in net periodic benefit cost	$	0.1		$	—		$	0.1
	Amortization of net deferred actuarial gain included in net periodic benefit cost	(0.2		)	—			(0.2		)
	Benefit plans, net	(0.1		)	—			(0.1		)
	Currency translation adjustments	(2.1		)	—			(2.1		)
	Gain from hedging activities	1.1			(0.4		)	0.7
	Gain on securities available for sale	0.1			—			0.1
	Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(1.0	)	$	(0.4	)	$	(1.4	)
	The following tables present the changes in accumulated other comprehensive income (loss), net of tax, for the three months ended March 31, 2015 and 2014:
	Three Months Ended March 31, 2015	Defined Benefit Pension and Other Postretirement Plans			Currency Translation Adjustments			Gain (Loss) from Hedging Activities			Total
	(In millions)
	Beginning balance	$	4		$	(22.8	)	$	(5.0	)	$	(23.8	)
	Other comprehensive income (loss) before reclassifications	—			(10.8		)	2.3			(8.5		)
	Amounts reclassified from accumulated other comprehensive income	(0.4		)	—			(4.2		)	(4.6		)
	Net current-period other comprehensive loss	(0.4		)	(10.8		)	(1.9		)	(13.1		)
	Ending balance	$	3.6		$	(33.6	)	$	(6.9	)	$	(36.9	)
	Three Months Ended March 31, 2014	Defined Benefit Pension and Other Postretirement Plans			Currency Translation Adjustments			Gain (Loss) from Hedging Activities			Unrealized Loss on Investment			Gain on Securities Available for Sale		Total
	(In millions)
	Beginning balance	$	6.6		$	5.2		$	(0.5	)	$	(0.8	)	$	0.1	$	10.6
	Other comprehensive income (loss) before reclassifications	—			(2.1		)	1.2			—			0.1		(0.8		)
	Amounts reclassified from accumulated other comprehensive income	(0.1		)	—			(0.5		)	—			—		(0.6		)
	Net current-period other comprehensive income (loss)	(0.1		)	(2.1		)	0.7			—			0.1		(1.4		)
	Ending balance	$	6.5		$	3.1		$	0.2		$	(0.8	)	$	0.2	$	9.2
	Grace is a global enterprise operating in over 40 countries with local currency generally deemed to be the functional currency for accounting purposes. The currency translation amount represents the adjustments necessary to translate the balance sheets valued in local currencies to the U.S. dollar as of the end of each period presented, and to translate revenues and expenses at average exchange rates for each period presented.
	See Note 4 for a discussion of hedging activities. See Note 6 for a discussion of pension plans and other postretirement benefit plans.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
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)	2015		2014
	Numerators
	Net income attributable to W. R. Grace & Co. shareholders	$	52.7	$	50.1
	Denominators
	Weighted average common shares—basic calculation	72.8		77
	Dilutive effect of employee stock options	0.7		1.1
	Weighted average common shares—diluted calculation	73.5		78.1
	Basic earnings per share	$	0.72	$	0.65
	Diluted earnings per share	$	0.72	$	0.64
	There were approximately 0.2 million anti-dilutive options outstanding for the three months ended March 31, 2015.
	On February 4, 2014, Grace announced that the Grace Board of Directors had authorized a share repurchase program of up to $500 million expected to be completed over the following 12 to 24 months at the discretion of management. Grace completed this initial share repurchase program on January 15, 2015. On February 5, 2015, Grace announced that its Board of Directors has authorized an additional share repurchase program of up to $500 million. The timing of the repurchases and the actual amount repurchased will depend on a variety of factors, including the market price of Grace's shares, the strategic deployment of capital, and general market and economic conditions. During the three months ended March 31, 2015, Grace repurchased 581,204 shares of Company common stock for $55.6 million pursuant to the terms of its share repurchase programs.

Operating_Segment_Information

Operating Segment Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Operating Segment Information	Grace is a global producer of specialty chemicals and specialty materials. Grace manages its business through three operating segments: Grace Catalysts Technologies, Grace Materials Technologies, and Grace Construction Products. Grace Catalysts Technologies includes catalysts and related products and technologies used in refining, petrochemical and other chemical manufacturing applications. Grace's Advanced Refining Technologies (ART) joint venture is managed in this segment. ART is an unconsolidated affiliate, and Grace accounts for ART using the equity method as discussed in Note 14. Grace Materials Technologies includes packaging products and engineered materials, coatings and sealants used in consumer, industrial, and pharmaceutical applications. Grace Construction Products includes specialty construction chemicals and specialty building materials used in commercial, infrastructure and residential construction. Intersegment sales are eliminated in consolidation. The table below presents information related to Grace's operating segments. Only those corporate expenses directly related to the operating 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 operating segment performance as defined benefit pension expense is not managed at an operating segment level.
	Grace defines Adjusted EBIT (a non-GAAP financial measure) to be net income adjusted for interest income and expense; income taxes; costs related to Chapter 11 and asbestos; restructuring and repositioning expenses and asset impairments; pension costs other than service and interest costs, expected returns on plan assets, and amortization of prior service costs/credits; income and expense items related to divested businesses, product lines, and certain other investments; gains and losses on sales of businesses, product lines, and certain other investments; and certain other unusual or infrequent items that are not representative of underlying trends.
	Operating Segment Data
		Three Months Ended March 31,
	(In millions)	2015			2014
	Net Sales
	Catalysts Technologies	$	281		$	284.5
	Materials Technologies	200.3			219.8
	Construction Products	239.3			240.2
	Total	$	720.6		$	744.5
	Adjusted EBIT
	Catalysts Technologies segment operating income	$	73.7		$	71.2
	Materials Technologies segment operating income	41			45.5
	Construction Products segment operating income	29.4			25.4
	Corporate costs	(20.6		)	(22.5		)
	Certain pension costs	(6.5		)	(8.3		)
	Total	$	117		$	111.3
	Corporate costs include corporate support function costs and other corporate costs such as professional fees and insurance premiums.
	Grace Adjusted EBIT for the three months ended March 31, 2015 and 2014, is reconciled below to income before income taxes presented in the accompanying Consolidated Statements of Operations.
	Reconciliation of Operating Segment Data to Financial Statements
		Three Months Ended March 31,
	(In millions)	2015			2014
	Grace Adjusted EBIT	$	117		$	111.3
	Benefit (costs) related to Chapter 11 and asbestos, net	9.7			(15.5		)
	Pension MTM adjustment and other related costs, net	(4.7		)	4.8
	Restructuring expenses	(9.5		)	(0.7		)
	Repositioning expenses	(6.9		)	—
	Income and expense items related to divested businesses	0.7			(1.1		)
	Interest expense, net	(24.9		)	(18.9		)
	Net income attributable to noncontrolling interests	0.1			0.2
	Income before income taxes	$	81.5		$	80.1
	The table below presents information related to the geographic areas in which Grace operates. Sales are attributed to geographic areas based on customer location.
	Geographic Area Data
		Three Months Ended March 31,
	(In millions)	2015			2014
	Net Sales
	United States	$	214.6		$	206
	Canada and Puerto Rico	17.8			16.6
	Total North America	232.4			222.6
	Europe Middle East Africa	235.2			274.9
	Asia Pacific	176.6			164.9
	Latin America	76.4			82.1
	Total	$	720.6		$	744.5

