Redeemable Noncontrolling Interests (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Redeemable Noncontrolling Interest [Abstract]
Document Period End Date	Sep. 30, 2018
Balance at January 1	$ 492.1	$ 44.1
Other comprehensive income	(17.2)	25.6
Redemption value adjustment	(12.1)	32.0
Redemption of shares	(308.6)	(2.7)
Reclassification of noncontrolling interest	0.0	386.7
Balance at September 30	$ 154.2	$ 485.7