Income Taxes - Income Tax (Benefit) Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
U.S.:
Federal	$ 14.9	$ (1.2)	$ 0.1
State and local	0.4	1.0	0.4
Foreign	63.2	65.7	0.6
Total current	78.5	65.5	1.1
U.S.:
Federal	(35.1)	(78.4)	(27.8)
State and local	(4.3)	(2.1)	(2.2)
Foreign	(15.3)	(53.6)	(12.4)
Total deferred	(54.7)	(134.1)	(42.4)
Income tax expense (benefit)	$ 23.8	$ (68.6)	$ (41.3)