Unconsolidated_Affiliate

Unconsolidated Affiliate	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Unconsolidated Affiliate	Grace accounts for its 50% ownership interest in ART using the equity method of accounting. Grace's investment in ART amounted to $106.6 million and $113.1 million as of March 31, 2015, and December 31, 2014, respectively, and the amount included in "equity in earnings of unconsolidated affiliate" in the accompanying Consolidated Statements of Operations totaled $6.2 million for the three months ended March 31, 2015, compared with $3.7 million for the three months ended March 31, 2014, respectively.
	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. The table below presents summary financial data related to transactions between Grace and ART.
		Three Months Ended March 31,
	(In millions)	2015		2014
	Grace sales of catalysts to ART	$	54.2	$	65.5
	Charges for fixed costs, research and development and selling, general and administrative services to ART	5.9		7.5
	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 expire on February 26, 2016. No amounts were outstanding at March 31, 2015, and December 31, 2014.

Summary_of_Significant_Account

Summary of Significant Accounting and Financial Reporting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
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 amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the Consolidated Financial Statements, and the reported amounts of revenues and expenses for the periods presented. Actual amounts could differ from those estimates, and the differences could be material. Changes in estimates are recorded in the period identified. Grace's accounting measurements that are most affected by management's estimates of future events are:
	•	Realization values of net deferred tax assets, which depend on projections of future taxable income (see Note 5);
	•	Pension and postretirement liabilities that depend on assumptions regarding participant life spans, future inflation, discount rates and total returns on invested funds (see Note 6); and
	•	Contingent liabilities, which depend on an assessment of the probability of loss and an estimate of ultimate resolution cost, such as litigation (see Note 8), income taxes (see Note 5), and environmental remediation (see Note 8).
New Accounting Standards, Policy	Effect of New Accounting Standards    In April 2014, the FASB issued ASU 2014-08 "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity." This update is intended to change the requirements for reporting discontinued operations and enhance convergence of the FASB’s and the International Accounting Standard Board’s ("IASB") reporting requirements for discontinued operations. The new requirements are effective for fiscal years beginning on or after December 15, 2014, and for interim periods within those fiscal years, with early adoption permitted. Grace adopted this standard in the first quarter and it did not have a material effect on the Consolidated Financial Statements.
	In May 2014, the FASB issued ASU 2014-09 "Revenue from Contracts with Customers." This update is intended to remove inconsistencies and weaknesses in revenue requirements; provide a more robust framework for addressing revenue issues; improve comparability of revenue recognition practices across entities, industries, jurisdictions and capital markets; provide more useful information to users of financial statements through improved disclosure requirements; and simplify the preparation of financial statements by reducing the number of requirements to which an entity must refer. The new requirements are effective for fiscal years beginning after December 15, 2016, and for interim periods within those fiscal years, with early adoption not permitted. Grace is currently evaluating its effect on the Consolidated Financial Statements and will adopt this standard when it becomes applicable.
	In April 2015, the FASB issued ASU 2015-03 "Simplifying the Presentation of Debt Issuance Costs." This update is part of the FASB's Simplification Initiative and is also intended to enhance convergence with the IASB's treatment of debt issuance costs. The update requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The new requirements are effective for fiscal years beginning after December 15, 2015, and for interim periods within those fiscal years, with early adoption permitted. Grace is currently evaluating its effect on the Consolidated Financial Statements and the timing of adoption.

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories consisted of the following at March 31, 2015, and December 31, 2014:
	(In millions)	March 31,		December 31,
		2015		2014
	Raw materials	$	84.6	$	78.8
	In process	47.1		47.2
	Finished products	166.4		177.7
	Other	27		29.1
		$	325.1	$	332.8

Debt_Tables

Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt [Table Text Block]	The principal maturities of debt outstanding at March 31, 2015, were as follows:
		(In millions)
	2015	$	87.3
	2016	16.8
	2017	44.3
	2018	15.5
	2019	14.8
	Thereafter	2,053.90
	Total debt	$	2,232.60
Disclosure of debt	Components of Debt
	(In millions)	March 31,			December 31,
		2015			2014
	U.S. dollar term loan, net of unamortized discount of $2.0 at March 31, 2015, and $2.1 at December 31, 2014(1)	$	940.4		$	692.6
	5.125% senior notes due 2021	700			700
	5.625% senior notes due 2024	300			300
	Euro term loan, net of unamortized discount of $0.4 at March 31, 2015, and $0.4 at December 31, 2014(2)	160.8			181.2
	Debt payable—unconsolidated affiliate	31.2			31.5
	Deferred payment obligation	28.4			28.2
	Other borrowings(3)	71.8			82.3
	Total debt	2,232.60			2,015.80
	Less debt payable within one year	88.8			96.8
	Debt payable after one year	$	2,143.80		$	1,919.00
	Weighted average interest rates on total debt	4.1		%	4.3		%
	___________________________________________________________________________________________________________________
	-1	Interest at LIBOR +200 bps with a 75 bps LIBOR floor at March 31, 2015, and LIBOR +225 bps with a 75 bps LIBOR floor at December 31, 2014
	-2	Interest at EURIBOR +225 bps with a 75 bps EURIBOR floor at March 31, 2015, and EURIBOR +250 bps with a 75 bps EURIBOR floor at December 31, 2014
	-3	Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries.

