Goodwill and Other Intangible Assets Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 928.5	$ 874.7
Current year acquisitions	70.0	55.3
Foreign currency translation and prior year acquisitions	(7.5)	(1.5)
Goodwill, end of period	991.0	928.5
Electrical
Goodwill [Roll Forward]
Goodwill, beginning of period	611.2	568.9
Current year acquisitions	49.4	43.3
Foreign currency translation and prior year acquisitions	(8.6)	(1.0)
Goodwill, end of period	652.0	611.2
Power
Goodwill [Roll Forward]
Goodwill, beginning of period	317.3	305.8
Current year acquisitions	20.6	12.0
Foreign currency translation and prior year acquisitions	1.1	(0.5)
Goodwill, end of period	$ 339.0	$ 317.3