Goodwill and Intangible Assets, net - Changes in Goodwill (Details) $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($)
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2016	$ 991.0
Current year acquisitions (Note 2 – Business Acquisitions)	60.1
Foreign currency translation and prior year acquisitions	7.6
BALANCE JUNE 30, 2017	1,058.7
Electrical
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2016	652.0
Current year acquisitions (Note 2 – Business Acquisitions)	55.4
Foreign currency translation and prior year acquisitions	5.1
BALANCE JUNE 30, 2017	712.5
Power
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2016	339.0
Current year acquisitions (Note 2 – Business Acquisitions)	4.7
Foreign currency translation and prior year acquisitions	2.5
BALANCE JUNE 30, 2017	$ 346.2