Fair_Value_Measurements_and_Ri1

Fair Value Measurements and Risk (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	At March 31, 2015, the carrying amounts and fair values of Grace's debt were as follows:
		31-Mar-15								31-Dec-14
	(In millions)	Carrying Amount				Fair Value				Carrying Amount		Fair Value
	U.S. dollar term loan(1)	$	940.4			$	943.6			$	692.6	$	691.3
	5.125% senior notes due 2021	700				733.3				700		720.9
	5.625% senior notes due 2024	300				321				300		312
	Euro term loan(1)	160.8				161.4				181.2		181.4
	Other borrowings	131.4				131.4				142		142
	Total debt	$	2,232.60			$	2,290.70			$	2,015.80	$	2,047.60
	___________________________________________________________________________________________________________________
	-1	Carrying amounts are net of unamortized discounts of $2.0 million and $0.4 million as of March 31, 2015, and $2.1 million and $0.4 million as of December 31, 2014, related to the U.S. dollar term loan and euro term loan, respectively.
Schedule of assets and liabilities measured at fair value on a recurring basis	The following tables present the fair value hierarchy for financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2015, and December 31, 2014:
		Fair Value Measurements at March 31, 2015, Using
	(In millions)	Total				Quoted Prices in Active Markets for Identical Assets or Liabilities				Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 1)				(Level 2)		(Level 3)
	Assets
	Currency derivatives	$	9.8			$	—			$	9.8	$	—
	Total Assets	$	9.8			$	—			$	9.8	$	—
	Liabilities
	Currency derivatives	$	0.4			$	—			$	0.4	$	—
	Interest rate derivatives	9				—				9		—
	Commodity derivatives	2.7				—				2.7		—
	Total Liabilities	$	12.1			$	—			$	12.1	$	—
		Fair Value Measurements at December 31, 2014, Using
	(In millions)	Total				Quoted Prices in Active Markets for Identical Assets or Liabilities				Significant Other Observable Inputs		Significant Unobservable Inputs
						(Level 1)				(Level 2)		(Level 3)
	Assets
	Currency derivatives	$	3.3			$	—			$	3.3	$	—
	Total Assets	$	3.3			$	—			$	3.3	$	—
	Liabilities
	Currency derivatives	$	0.1			$	—			$	0.1	$	—
	Interest rate derivatives	5.5				—				5.5		—
	Commodity derivatives	2.6				—				2.6		—
	Total Liabilities	$	8.2			$	—			$	8.2	$	—
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, 2015, and December 31, 2014:
	31-Mar-15	Asset Derivatives						Liability Derivatives
	(In millions)	Balance Sheet		Fair Value				Balance Sheet		Fair Value
		Location						Location
	Derivatives designated as hedging instruments under ASC 815:
	Commodity contracts	Other current assets		$	—			Other current liabilities		$	2.7
	Currency contracts	Other current assets		6.5				Other current liabilities		—
	Interest rate contracts	Other current assets		—				Other current liabilities		3.9
	Currency contracts	Other assets		3.1				Other liabilities		—
	Interest rate contracts	Other assets		—				Other liabilities		5.1
	Derivatives not designated as hedging instruments under ASC 815:
	Currency contracts	Other current assets		0.2				Other current liabilities		0.4
	Total derivatives			$	9.8					$	12.1
	December 31, 2014	Asset Derivatives						Liability Derivatives
	(In millions)	Balance Sheet		Fair Value				Balance Sheet		Fair Value
		Location						Location
	Derivatives designated as hedging instruments under ASC 815:
	Commodity contracts	Other current assets		$	—			Other current liabilities		$	2.6
	Currency contracts	Other current assets		0.8				Other current liabilities		—
	Interest rate contracts	Other current assets		—				Other current liabilities		2.5
	Currency contracts	Other assets		0.9				Other liabilities		—
	Interest rate contracts	Other assets		—				Other liabilities		3
	Derivatives not designated as hedging instruments under ASC 815:
	Currency contracts	Other current assets		1.6				Other current liabilities		0.1
	Total derivatives			$	3.3					$	8.2
Schedule of the location and amount of gains and losses on derivative instruments included in the Consolidated Statements of Operations, or initially recognized in other comprehensive income (loss) ("OCI"), when applicable	The following tables present the location and amount of gains and losses on derivative instruments included in the Consolidated Statements of Operations or, when applicable, gains and losses initially recognized in other comprehensive income (loss) ("OCI") for the three months ended March 31, 2015 and 2014:
	Three Months Ended March 31, 2015	Amount of Gain (Loss) Recognized in OCI on Derivatives				Location of Gain (Loss) Reclassified from Accumulated OCI into Income		Amount of Gain (Loss) Reclassified from OCI into Income
	(In millions)	(Effective Portion)				(Effective Portion)		(Effective Portion)
	Derivatives in ASC 815 cash flow hedging relationships:
	Interest rate contracts	$	(3.5	)		Interest expense		$	(0.6	)
	Currency contracts	6.4				Other expense		6.5
	Currency contracts	0.1				Cost of goods sold		—
	Commodity contracts	(1.0		)		Cost of goods sold		(1.0		)
	Total derivatives	$	2					$	4.9
						Location of Gain (Loss) Recognized in Income on Derivatives		Amount of Gain (Loss) Recognized in Income on Derivatives
	Derivatives not designated as hedging instruments under ASC 815:
	Currency contracts					Other expense		$	(0.5	)
	Three Months Ended March 31, 2014	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
	(In millions)	(Effective Portion)				(Effective Portion)		(Effective Portion)
	Derivatives in ASC 815 cash flow hedging relationships:
	Interest rate contracts	$	1			Interest expense		$	—
	Currency contracts	0.5				Other expense		0.5
	Commodity contracts	0.4				Cost of goods sold		0.3
	Total derivatives	$	1.9					$	0.8
						Location of Gain (Loss) Recognized in Income on Derivatives		Amount of Gain (Loss) Recognized in Income on Derivatives
	Derivatives not designated as hedging instruments under ASC 815:
	Currency contracts					Other expense		$	4.5
Nonderivative Instruments, Gain (Loss) [Table Text Block]	The following table presents the location and amount of gains and losses on nonderivative instruments designated as net investment hedges as of March 31, 2015; there were no net investment hedges as of March 31, 2014. There were no reclassifications of the effective portion of net investment hedges out of OCI and into earnings for the period presented in the table below.
	Three Months Ended March 31, 2015	Amount of Gain (Loss) Recognized in OCI in Currency Translation Adjustments				Location of Gain (Loss) Reclassified from Accumulated OCI into Income		Amount of Gain (Loss) Reclassified from Accumulated OCI into Income
	(In millions)	(Effective Portion)				(Ineffective Portion)		(Ineffective Portion)
	Nonderivatives in ASC 815 net investment hedging relationships:
	Foreign currency denominated debt	$	20			Not applicable		$	—
	Total nonderivatives	$	20					$	—

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The following table summarizes the balance of deferred tax assets, net of deferred tax liabilities, at March 31, 2015, of $807.0 million:
		Deferred Tax Asset		Valuation Allowance			Net Deferred Tax Asset
		(Net of Liabilities)(2)
	United States—Federal(1)	$	717.1	$	(2.4	)	$	714.7
	United States—States(1)	61.4		(5.9		)	55.5
	Germany	35.5		—			35.5
	Other Foreign	5.5		(4.2		)	1.3
	Total	$	819.5	$	(12.5	)	$	807
	___________________________________________________________________________________________________________________
	-1	The U.S. federal deductions generated during 2014 relating to emergence of $670 million and settlement of the PI deferred payment obligation of $632 million, and the $490 million warrant repurchase on February 3, 2015, plus the $30 million ZAI PD deferred payment obligation, account for a significant portion of the U.S. federal and state deferred tax assets.
	-2	Deferred tax assets are net of $5.7 million of income tax contingencies related to these deferred tax assets.
Summary of Operating Loss Carryforwards [Table Text Block]	The following table summarizes expiration dates in jurisdictions where we have, or will have, material tax loss carryforwards:
		Expiration Dates
	United States—Federal	2034 - 2035
	United States—States	2015 - 2035
	Brazil	Unlimited Carryforward

