Restructuring Costs and Other - By Segment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0.0	$ 4.8	$ 0.7	$ 10.2
Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.4	3.2	1.2	7.4
Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.4)	1.6	(0.5)	2.8
Electrical Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	3.9	0.7	8.6
Electrical Segment | Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.3	2.5	1.1	6.3
Electrical Segment | Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(0.3)	1.4	(0.4)	2.3
Power Segment
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.0	0.9	0.0	1.6
Power Segment | Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0.1	0.7	0.1	1.1
Power Segment | Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ (0.1)	$ 0.2	$ (0.1)	$ 0.5