Restructuring Costs - Summary of Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Expected Costs	$ 78.5
Cost incurred to date	20.3	$ 35.0	$ 19.2
Remaining costs at 12/31/17	4.0
2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	16.9
Cost incurred to date	14.0	0.0
Remaining costs at 12/31/17	2.9
2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	36.7
Cost incurred to date	3.8	31.8
Remaining costs at 12/31/17	1.1
2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	24.9
Cost incurred to date	2.5	3.2	19.2
Remaining costs at 12/31/17	0.0
Electrical | 2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	13.0
Cost incurred to date	10.6	0.0
Remaining costs at 12/31/17	2.4
Electrical | 2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	35.4
Cost incurred to date	3.8	30.7
Remaining costs at 12/31/17	0.9
Electrical | 2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	23.0
Cost incurred to date	2.5	3.2	17.3
Remaining costs at 12/31/17	0.0
Power | 2017 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	3.9
Cost incurred to date	3.4	0.0
Remaining costs at 12/31/17	0.5
Power | 2016 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	1.3
Cost incurred to date	0.0	$ 1.1
Remaining costs at 12/31/17	0.2
Power | 2015 Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Expected Costs	$ 1.9
Cost incurred to date			$ 1.9