Pension_Plans_and_Other_Postre1

Pension Plans and Other Postretirement Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Net funded status of fully funded, underfunded, and unfunded pension plans	Pension Plans    The following table presents the funded status of Grace's fully-funded, underfunded, and unfunded pension plans:
	(In millions)	March 31,			December 31,
		2015			2014
	Overfunded defined benefit pension plans	$	43.1		$	44.1
	Underfunded defined benefit pension plans	(79.7		)	(79.5		)
	Unfunded defined benefit pension plans	(349.2		)	(378.0		)
	Total underfunded and unfunded defined benefit pension plans	(428.9		)	(457.5		)
	Pension liabilities included in other current liabilities	(14.8		)	(15.6		)
	Net funded status	$	(400.6	)	$	(429.0	)
Components of net periodic benefit cost (income)	Components of Net Periodic Benefit Cost (Income)
		Three Months Ended March 31,
		2015									2014
		Pension						Other Post			Pension						Other Post
	(In millions)	U.S.			Non-U.S.			Retirement			U.S.			Non-U.S.			Retirement
	Service cost	$	6.4		$	3		$	—		$	5.9		$	2.7		$	—
	Interest cost	13.8			4.2			0.1			15.2			5.7			0.6
	Expected return on plan assets	(17.6		)	(3.4		)	—			(17.5		)	(3.9		)	—
	Amortization of prior service cost (credit)	0.1			—			(1.0		)	0.2			—			(0.1		)
	Amortization of net deferred actuarial loss (gain)	—			—			0.2			—			—			(0.2		)
	Mark-to-market adjustment	—			—			—			(3.1		)	—			—
	Net periodic benefit cost (income)	$	2.7		$	3.8		$	(0.7	)	$	0.7		$	4.5		$	0.3

Other_Balance_Sheet_Accounts_T

Other Balance Sheet Accounts (Tables)	3 Months Ended
	Mar. 31, 2015
Other Balance Sheet Accounts [Abstract]
Schedule of Other Assets and Other Liabilities [Table Text Block]
	(In millions)	March 31,		December 31,
		2015		2014
	Other Current Liabilities
	Accrued compensation	$	67.7	$	77
	Income tax payable	34.8		34.1
	Accrued interest	25.5		21
	Customer volume rebates	24.9		37.8
	Deferred revenue	19.3		19.4
	Pension liabilities	14.8		15.6
	Environmental contingencies	14		21.5
	Deferred tax liability	1.6		1.5
	Other accrued liabilities	113.3		112.1
		$	315.9	$	340

Restructuring_Expenses_and_Ass1

Restructuring Expenses and Asset Impairments (Tables)	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Schedule of restructuring expenses and asset impairments
	Restructuring Expenses	Three Months Ended March 31,
	(In millions)	2015			2014
	Restructuring expenses	$	9.5		$	0.7
	Total restructuring expenses	$	9.5		$	0.7
Schedule of restructuring liability
	Restructuring Liability	Total
	(In millions)
	Balance, December 31, 2014	$	4.5
	Accruals for severance and other costs	9.5
	Payments	(3.7		)
	Currency translation adjustments and other	0.1
	Balance, March 31, 2015	$	10.4

Other_Income_Expense_net_Table

Other (Income) Expense, net (Tables)	3 Months Ended
	Mar. 31, 2015
Other Income and Expenses [Abstract]
Schedule of other (income) expense, net	Components of other expense, net are as follows:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Restructuring expenses	$	9.5		$	0.7
	Asbestos and bankruptcy-related charges, net	(8.7		)	8.8
	Repositioning expenses	6.9			—
	Provision for environmental remediation, net	(3.3		)	1.2
	Currency transaction effects	(2.8		)	0.3
	Net loss on sales of investments and disposals of assets	0.4			0.7
	Interest income	(0.1		)	(0.5		)
	Other miscellaneous income	(0.6		)	(1.2		)
	Total other expense, net	$	1.3		$	10

Other_Comprehensive_Income_Tab

Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Tabular disclosure of pre-tax, tax, and after-tax components of other comprehensive income (loss)	The following tables present the pre-tax, tax, and after-tax components of Grace's other comprehensive loss for the three months ended March 31, 2015 and 2014:
	Three Months Ended March 31, 2015	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
	(In millions)
	Defined benefit pension and other postretirement plans:
	Amortization of net prior service credit included in net periodic benefit cost	$	(0.9	)	$	0.4		$	(0.5	)
	Amortization of net deferred actuarial loss included in net periodic benefit cost	0.2			(0.1		)	0.1
	Benefit plans, net	(0.7		)	0.3			(0.4		)
	Currency translation adjustments	(10.8		)	—			(10.8		)
	Loss from hedging activities	(2.9		)	1			(1.9		)
	Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(14.4	)	$	1.3		$	(13.1	)
	Three Months Ended March 31, 2014	Pre-Tax Amount			Tax Benefit/ (Expense)			After-Tax Amount
	(In millions)
	Defined benefit pension and other postretirement plans:
	Amortization of net prior service cost included in net periodic benefit cost	$	0.1		$	—		$	0.1
	Amortization of net deferred actuarial gain included in net periodic benefit cost	(0.2		)	—			(0.2		)
	Benefit plans, net	(0.1		)	—			(0.1		)
	Currency translation adjustments	(2.1		)	—			(2.1		)
	Gain from hedging activities	1.1			(0.4		)	0.7
	Gain on securities available for sale	0.1			—			0.1
	Other comprehensive loss attributable to W. R. Grace & Co. shareholders	$	(1.0	)	$	(0.4	)	$	(1.4	)
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, 2015 and 2014:
	Three Months Ended March 31, 2015	Defined Benefit Pension and Other Postretirement Plans			Currency Translation Adjustments			Gain (Loss) from Hedging Activities			Total
	(In millions)
	Beginning balance	$	4		$	(22.8	)	$	(5.0	)	$	(23.8	)
	Other comprehensive income (loss) before reclassifications	—			(10.8		)	2.3			(8.5		)
	Amounts reclassified from accumulated other comprehensive income	(0.4		)	—			(4.2		)	(4.6		)
	Net current-period other comprehensive loss	(0.4		)	(10.8		)	(1.9		)	(13.1		)
	Ending balance	$	3.6		$	(33.6	)	$	(6.9	)	$	(36.9	)
	Three Months Ended March 31, 2014	Defined Benefit Pension and Other Postretirement Plans			Currency Translation Adjustments			Gain (Loss) from Hedging Activities			Unrealized Loss on Investment			Gain on Securities Available for Sale		Total
	(In millions)
	Beginning balance	$	6.6		$	5.2		$	(0.5	)	$	(0.8	)	$	0.1	$	10.6
	Other comprehensive income (loss) before reclassifications	—			(2.1		)	1.2			—			0.1		(0.8		)
	Amounts reclassified from accumulated other comprehensive income	(0.1		)	—			(0.5		)	—			—		(0.6		)
	Net current-period other comprehensive income (loss)	(0.1		)	(2.1		)	0.7			—			0.1		(1.4		)
	Ending balance	$	6.5		$	3.1		$	0.2		$	(0.8	)	$	0.2	$	9.2

