Operating Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Operating segment information
Number of operating segments									3
Net Sales
Net sales	$ 797.8	$ 776.6	$ 826.7	$ 754.4	$ 825.6	$ 864.2	$ 826.4	$ 695.7	$ 3,155.5	$ 3,211.9	$ 2,675.0
Adjusted EBIT
Defined benefit pension expense									(71.2)	(63.4)	(77.1)
Grace Adjusted EBIT									517.4	478.6	326.4
Depreciation and Amortization									119.0	120.0	115.6
Capital Expenditures									138.5	144.0	111.1
Total Assets	5,090.2				4,494.0				5,090.2	4,494.0	4,271.7
Reconciliation of operating segment data to financial statements
Grace Adjusted EBIT									517.4	478.6	326.4
Chapter 11- and asbestos-related costs, net									(407.8)	(44.7)	(35.3)
Restructuring expenses and related asset impairments									(6.9)	(6.9)	(11.2)
Loss on sale of product line									(0.2)	(0.4)
Divestment expenses									(0.2)	(0.4)
Interest expense and related financing costs									(46.5)	(43.3)	(41.3)
Interest income of non-Debtor subsidiaries									1.0	1.2	1.0
Net (loss) income attributable to noncontrolling interests									1.0	(0.6)	0.3
Income before income taxes									57.8	383.5	239.9
Catalysts Technologies
Net Sales
Net sales									1,268.1	1,347.3	982.3
Adjusted EBIT
Operating income (loss)									393.8	388.8	239.6
Depreciation and Amortization									54.0	52.5	48.7
Capital Expenditures									70.8	74.5	62.0
Total Assets	794.8				804.5				794.8	804.5	672.7
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments									(0.2)	(0.4)
Materials Technologies
Net Sales
Net sales									862.6	872.6	819.4
Adjusted EBIT
Operating income (loss)									162.0	158.7	160.0
Depreciation and Amortization									29.5	30.9	31.8
Capital Expenditures									27.1	32.3	20.3
Total Assets	494.9				481.1				494.9	481.1	458.4
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments									(1.0)	(0.3)
Construction Products
Net Sales
Net sales									1,024.8	992.0	873.3
Adjusted EBIT
Operating income (loss)									125.2	97.3	89.9
Depreciation and Amortization									32.9	34.0	32.5
Capital Expenditures									26.5	19.5	19.6
Total Assets	616.0				545.9				616.0	545.9	486.0
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments									(2.0)	(6.5)
Corporate costs
Adjusted EBIT
Operating income (loss)									(92.4)	(102.8)	(86.0)
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments									(3.7)	0.3
Corporate
Adjusted EBIT
Depreciation and Amortization									2.6	2.6	2.6
Capital Expenditures									14.1	17.7	9.2
Total Assets	$ 3,184.5				$ 2,662.5				$ 3,184.5	$ 2,662.5	$ 2,654.6