Goodwill and Other Assets Schedule of Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,058.7	$ 1,074.2
Accumulated amortization	(387.1)	(300.4)
Net carrying amount	$ 671.6	773.8
Internally-developed software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year 10 months
Gross carrying amount	$ 208.5	192.9
Accumulated amortization	(122.1)	(99.8)
Net carrying amount	$ 86.4	93.1
Development costs non-software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	5 months
Gross carrying amount	$ 53.2	55.3
Accumulated amortization	(43.2)	(35.1)
Net carrying amount	$ 10.0	20.2
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 11 months
Gross carrying amount	$ 722.2	741.5
Accumulated amortization	(162.5)	(108.2)
Net carrying amount	$ 559.7	633.3
Other intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 months
Gross carrying amount	$ 74.8	84.5
Accumulated amortization	(59.3)	(57.3)
Net carrying amount	15.5	27.2
Other intangible asset, net [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	336.5	332.7
Accumulated amortization	(224.6)	(192.2)
Net carrying amount	$ 111.9	$ 140.5