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
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)	2015		2014
	Numerators
	Net income attributable to W. R. Grace & Co. shareholders	$	52.7	$	50.1
	Denominators
	Weighted average common shares—basic calculation	72.8		77
	Dilutive effect of employee stock options	0.7		1.1
	Weighted average common shares—diluted calculation	73.5		78.1
	Basic earnings per share	$	0.72	$	0.65
	Diluted earnings per share	$	0.72	$	0.64

Operating_Segment_Information_

Operating Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule of operating segment data	Operating Segment Data
		Three Months Ended March 31,
	(In millions)	2015			2014
	Net Sales
	Catalysts Technologies	$	281		$	284.5
	Materials Technologies	200.3			219.8
	Construction Products	239.3			240.2
	Total	$	720.6		$	744.5
	Adjusted EBIT
	Catalysts Technologies segment operating income	$	73.7		$	71.2
	Materials Technologies segment operating income	41			45.5
	Construction Products segment operating income	29.4			25.4
	Corporate costs	(20.6		)	(22.5		)
	Certain pension costs	(6.5		)	(8.3		)
	Total	$	117		$	111.3
Schedule of reconciliation of operating segment data to financial statements	Reconciliation of Operating Segment Data to Financial Statements
		Three Months Ended March 31,
	(In millions)	2015			2014
	Grace Adjusted EBIT	$	117		$	111.3
	Benefit (costs) related to Chapter 11 and asbestos, net	9.7			(15.5		)
	Pension MTM adjustment and other related costs, net	(4.7		)	4.8
	Restructuring expenses	(9.5		)	(0.7		)
	Repositioning expenses	(6.9		)	—
	Income and expense items related to divested businesses	0.7			(1.1		)
	Interest expense, net	(24.9		)	(18.9		)
	Net income attributable to noncontrolling interests	0.1			0.2
	Income before income taxes	$	81.5		$	80.1
Schedule of geographic area data	Geographic Area Data
		Three Months Ended March 31,
	(In millions)	2015			2014
	Net Sales
	United States	$	214.6		$	206
	Canada and Puerto Rico	17.8			16.6
	Total North America	232.4			222.6
	Europe Middle East Africa	235.2			274.9
	Asia Pacific	176.6			164.9
	Latin America	76.4			82.1
	Total	$	720.6		$	744.5

Unconsolidated_Affiliate_Table

Unconsolidated Affiliate (Tables)	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
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)	2015		2014
	Grace sales of catalysts to ART	$	54.2	$	65.5
	Charges for fixed costs, research and development and selling, general and administrative services to ART	5.9		7.5

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting and Financial Reporting Policies (Details)	3 Months Ended
	Mar. 31, 2015	Apr. 02, 2001
	segment	entity
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	3
Spin transaction, expected period to complete	2016
Number of United States subsidiaries and affiliates filed voluntary petitions for reorganization		61
Licensing Revenue, Percent of Total Revenue	2.00%

Inventories_Details

Inventories (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]
Raw materials	$84.60	$78.80
In process	47.1	47.2
Finished products	166.4	177.7
Other	27	29.1
Total inventories	$325.10	$332.80

Debt_Details

Debt (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Debt, Long-term and Short-term, Combined Amount	$2,232.60	$2,015.80
Debt payable—unconsolidated affiliate	31.2	31.5
Deferred payment obligation	28.4	28.2
Less debt payable within one year	-88.8	-96.8
Debt payable after one year	2,143.80	1,919
Weighted average interest rates on total debt	4.10%	4.30%
Maturities of Long-term Debt [Abstract]
Long-term Debt, Current Maturities	87.3
Long-term Debt, Maturing in Year Two	16.8
Long-term Debt, Maturing in Year Three	44.3
Long-term Debt, Maturing in Year Four	15.5
Long-term Debt, Maturing in Year Five	14.8
Long-term Debt, Maturing Thereafter	2,053.90
Senior Secured Credit Facility to Fund Emergence	250
Payments for Repurchase of Warrants	490
Term Loan B (USD) [Member]
Debt Instrument, Basis Spread on Variable Rate	2.00%	2.25%
Debt Instrument, Unamortized Discount	2	2.1
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.75%	0.75%
Term Loan B (EUR) [Member]
Debt Instrument, Basis Spread on Variable Rate	2.25%	2.50%
Debt Instrument, Unamortized Discount	0.4	0.4
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	0.75%	0.75%
Other Debt Obligations [Member]
Debt, Long-term and Short-term, Combined Amount	$71.80	$82.30
Senior Notes, Due 2021 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.13%	5.13%
Senior Notes, Due 2024 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.63%	5.63%

Fair_Value_Measurements_and_Ri2

Fair Value Measurements and Risk Fair Value Measurements and Risk (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$2,232.60	$2,015.80
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	2,232.60	2,015.80
Other borrowings	131.4	142
Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	2,290.70	2,047.60
Other borrowings	131.4	142
Senior Notes, Due 2021 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.13%	5.13%
Senior Notes, Due 2021 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	700	700
Senior Notes, Due 2021 [Member] | Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	733.3	720.9
Senior Notes, Due 2024 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.63%	5.63%
Senior Notes, Due 2024 [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	300	300
Senior Notes, Due 2024 [Member] | Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	321	312
Term Loan B (USD) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Unamortized Discount	2	2.1
Term Loan B (USD) [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	940.4	692.6
Term Loan B (USD) [Member] | Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	943.6	691.3
Term Loan B (EUR) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Unamortized Discount	0.4	0.4
Term Loan B (EUR) [Member] | Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	160.8	181.2
Term Loan B (EUR) [Member] | Portion at Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt, Long-term and Short-term, Combined Amount	$161.40	$181.40

