Restructuring Costs - By Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	$ 12.0	$ 20.3	$ 35.0
Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	8.2	13.7	27.5
Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	3.8	6.6	7.5
Electrical
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	8.3	16.9	33.9
Electrical | Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	4.9	11.5	27.3
Electrical | Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	3.4	5.4	6.6
Power
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	3.7	3.4	1.1
Power | Cost of goods sold
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	3.3	2.2	0.2
Power | Selling & administrative expense
Restructuring Cost and Reserve [Line Items]
Pre-tax Restructuring Costs	$ 0.4	$ 1.2	$ 0.9