Business Acquisitions - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($) acquisition	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 1,058.7		$ 1,058.7		$ 991.0
Cash used for acquisitions			108.5	$ 171.6
Power
Business Acquisition [Line Items]
Number of businesses acquired | acquisition		2
Consideration transferred		$ 9.5
Intangible assets		3.4
Goodwill	346.2	$ 4.7	346.2		$ 339.0
Intangible assets, useful life		13 years
Tax deductible goodwill		$ 2.7
iDevices
Business Acquisition [Line Items]
Consideration transferred	59.2
Intangible assets	9.6		9.6
Goodwill	$ 45.4		45.4
Intangible assets, useful life	12 years
AEC
Business Acquisition [Line Items]
Consideration transferred	$ 31.5
Intangible assets	18.5		18.5
Goodwill	$ 10.0		$ 10.0
Intangible assets, useful life	22 years