Fair_Value_Measurements_and_Ri3

Fair Value Measurements and Risk (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Items measured at Fair Value on a Recurring Basis
Number of Countries in which Entity Operates	40
Number of Currencies Used	50
Derivative, Fixed Interest Rate	2.39%
Recurring basis
Assets
Currency derivatives	9.8	$3.30
Total Assets	9.8	3.3
Liabilities
Currency derivatives	0.4	0.1
Interest rate derivatives	9	5.5
Commodity derivatives	2.7	2.6
Total Liabilities	12.1	8.2
Recurring basis | Fair Value, Inputs, Level 1 [Member]
Assets
Currency derivatives	0	0
Total Assets	0	0
Liabilities
Currency derivatives	0	0
Interest rate derivatives	0	0
Commodity derivatives	0	0
Total Liabilities	0	0
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets
Currency derivatives	9.8	3.3
Total Assets	9.8	3.3
Liabilities
Currency derivatives	0.4	0.1
Interest rate derivatives	9	5.5
Commodity derivatives	2.7	2.6
Total Liabilities	12.1	8.2
Recurring basis | Fair Value, Inputs, Level 3 [Member]
Assets
Currency derivatives	0	0
Total Assets	0	0
Liabilities
Currency derivatives	0	0
Interest rate derivatives	0	0
Commodity derivatives	0	0
Total Liabilities	0	0
Fixed-rate natural gas swaps
Items measured at Fair Value on a Recurring Basis
Maximum period of cash flow hedging	12 months
Commodity Contract [Member]
Items measured at Fair Value on a Recurring Basis
Derivative, Nonmonetary Notional Amount, Energy Measure	3,700,000
Derivative, Notional Amount	12.9
Commodity Option [Member]
Items measured at Fair Value on a Recurring Basis
Maximum period of cash flow hedging	24 months
Derivative, Nonmonetary Notional Amount, Energy Measure	200,000
Fixed-rate aluminum swaps
Items measured at Fair Value on a Recurring Basis
Maximum period of cash flow hedging	12 months
Derivative, Notional Amount	1.2
Derivative, Nonmonetary Notional Amount, Mass	1,400,000
Interest Rate Swap [Member]
Items measured at Fair Value on a Recurring Basis
Derivative, Notional Amount	250

Fair_Value_Measurements_and_Ri4

Fair Value Measurements and Risk (Details 3) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Fair values of derivative instruments
Asset Derivatives	$9.80	$3.30
Liability Derivatives	12.1	8.2
Designated as Hedging Instrument [Member] | Other current assets
Fair values of derivative instruments
Asset Derivatives, Commodity contracts	0	0
Asset Derivatives, Currency contracts	6.5	0.8
Interest Rate Fair Value Hedge Asset at Fair Value	0	0
Designated as Hedging Instrument [Member] | Other current liabilities
Fair values of derivative instruments
Liability Derivatives, Commodity contracts	2.7	2.6
Liability Derivatives, Currency contracts	0	0
Interest Rate Fair Value Hedge Liability at Fair Value	3.9	2.5
Designated as Hedging Instrument [Member] | Other Assets
Fair values of derivative instruments
Asset Derivatives, Currency contracts	3.1	0.9
Interest Rate Fair Value Hedge Asset at Fair Value	0	0
Designated as Hedging Instrument [Member] | Other Liabilities
Fair values of derivative instruments
Liability Derivatives, Currency contracts	0	0
Interest Rate Fair Value Hedge Liability at Fair Value	5.1	3
Not Designated as Hedging Instrument [Member] | Other current assets
Fair values of derivative instruments
Asset Derivatives, Currency contracts	0.2	1.6
Not Designated as Hedging Instrument [Member] | Other current liabilities
Fair values of derivative instruments
Liability Derivatives, Currency contracts	$0.40	$0.10

Fair_Value_Measurements_and_Ri5

Fair Value Measurements and Risk (Details 4)

3 Months Ended

3 Months Ended

In Millions, unless otherwise specified

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

USD ($)

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Cash Flow Hedging [Member]

Net Investment Hedging [Member]

Term Loan B (EUR) [Member]

Not Designated as Hedging Instrument [Member]

Not Designated as Hedging Instrument [Member]

USD ($)

USD ($)

Interest Rate Contract [Member]

Interest Rate Contract [Member]

Currency contracts

Currency contracts

Currency contracts

Commodity Contract [Member]

Commodity Contract [Member]

USD ($)

EUR (€)

Currency contracts

Currency contracts

Interest Expense [Member]

Interest Expense [Member]

Other income (expense)

Other income (expense)

Cost of goods sold

Cost of goods sold

Cost of goods sold

Other income (expense)

Other income (expense)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Gains and losses on derivative instruments

Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net

$2

$1.90

($3.50)

$1

$6.40

$0.50

$0.10

($1)

$0.40

Gain (loss) from hedging activities

4.9

0.8

-0.6

0

6.5

0.5

0

-1

0.3

Amount of Gain or (Loss) Recognized in Income on Derivative

-0.5

4.5

Senior Secured Credit Facility to Fund Emergence

148.5

Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion)

20

Nonderivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Ineffective Portion, Net

$0

$0

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, Percent	35.00%	17.10%
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards		$1,300
US Federal Income Tax Deductions Generated at Emergence		670
Cash paid to settle deferred payment obligations		632
US Federal Income Tax Deduction Upon Settlement of Warrant Held by Asbestos Trusts		490
Expected Income Tax Deductions Generated from Deferred Payment Obligation	30
Period Allowed for Carryforward of Operating Loss	20 years
Deferred Tax Assets, Net of Deferred Tax Liabilities	819.5
Deferred Tax Assets, Valuation Allowance	-12.5
Deferred Tax Assets, Net	807
Income Tax Contingency Netted Against Related DTA	5.7
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Other Information	12 months
Decrease in unrecognized tax benefits during the next 12 months	3
Taxable Income Required to Realize DTA, Total	2,000
Taxable Income Required to Realize DTA, Per Year	100
Internal Revenue Service (IRS) [Member]
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Net of Deferred Tax Liabilities	717.1
Deferred Tax Assets, Valuation Allowance	-2.4
Deferred Tax Assets, Net	714.7
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Net of Deferred Tax Liabilities	61.4
Deferred Tax Assets, Valuation Allowance	-5.9
Deferred Tax Assets, Net	55.5
GERMANY
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Net of Deferred Tax Liabilities	35.5
Deferred Tax Assets, Valuation Allowance	0
Deferred Tax Assets, Net	35.5
Foreign Tax Authority [Member]
Tax Credit Carryforward [Line Items]
Deferred Tax Assets, Net of Deferred Tax Liabilities	5.5
Deferred Tax Assets, Valuation Allowance	-4.2
Deferred Tax Assets, Net	$1.30
Maximum [Member] | Internal Revenue Service (IRS) [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	31-Dec-35
Maximum [Member] | State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	31-Dec-35
Minimum [Member] | Internal Revenue Service (IRS) [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	31-Dec-34
Minimum [Member] | State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Operating Loss Carryforwards, Expiration Date	31-Dec-15

