Operating Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012 segment	Mar. 31, 2011	Dec. 31, 2011
Operating Segment Information
Number of operating segments	3
Net Sales
Net Sales, Total	$ 754.4	$ 695.7
Adjusted EBIT
Defined benefit pension expense	(18.8)	(16.5)
Grace Adjusted EBIT	111.3	95.7
Total Assets	4,460.0		4,494.0
Depreciation and amortization	29.4	29.2
Reconciliation of operating segment data to financial statements
Grace Adjusted EBIT	111.3	95.7
Chapter 11- and asbestos-related costs, net	(5.2)	(5.7)
Restructuring expenses and related asset impairments	(3.0)	(0.2)
Divestment expenses	(0.2)
Interest expense and related financing costs	(11.3)	(10.4)
Interest income of non-Debtor subsidiaries	0.1	0.3
Net income (loss) attributable to noncontrolling interests	0.4	(0.2)
Income before income taxes	92.1	79.5
Grace Catalyst Products
Net Sales
Net Sales, Total	313.2	275.7
Adjusted EBIT
Segment operating income	99.2	77.9
Total Assets	813.2		804.5
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments	(0.5)
Grace Materials Products
Net Sales
Net Sales, Total	212.9	212.4
Adjusted EBIT
Segment operating income	35.8	40.4
Total Assets	494.0		481.1
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments	(0.3)
Grace Construction Products
Net Sales
Net Sales, Total	228.3	207.6
Adjusted EBIT
Segment operating income	20.5	16.3
Total Assets	558.4		545.9
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments	(0.7)
Corporate
Adjusted EBIT
Segment operating income	(25.4)	22.4
Total Assets	2,594.4		2,662.5
Reconciliation of operating segment data to financial statements
Restructuring expenses and related asset impairments	$ (1.5)