Goodwill and Intangible Assets - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,319.5	$ 1,352.8
Accumulated Amortization	(415.0)	(344.6)
Net Book Value	904.5	1,008.2
Customer lists
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	929.7	952.0
Accumulated Amortization	(266.3)	(222.5)
Net Book Value	663.4	729.5
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	382.3	393.0
Accumulated Amortization	(146.0)	(119.9)
Net Book Value	236.3	273.1
Tradenames
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5.9	6.1
Accumulated Amortization	(1.5)	(1.1)
Net Book Value	4.4	5.0
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1.6	1.7
Accumulated Amortization	(1.2)	(1.1)
Net Book Value	$ 0.4	$ 0.6