Pension_Plans_and_Other_Postre2

Pension Plans and Other Postretirement Benefit Plans (Details) (USD $)	3 Months Ended		5 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014	Oct. 31, 2014	Dec. 31, 2014
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	$43.10			$44.10
Total underfunded and unfunded defined benefit pension plans	-428.9			-457.5
Pension liabilities included in other current liabilities	-443.7
Postretirement Benefits Other Than Pensions
Percent of Net Actuarial Gains and Losses Over Accumulated Postretirement Benefit Obligation Recognized in Statement of Operations	10.00%
Other Comprehensive Income, Effect of Postretirement Plan Changes, Pre-tax, Net		41.9
Effect of Postretirement Plan Changes, Amortize Amount from OCI			39.5
Effect of Postretirement Plan Changes, Amortization Period	5 months
Pension Plans
Funded status of fully funded, underfunded, and unfunded pension plans:
Overfunded defined benefit pension plans	43.1			44.1
Underfunded defined benefit pension plans	79.7			79.5
Unfunded defined benefit pension plans	349.2			378
Total underfunded and unfunded defined benefit pension plans	-428.9			-457.5
Pension liabilities included in other current liabilities	-14.8			-15.6
Net funded status	($400.60)			($429)
Postretirement Benefits Other Than Pensions
Postretirement Benefits Other Than Pensions
Minimum eligible age for medical plan benefits	55 years
Minimum eligible tenure of service for medical plan benefits	10 years

Pension_Plans_and_Other_Postre3

Pension Plans and Other Postretirement Benefit Plans (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net Periodic Benefit Cost
Mark-to-market adjustment	$4.70	($4.80)
Defined Benefit Plan, Measurement Date		1-Mar-14
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	4.1	3.3
U.S. qualified pension plans
Net Periodic Benefit Cost
Service cost	6.4	5.9
Interest cost	13.8	15.2
Expected return on plan assets	-17.6	-17.5
Amortization of prior service cost (credit)	0.1	0.2
Amortization of net deferred actuarial loss (gain)	0	0
Mark-to-market adjustment	0	-3.1
Net periodic benefit cost (income)	2.7	0.7
Benefit Payments from Nonqualified Plans Related to Emergence	27
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		4.43%
Non-U.S. pension plans
Net Periodic Benefit Cost
Service cost	3	2.7
Interest cost	4.2	5.7
Expected return on plan assets	-3.4	-3.9
Amortization of prior service cost (credit)	0	0
Amortization of net deferred actuarial loss (gain)	0	0
Mark-to-market adjustment	0	0
Net periodic benefit cost (income)	3.8	4.5
Postretirement Benefits Other Than Pensions
Net Periodic Benefit Cost
Service cost	0	0
Interest cost	0.1	0.6
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	-1	-0.1
Amortization of net deferred actuarial loss (gain)	0.2	-0.2
Mark-to-market adjustment	0	0
Net periodic benefit cost (income)	($0.70)	$0.30

Other_Balance_Sheet_Accounts_D

Other Balance Sheet Accounts (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Other Current Liabilities
Accrued compensation	$67.70	$77
Income tax payable	34.8	34.1
Accrued interest	25.5	21
Customer volume rebates	24.9	37.8
Deferred revenue	19.3	19.4
Pension liabilities	14.8	15.6
Environmental contingencies	14	21.5
Deferred tax liability	1.6	1.5
Other accrued liabilities	113.3	112.1
Total Other Current Liabilities	$315.90	$340

Commitments_and_Contingent_Lia1

Commitments and Contingent Liabilities (Details) (USD $)	3 Months Ended		12 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2010	Dec. 31, 2014	Feb. 03, 2014
	payment		facility
	claim
Other Commitments Chapter 11 [Abstract]
ZAI PD Account Funding					$34.40
ZAI P D Account, Payment on Third Anniversary of Effective Date of Joint Plan	30
Deferred payment obligation	28.4			28.2
ZAI P D Account, Maximum Number of Contingent Deferred Payments	10
ZAI P D Account, Deferred Payments, Each Year for Twenty Years	8
Period in Which ZAI PD Contingent Deferred Payments Will be Made	20 years
Minimum ZAI P D Account Assets for Condition in Relation to Contingent Obligation Payments	10
Frequency of PD Trust Payments	6 months
PD Claims Accrual Post Effective Date	0.4
PD Claims Filed After Effective Date	2
Number of Shares Issuable under Warrant	77,372,257
Environmental remediation
Estimated liability for environmental investigative and remediation costs	54.2			61.7
Net cash expenditures	4.2	1.8
Vermiculite Related Matters
Environmental remediation
Estimated liability for environmental investigative and remediation costs	13.4			19.4
Maximum number of operating plants under U.S. Environmental Protection Agency (EPA) reinvestigation			105
Non-Vermiculite Related Matters
Environmental remediation
Estimated liability for environmental investigative and remediation costs	$40.80			$42.30

Commitments_and_Contingent_Lia2

Commitments and Contingent Liabilities (Details 2) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Financial Guarantee
Financial assurances
Gross financial assurances issued and outstanding	$134.40
Surety Bonds
Financial assurances
Gross financial assurances issued and outstanding	34.2
Standby Letters of Credit
Financial assurances
Gross financial assurances issued and outstanding	$100.20

Restructuring_Expenses_and_Ass2

Restructuring Expenses and Asset Impairments (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Restructuring Expenses (In millions)
Restructuring expenses	$9.50	$0.70
Total restructuring expenses	9.5	0.7
Restructuring Liability (In millions)
Balance, December 31, 2014	4.5
Restructuring expenses	9.5	0.7
Payments	-3.7	-1.9
Currency translation adjustments and other	0.1
Balance, March 31, 2015	10.4
Grace Construction Products
Restructuring Expenses (In millions)
Restructuring expenses	2.3
Restructuring Liability (In millions)
Restructuring expenses	2.3
Grace Materials Technologies [Member]
Restructuring Expenses (In millions)
Restructuring expenses	0.6
Restructuring Liability (In millions)
Restructuring expenses	0.6
Grace Catalysts Technologies [Member]
Restructuring Expenses (In millions)
Restructuring expenses	2.6
Restructuring Liability (In millions)
Restructuring expenses	2.6
Corporate Segment [Member]
Restructuring Expenses (In millions)
Restructuring expenses	4
Restructuring Liability (In millions)
Restructuring expenses	$4

Other_Income_Expense_net_Detai

Other (Income) Expense, net (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Income and Expenses [Abstract]
Gain related to release of bankruptcy liabilities	$9
Total restructuring expenses	9.5	0.7
Asbestos and bankruptcy related charges, net	-8.7	8.8
Repositioning expenses	6.9	0
Provision for environmental remediation, net	-3.3	1.2
Currency transaction effects	-2.8	0.3
Net loss on sales of investments and disposals of assets	-0.4	-0.7
Interest income	0.1	0.5
Other miscellaneous income	0.6	1.2
Total other expense, net	$1.30	$10

