Industry Segments Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Net Sales:
Net sales	$ 848.8	$ 895.3	$ 855.8	$ 759.5	$ 806.6	$ 835.9	$ 801.3	$ 740.1	$ 3,359.4	$ 3,183.9	$ 3,044.4
Operating Income:
Operating Income									517.4	507.6	471.8
Interest expense									(31.2)	(30.8)	(30.8)
Investment income and other expense, net									(0.7)	(3.0)	0.8
Income before income taxes									485.5	473.8	441.8
Assets:
Assets	3,322.8				3,187.2				3,322.8	3,187.2	2,947.0
Capital Expenditures:
Capital expenditures									60.3	58.8	49.1
Depreciation and Amortization:
Depreciation and amortization									79.2	70.6	66.8
Electrical
Net Sales:
Net sales									2,398.2	2,262.6	2,114.6
Operating Income:
Operating Income									337.9	341.1	303.7
Assets:
Assets	1,963.0				1,813.8				1,963.0	1,813.8	1,659.2
Capital Expenditures:
Capital expenditures									35.1	32.4	27.1
Depreciation and Amortization:
Depreciation and amortization									53.4	48.0	45.8
Power
Net Sales:
Net sales											929.8
Operating Income:
Operating Income									179.5	166.5	168.1
Assets:
Assets	832.0				707.0				832.0	707.0	710.4
Capital Expenditures:
Capital expenditures									21.8	25.0	20.4
Depreciation and Amortization:
Depreciation and amortization									25.8	22.6	21.0
General Corporate
Assets:
Assets	527.8				666.4				527.8	666.4	577.4
Capital Expenditures:
Capital expenditures									$ 3.4	$ 1.4	$ 1.6