Goodwill and Other Assets Schedule of Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,059.0	$ 1,074.2
Accumulated amortization	(354.5)	(300.4)
Net carrying amount	$ 704.5	773.8
Internally-developed software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 1 month
Gross carrying amount	$ 203.3	192.9
Accumulated amortization	(113.0)	(99.8)
Net carrying amount	$ 90.3	93.1
Development costs non-software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 months
Gross carrying amount	$ 53.5	55.3
Accumulated amortization	(40.5)	(35.1)
Net carrying amount	$ 13.0	20.2
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	7 years 2 months
Gross carrying amount	$ 726.7	741.5
Accumulated amortization	(144.3)	(108.2)
Net carrying amount	$ 582.4	633.3
Other intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	1 year 2 months
Gross carrying amount	$ 75.5	84.5
Accumulated amortization	(56.7)	(57.3)
Net carrying amount	18.8	27.2
Other intangible asset, net [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	332.3	332.7
Accumulated amortization	(210.2)	(192.2)
Net carrying amount	$ 122.1	$ 140.5