Restructuring Costs - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 20.3	$ 35.0	$ 23.6
Accrued liability settlement term		19 years
Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	$ 12.5
2016 Restructuring Actions
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 6.3
2016 Restructuring Actions | Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	12.5		12.5
Electrical
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs		$ 16.9	$ 33.9	$ 21.7
Electrical | 2016 Restructuring Actions | Withdrawal from Multiemployer Defined Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Pre-tax restructuring costs	$ 12.5