Operating Segment Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			3
Net Sales
Net sales	$ 782.1	$ 838.0	$ 1,502.7	$ 1,582.5
Adjusted EBIT
Gain on termination of postretirement plans related to current businesses	0.0	4.7	0.0	4.7
Reconciliation of operating segment data to financial statements
Grace Adjusted EBIT	156.8	166.1	273.8	277.4
(Costs) benefit related to Chapter 11 and asbestos, net	(2.7)	(1.5)	7.0	(17.0)
Pension MTM adjustment and other related costs, net	0.0	0.0	(4.7)	4.8
Gain on termination of postretirement plans related to divested businesses	0.0	3.2	0.0	3.2
Restructuring expenses and asset impairments	(4.4)	(11.7)	(13.9)	(12.4)
Repositioning expenses	(13.4)	0.0	(20.3)	0.0
Gain on sale of product line	0.0	0.2	0.0	0.2
Income and expense items related to divested businesses	0.4	3.6	(0.3)	4.7
Interest expense, net	(24.9)	(24.2)	(49.8)	(43.1)
Net income attributable to noncontrolling interests	0.1	0.5	0.2	0.7
Income before income taxes	111.1	129.0	192.6	209.1
Grace Catalysts Technologies [Member]
Net Sales
Net sales	289.3	313.2	570.3	597.7
Adjusted EBIT
Operating income	86.6	97.5	160.3	168.7
Grace Materials Technologies [Member]
Net Sales
Net sales	204.2	236.1	404.5	455.9
Adjusted EBIT
Operating income	45.7	49.7	86.7	95.2
Construction Products
Net Sales
Net sales	288.6	288.7	527.9	528.9
Adjusted EBIT
Operating income	53.9	45.0	83.3	70.4
Corporate, Non-Segment [Member]
Adjusted EBIT
Operating income	(23.1)	(22.8)	(43.7)	(45.3)
Certain pension costs	$ 6.3	$ 8.0	$ 12.8	$ 16.3