Income Taxes - Components of Income Tax (Expense) Benefit (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current Expense:
U.S.	$ (1.1)	$ (1.6)	$ (15.9)
International	(13.5)	(15.7)	(9.2)
Total Current	(14.6)	(17.3)	(25.1)
Deferred (Expense) Benefit:
U.S.	(0.8)	(0.1)	343.8
International	(5.0)	5.6	3.0
Total Deferred	(5.8)	5.5	346.8
Income Tax (Expense) Benefit	$ (20.4)	$ (11.8)	$ 321.7