SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS AND RESERVES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowances for notes and accounts receivable
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	$ 9.8		$ 8.7		$ 9.6
Additions charged to costs and expenses	1.9		2.9		2.1
Deductions	(4.8)		(2.0)		(3.1)
Other net	0	[1]	0.2	[1]	0.1	[1]
Balance at end of period	6.9		9.8		8.7
Valuation allowance for deferred tax assets
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	100.8	[2]	104.6	[2]	107.8	[2]
Additions charged to costs and expenses	0	[2]	0	[2]	0	[2]
Deductions	(60.0)	[2]	(3.8)	[2]	(3.2)	[2]
Other net	0	[1],[2]	0	[1],[2]	0	[1],[2]
Balance at end of period	40.8	[2]	100.8	[2]	104.6	[2]
Reserves for asbestos related litigation
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	1,700.0		1,700.0		1,700.0
Additions charged to costs and expenses	365.0		0		0
Deductions	0		0		0
Other net	0	[1]	0	[1]	0	[1]
Balance at end of period	2,065.0		1,700.0		1,700.0
Reserves for environmental remediation
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	149.9		144.0		148.4
Additions charged to costs and expenses	3.6		17.8		4.5
Deductions	(13.0)		(11.8)		(8.0)
Other net	0	[1]	(0.1)	[1]	(0.9)	[1]
Balance at end of period	140.5		149.9		144.0
Reserves for retained obligations of divested businesses
Reconciliation of valuation and reserves roll forward
Balance at beginning of period	33.7		33.9		36.2
Additions charged to costs and expenses	0.7		0.4		0
Deductions	(0.2)		(0.6)		(2.3)
Other net	0	[1]	0	[1]	0	[1]
Balance at end of period	34.2		33.7		33.9
Net Operating Loss Carryforwards [Member] | State and Local Jurisdiction [Member]
Reconciliation of valuation and reserves roll forward
Reduction in valuation allowance	$ 44.0

[1] Various miscellaneous adjustments against reserves and effects of currency translation.

[2] The reduction in the valuation allowance during 2012 related in part to a $44.0 million release of the valuation allowance as Grace determined that it is more likely than not that a substantial portion of its state net operating losses will be used before their expiration; the remainder of the release related to the utilization and expiration of state net operating losses in the current year, and the reduction of net operating losses resulting from prior-year adjustments made to income by the Internal Revenue Service. The reductions in 2011 and 2010 primarily related to the utilization and expiration of state net operating losses.