Restructuring and Repositioning Expenses, Asset Impairments - Restructuring Costs by Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Total restructuring expenses and asset impairments from continuing operations	$ 0.4	$ 4.4	$ 3.5	$ 5.0
Restructuring expenses and asset impairments reflected in discontinued operations	0.0	0.1	0.0	0.2
Total restructuring expenses and asset impairments	0.4	4.5	3.5	5.2
Operating Segments | SCC
Restructuring Cost and Reserve [Line Items]
Total restructuring expenses and asset impairments from continuing operations	0.3	1.3	2.6	1.9
Operating Segments | SBM
Restructuring Cost and Reserve [Line Items]
Total restructuring expenses and asset impairments from continuing operations	0.1	3.2	0.9	3.2
Corporate
Restructuring Cost and Reserve [Line Items]
Total restructuring expenses and asset impairments from continuing operations	$ 0.0	$ (0.1)	$ 0.0	$ (0.1)