Income Taxes - Components of Income Before Tax and Benefit for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Valuation allowance	$ 245.2	$ 158.8
Components of income (loss) before income taxes
United States	(356.0)	(336.6)	$ (563.7)
Foreign	16.7	108.8	85.0
Net (loss) income before income taxes	(339.3)	(227.8)	(478.7)
Current
U.S. Federal	19.0	5.0	10.2
U.S. State	3.7	(4.0)	(0.3)
Foreign	22.6	24.8	32.0
Total	45.3	25.8	41.9
Deferred
U.S. Federal	(9.8)	(5.8)	(129.5)
U.S. State	(7.1)	2.5	(8.5)
Foreign	(15.3)	(8.0)	(28.9)
Total	(32.2)	(11.3)	(166.9)
Total income tax expense (benefit)	$ 13.1	$ 14.5	$ (125.0)