Goodwill and Intangible Assets - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 3,466.0	$ 3,587.1
Accumulated Amortization	(935.8)	(835.6)
Net Book Value	2,530.2	2,751.5
Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,286.3	1,303.3
Accumulated Amortization	(297.5)	(263.5)
Net Book Value	988.8	1,039.8
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,147.3	2,250.7
Accumulated Amortization	(621.0)	(557.0)
Net Book Value	1,526.3	1,693.7
Tradenames
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	29.6	30.3
Accumulated Amortization	(15.8)	(13.8)
Net Book Value	13.8	16.5
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2.8	2.8
Accumulated Amortization	(1.5)	(1.3)
Net Book Value	$ 1.3	$ 1.5