Goodwill and Intangible Assets, net - Changes in Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2018	$ 1,784.4
Foreign currency translation	2.4
BALANCE MARCH 31, 2019	1,786.8
Electrical
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2018	714.1
Foreign currency translation	1.7
BALANCE MARCH 31, 2019	715.8
Power
Goodwill [Roll Forward]
BALANCE DECEMBER 31, 2018	1,070.3
Foreign currency translation	0.7
BALANCE MARCH 31, 2019	$ 1,071.0