Restructuring Expenses and Repositioning Expenses - Expenses and Asset Impairments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 0.2	$ 1.1
Catalysts Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0.0	0.2
Materials Technologies
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	0.2	1.0
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 0.0	$ (0.1)