Industry Segments and Geographic Area Information - Industry Segments Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Sales:
Net sales	$ 1,103.3	$ 1,204.0	$ 1,196.4	$ 1,087.3	$ 1,144.1	$ 1,179.7	$ 1,166.7	$ 991.2	$ 4,591.0	$ 4,481.7	$ 3,668.8
Operating Income:
Operating Income									596.6	556.9	518.8
Gain on disposition of business									21.7	0.0	0.0
Multi-employer pension charge									(8.5)	0.0	0.0
Interest expense									(69.4)	(72.4)	(44.9)
Loss on extinguishment of debt									0.0	0.0	10.1
Investment income and other expense, net									(19.9)	(17.5)	(20.7)
Income before income taxes									520.5	467.0	443.1
Assets:
Assets	4,903.0				4,872.1				4,903.0	4,872.1	3,720.6
Capital Expenditures:
Capital expenditures									93.9	96.2	79.7
Depreciation and Amortization:
Depreciation and amortization									151.0	148.4	98.2
Electrical
Net Sales:
Net sales									2,625.7	2,660.6	2,532.8
Power
Net Sales:
Net sales									1,965.3	1,821.1	1,136.0
Operating Segments | Electrical
Net Sales:
Net sales									2,625.7	2,660.6	2,532.8
Operating Income:
Operating Income									320.1	320.8	294.0
Assets:
Assets	2,197.8				2,228.5				2,197.8	2,228.5	2,344.7
Capital Expenditures:
Capital expenditures									45.8	53.0	48.0
Depreciation and Amortization:
Depreciation and amortization									65.0	61.4	64.7
Operating Segments | Power
Net Sales:
Net sales									1,965.3	1,821.1	1,136.0
Operating Income:
Operating Income									276.5	236.1	224.8
Assets:
Assets	2,401.3				2,395.8				2,401.3	2,395.8	1,102.2
Capital Expenditures:
Capital expenditures									45.4	36.8	29.0
Depreciation and Amortization:
Depreciation and amortization									86.0	87.0	33.5
General Corporate
Assets:
Assets	$ 303.9				$ 247.8				303.9	247.8	273.7
Capital Expenditures:
Capital expenditures									$ 2.7	$ 6.4	$ 2.7