Goodwill and Other Assets Schedule of Intangible Assets (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 1,001.1	$ 1,033.8
Accumulated amortization	(479.2)	(409.2)
Net carrying amount	$ 521.9	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	$ 196.4	189.6
Accumulated amortization	(136.7)	(118.9)
Net carrying amount	$ 59.7	70.7
Development costs non-software [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	3 years 1 month 6 days
Gross carrying amount	$ 50.2	52.5
Accumulated amortization	(44.8)	(44.3)
Net carrying amount	$ 5.4	8.2
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	6 years 4 months 24 days
Gross carrying amount	$ 677.3	712.2
Accumulated amortization	(225.3)	(179.1)
Net carrying amount	$ 452.0	533.1
Other intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years
Gross carrying amount	$ 77.2	79.5
Accumulated amortization	(72.4)	(66.9)
Net carrying amount	4.8	12.6
Other intangible asset, net [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	323.8	321.6
Accumulated amortization	(253.9)	(230.1)
Net carrying amount	$ 69.9	$ 91.5