Restructuring Costs and Other - Summary of Costs (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Total expected costs	$ 22.0
Costs incurred	3.0	$ 12.0
Remaining costs at 3/31/2019	7.0
2019 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Total expected costs	2.6
Costs incurred	2.5	0.0
Remaining costs at 3/31/2019	0.1
2019 Restructuring Actions | Electrical Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	1.2
Costs incurred	1.1	0.0
Remaining costs at 3/31/2019	0.1
2019 Restructuring Actions | Power Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	1.4
Costs incurred	1.4	0.0
Remaining costs at 3/31/2019	0.0
2018 and Prior Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Total expected costs	19.4
Costs incurred	0.5	12.0
Remaining costs at 3/31/2019	6.9
2018 and Prior Restructuring Actions | Electrical Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	14.3
Costs incurred	0.1	8.3
Remaining costs at 3/31/2019	5.9
2018 and Prior Restructuring Actions | Power Segment
Restructuring Cost and Reserve [Line Items]
Total expected costs	5.1
Costs incurred	0.4	$ 3.7
Remaining costs at 3/31/2019	$ 1.0