Goodwill and Intangible Assets - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets
Gross Carrying Amount	$ 1,366.9	$ 1,316.5
Accumulated Amortization	(471.9)	(441.7)
Net Book Value	895.0	874.8
Customer lists
Finite-Lived Intangible Assets
Gross Carrying Amount	931.4	927.8
Accumulated Amortization	(301.9)	(283.2)
Net Book Value	629.5	644.6
Developed technology
Finite-Lived Intangible Assets
Gross Carrying Amount	382.8	381.3
Accumulated Amortization	(166.2)	(155.6)
Net Book Value	216.6	225.7
Tradenames
Finite-Lived Intangible Assets
Gross Carrying Amount	51.1	5.9
Accumulated Amortization	(2.4)	(1.6)
Net Book Value	48.7	4.3
Non-compete agreements
Finite-Lived Intangible Assets
Gross Carrying Amount	1.6	1.5
Accumulated Amortization	(1.4)	(1.3)
Net Book Value	$ 0.2	$ 0.2