Goodwill and Other Assets Schedule of Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,038.7	$ 1,033.8
Accumulated amortization	(467.8)	(409.2)
Net carrying amount	$ 570.9	624.6
Internally-developed software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 7 months 6 days
Gross carrying amount	$ 199.1	189.6
Accumulated amortization	(133.9)	(118.9)
Net carrying amount	$ 65.2	70.7
Development costs non-software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	4 years
Gross carrying amount	$ 52.1	52.5
Accumulated amortization	(45.1)	(44.3)
Net carrying amount	$ 7.0	8.2
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 8 months 12 days
Gross carrying amount	$ 707.8	712.2
Accumulated amortization	(215.5)	(179.1)
Net carrying amount	$ 492.3	533.1
Other intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 6 months
Gross carrying amount	$ 79.7	79.5
Accumulated amortization	(73.3)	(66.9)
Net carrying amount	6.4	12.6
Other intangible asset, net [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	330.9	321.6
Accumulated amortization	(252.3)	(230.1)
Net carrying amount	$ 78.6	$ 91.5