Debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended								1 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended	1 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Feb. 28, 2014	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Feb. 03, 2014	May 31, 2003	May 31, 2001	Feb. 28, 2014	Dec. 31, 2013	Dec. 31, 2013 Revolving Credit Facility [Member]	Feb. 03, 2014 Revolving Credit Facility [Member]	Feb. 28, 2014 Term Loan B (EUR) [Member]	Dec. 31, 2013 Term Loan B (EUR) [Member]	Feb. 28, 2014 Delayed-Draw Term Loan B [Member]	Dec. 31, 2013 Delayed-Draw Term Loan B [Member]	Mar. 31, 2013 Unallocated Amount to Segment [Member]	Dec. 31, 2012 Unallocated Amount to Segment [Member]	Dec. 31, 2011 Unallocated Amount to Segment [Member]
Exchange Rate Net Charges		$ (8.5)		$ 0		$ 0												$ 6.9	$ 0	$ 0
Senior Secured Credit Facilities to Fund Emergence	900									700				150		250
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum												75.00%			75.00%		75.00%
Term Loans, Percent of Original Principal Annual Amortization Amounts		1.00%
Debt payable within one year		76.6	[1]	83.4	[1]
Debt payable after one year		5.3		13.4
Debt Subject to Compromise
Bank borrowings		500.0	[2],[3]	500.0	[2],[3]
Accrued interest on bank borrowings		471.0	[2]	437.2	[2]
Default interest settlement liability on prepetition debt		129.0		0
Drawn letters of credit		26.7	[2]	26.5	[2]
Accrued interest on drawn letters of credit		11.1	[2]	9.6	[2]
Debt Subject to Compromise		1,137.8		973.3
Debt Instrument, Basis Spread on Variable Rate											225.00%		175.00%		250.00%		225.00%
Line of Credit Facility, Amount Outstanding							400						400
Length of Delayed Draw Term Loan Facility																	12 months
Full-year weighted average interest rates on total debt		3.60%		3.50%
Maximum borrowing amount of revolving credit agreements, prior to the Filing		500
Maximum borrowing amount of short-term credit facilities, prior to the Filing									250
Maximum borrowing amount of long-term credit facilities, prior to the Filing								$ 250

[1] Represents borrowings under various lines of credit and other borrowings, primarily by non-U.S. subsidiaries. At December 31, 2013, the fair value of Grace's debt payable within one year not subject to compromise approximated the recorded value of $76.6 million.

[2] At December 31, 2013, the carrying value of Grace's bank debt subject to compromise plus interest was $1,137.8 million. The estimated fair value of the bank debt approximates the carrying value and is estimated using Level 2 inputs.

[3] Under bank revolving credit agreements in effect prior to the Filing, Grace could borrow up to $500 million at interest rates based upon the prevailing prime, federal funds and/or Eurodollar rates. Of that amount, $250 million was available under short-term facilities that expired in May 2001, and $250 million was available under a long-term facility that expired in May 2003. As a result of the Filing, Grace was not permitted to make payments under the bank revolving credit agreements, and accordingly, the balance as of the Filing Date was reclassified to debt subject to compromise in the Consolidated Balance Sheets.