Segment Information - Reportable Segment Data (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)
Operating segment information
Number of reportable segments | segment			2
Net Sales
Net sales	$ 485.7	$ 429.5	$ 917.2	$ 827.5
Adjusted EBIT
Total	119.5	104.0	215.3	190.8
Reconciliation of operating segment data to financial statements
Restructuring and repositioning expenses	(18.8)	(5.4)	(24.4)	(7.7)
Third-party acquisition-related costs	(5.8)	0.0	(6.7)	0.0
Loss on early extinguishment of debt	(4.8)	0.0	(4.8)	0.0
Amortization of acquired inventory fair value adjustment	(4.6)	0.0	(4.6)	0.0
Costs related to legacy product, environmental and other claims	(2.8)	(14.9)	(4.3)	(17.0)
Income and expense items related to divested businesses	0.6	(0.7)	0.1	(1.0)
Pension MTM adjustment and other related costs, net	0.0	0.0	0.0	(1.9)
Interest expense, net	(19.5)	(19.5)	(38.4)	(38.8)
Net income (loss) attributable to noncontrolling interests	(0.2)	(0.4)	(0.4)	(0.4)
Income (loss) before income taxes	63.6	63.1	$ 131.8	124.0
Catalysts Technologies
Operating segment information
Number of reportable segments | segment			1
Number of operating segments | segment			2
Net Sales
Net sales	364.4	320.5	$ 680.2	614.3
Materials Technologies
Net Sales
Net sales	121.3	109.0	237.0	213.2
Corporate
Adjusted EBIT
Operating income	(19.8)	(18.3)	(36.4)	(34.4)
Certain pension costs	(4.0)	(3.2)	(7.8)	(6.3)
Operating Segments | Catalysts Technologies
Net Sales
Net sales	364.4	320.5	680.2	614.3
Adjusted EBIT
Operating income	113.7	101.3	205.8	182.5
Operating Segments | Materials Technologies
Net Sales
Net sales	121.3	109.0	237.0	213.2
Adjusted EBIT
Operating income	$ 29.6	$ 24.2	$ 53.7	$ 49.0