Operating Segment Information - Reportable Segment Data (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)
Operating segment information
Number of Reportable Segments | segment			2
Number of operating segments | segment			2
Net Sales
Net sales	$ 429.5	$ 404.5	$ 1,257.0	$ 1,157.8
Adjusted EBIT
Total	108.1	102.7	298.9	281.4
Reconciliation of operating segment data to financial statements
(Costs) benefit related to legacy product, environmental and other claims	8.5	13.1	25.5	24.2
Restructuring and repositioning expenses	9.3	5.6	17.0	28.6
Accounts receivable reserve-Venezuela	(10.0)	0.0	(10.0)	0.0
Pension MTM adjustment and other related costs, net	0.0	(0.2)	1.9	(1.1)
Income and expense items related to divested businesses	0.3	0.1	1.3	0.3
Third-party acquisition-related costs	0.4	0.0	0.4	2.5
Amortization of acquired inventory fair value adjustment	0.0	4.1	0.0	4.1
Gain on sale of product line	(0.4)	0.0	(0.4)	0.7
Loss on early extinguishment of debt	0.0	0.0	0.0	(11.1)
Interest expense, net	(20.2)	(19.4)	(59.0)	(60.6)
Net income (loss) attributable to noncontrolling interests	0.3	(0.1)	0.7	0.3
Income (loss) from continuing operations before income taxes	58.7	60.7	$ 182.7	151.5
Grace Catalysts Technologies [Member]
Operating segment information
Number of Reportable Segments | segment			1
Adjusted EBIT
Operating income	103.6	94.3	$ 286.1	260.1
Grace Materials Technologies [Member]
Adjusted EBIT
Operating income	26.4	26.4	75.4	75.0
Corporate, Non-Segment [Member]
Adjusted EBIT
Operating income			(52.9)	(44.4)
Certain pension costs	(3.4)	(3.1)	(9.7)	(9.3)
Operating Segments | Grace Catalysts Technologies [Member]
Net Sales
Net sales	317.5	295.8	931.8	834.8
Operating Segments | Grace Materials Technologies [Member]
Net Sales
Net sales	112.0	108.7	$ 325.2	$ 323.0
Corporate, Non-Segment [Member]
Adjusted EBIT
Operating income	$ (18.5)	$ (14.9)