Other_Comprehensive_Income_Det

Other Comprehensive Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Defined benefit pension and other postretirement plans, Pre-Tax Amount
Amortization of net prior service cost included in net periodic benefit cost, Pre-Tax Amount	($0.90)	$0.10
Amortization of net deferred actuarial loss included in net periodic benefit cost, Pre-Tax Amount	0.2	-0.2
Benefit plans, net, Pre-Tax Amount	0.7	0.1
Currency translation adjustments, pre-tax amount	-10.8	-2.1
Loss from hedging activities, pre-tax amount	-2.9	1.1
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent		0.1
Other comprehensive income attributable to W. R. Grace and Co. shareholders, Pre-Tax Amount	-14.4	-1
Defined benefit pension and other postretirement plans, Tax Benefit/(Expense)
Amortization of net prior service credit included in net periodic benefit cost, tax benefit/(expense)	0.4	0
Amortization of net deferred actuarial gain included in net periodic benefit cost, tax benefit/(expense)	-0.1	0
Benefit plans, net, Tax Benefit/(Expense)	0.3	0
Currency translation adjustments, tax benefit/(expense)	0	0
Loss from hedging activities, tax benefit/(expense)	1	-0.4
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent		0
Other comprehensive income attributable to W. R. Grace and Co. shareholders, Tax Benefit/(Expense)	1.3	-0.4
Defined benefit pension and other postretirement plans, After-Tax Amount:
Amortization of net prior service credit included in net periodic benefit cost, After-Tax Amount	-0.5	0.1
Amortization of net deferred actuarial loss included in net periodic benefit cost, After-Tax Amount	0.1	-0.2
Benefit plans, net, after-tax amount	-0.4	-0.1
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	-10.8	-2.1
Gain (loss) from hedging activities, net of income taxes	-1.9	0.7
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	0	0.1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	($13.10)	($1.40)

Other_Comprehensive_Income_Det1

Other Comprehensive Income (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
	country
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	($3.60)	($6.50)	($4)	($6.60)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	-33.6	3.1	-22.8	5.2
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	-6.9	0.2	-5	-0.5
Accumulated Other Comprehensive Income (Loss), Unrealized loss on investment		-0.8		-0.8
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax		0.2		0.1
Accumulated Other Comprehensive Income (Loss), Net of Tax	-36.9	9.2	-23.8	10.6
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Plan Amendments, Net of Tax	0	0
Other comprehensive income (loss) foreign currency transaction and translation adjustment before reclassification, net of tax	-10.8	-2.1
Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Net of Tax, Portion Attributable to Parent	2.3	1.2
Other Comprehensive Income Loss, before Reclassification, Unrealized Loss on Investment, Net Of Tax		0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax		0.1
Other Comprehensive Income (Loss) before reclassifications, Net of Tax, Portion Attributable to Parent, Total	-8.5	-0.8
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	0.4	0.1
Other Comprehensive Income Loss, Reclassification, Currency Translation Adjustment, Net Of Tax	0	0
Reclassification From Accumulated Other Comprehensive Income, Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Current Period Net Of Tax	4.2	0.5
Reclassification from Accumulated Other Comprehensive Income (Loss), Unrealized loss on investment		0
Other Comprehensive Income Loss, Reclassification Adjustment on Securities Available for Sale, Net Of Tax		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	4.6	0.6
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax, Portion Attributable to Parent	0.4	0.1
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	-10.8	-2.1
Gain (loss) from hedging activities, net of income taxes	-1.9	0.7
Accumulated Other Comprehensive Income (Loss), Unrealized loss on investment, Net of Tax, Portion Attributable to Parent		0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent	0	0.1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	($13.10)	($1.40)
Number of Countries in which Entity Operates	40

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Numerators
Net income attributable to W. R. Grace & Co. shareholders	$52.70	$50.10
Denominators
Weighted average common shares—basic calculation	72,800,000	77,000,000
Dilutive effect of employee stock options	700,000	1,100,000
Weighted average common shares—diluted calculation	73,500,000	78,100,000
Basic earnings per share	$0.72	$0.65
Diluted earnings per share	$0.72	$0.64
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	200,000	0
Stock Repurchase Program, Number of Shares Authorized to be Repurchased	500,000,000		500,000,000
Stock Repurchased During Period, Shares	581,204
Payments for Repurchase of Common Stock	$55.60	$60.50
Minimum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock Repurchase Program, Period in Force	12 months
Maximum [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock Repurchase Program, Period in Force	24 months

Operating_Segment_Information_1

Operating Segment Information (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	segment
Segment Reporting [Abstract]
Number of operating segments	3
Net Sales
Net sales	$720.60	$744.50
Reconciliation of operating segment data to financial statements
Grace Adjusted EBIT	117	111.3
Benefit (costs) related to Chapter 11 and asbestos, net	9.7	-15.5
Pension MTM adjustment and other related costs, net	-4.7	4.8
Restructuring expenses	-9.5	-0.7
Repositioning expenses	-6.9	0
Income and expense items related to divested businesses	-0.7	1.1
Interest expense, net	-24.9	-18.9
Net income attributable to noncontrolling interests	0.1	0.2
Income before income taxes	81.5	80.1
Grace Catalysts Technologies [Member]
Net Sales
Net sales	281	284.5
Adjusted EBIT
Operating income	73.7	71.2
Grace Materials Technologies [Member]
Net Sales
Net sales	200.3	219.8
Adjusted EBIT
Operating income	41	45.5
Construction Products
Net Sales
Net sales	239.3	240.2
Adjusted EBIT
Operating income	29.4	25.4
Corporate, Non-Segment [Member]
Adjusted EBIT
Operating income	-20.6	-22.5
Certain pension costs	$6.50	$8.30

Operating_Segment_Information_2

Operating Segment Information (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Geographic Area Data
Net sales	$720.60	$744.50
Total North America
Geographic Area Data
Net sales	232.4	222.6
UNITED STATES
Geographic Area Data
Net sales	214.6	206
Canada and Puerto Rico
Geographic Area Data
Net sales	17.8	16.6
Europe Middle East Africa
Geographic Area Data
Net sales	235.2	274.9
Asia Pacific
Geographic Area Data
Net sales	176.6	164.9
Latin America
Geographic Area Data
Net sales	$76.40	$82.10

Unconsolidated_Affiliate_Detai

Unconsolidated Affiliate (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Investment in unconsolidated affiliates
Equity method investment, ownership interest (as a percent)	50.00%
Investment in unconsolidated affiliate	$106.60		$113.10
Equity in earnings of unconsolidated affiliate	6.2	3.7
Grace sales of catalysts to ART	54.2	65.5
Charges for fixed costs, research and development and selling, general and administrative services to ART	5.9	7.5
Commitment fee on credit facility (as a percent)	0.10%
Parent Company [Member]
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	15
Corporate Joint Venture [Member]
Investment in unconsolidated affiliates
Line of credit facility, maximum provided by Grace and Chevron each	$15