Industry Segments and Geographic Area Information - Industry Segments Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Sales:
Net sales	$ 1,037.9	$ 1,108.6	$ 949.2	$ 1,090.3	$ 1,103.3	$ 1,204.0	$ 1,196.4	$ 1,087.3	$ 4,186.0	$ 4,591.0	$ 4,481.7
Operating Income:
Operating Income									533.0	596.6	556.9
Gain on disposition of business (Note 3)									0.0	21.7	0.0
Pension charge (Note 11 & 15)									(7.6)	(8.5)	0.0
Interest expense									(60.3)	(69.4)	(72.4)
Investment income and other expense, net									(11.6)	(19.9)	(17.5)
Income before income taxes									453.5	520.5	467.0
Assets:
Assets	5,085.1				4,903.0				5,085.1	4,903.0	4,872.1
Capital Expenditures:
Capital expenditures									88.4	93.9	96.2
Depreciation and Amortization:
Depreciation and amortization									157.6	151.0	148.4
Electrical Solutions
Net Sales:
Net sales									2,263.6	2,625.7	2,660.6
Utility Solutions
Net Sales:
Net sales									1,922.4	1,965.3	1,821.1
Operating Segments | Electrical Solutions
Net Sales:
Net sales									2,263.6	2,625.7	2,660.6
Operating Income:
Operating Income									234.8	320.1	320.8
Assets:
Assets	2,233.0				2,197.8				2,233.0	2,197.8	2,228.5
Capital Expenditures:
Capital expenditures									34.8	45.8	53.0
Depreciation and Amortization:
Depreciation and amortization									65.1	65.0	61.4
Operating Segments | Utility Solutions
Net Sales:
Net sales									1,922.4	1,965.3	1,821.1
Operating Income:
Operating Income									298.2	276.5	236.1
Assets:
Assets	2,563.8				2,401.3				2,563.8	2,401.3	2,395.8
Capital Expenditures:
Capital expenditures									53.1	45.4	36.8
Depreciation and Amortization:
Depreciation and amortization									92.5	86.0	87.0
General Corporate
Assets:
Assets	$ 288.3				$ 303.9				288.3	303.9	247.8
Capital Expenditures:
Capital expenditures									$ 0.5	$ 2.7	$ 6.4