Income Taxes - Income Tax Provision (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
U.S. federal	$ (23.9)	$ (21.5)	$ (46.8)
Non-U.S.	2.4	28.4	29.8
State	1.7	(0.3)	(0.1)
Total current	(19.8)	6.6	(17.1)
Deferred:
U.S. federal	23.4	20.3	30.4
Non-U.S.	4.4	19.3	5.7
State	0.0	(0.2)	(0.6)
Total deferred	27.8	39.4	35.5
Total income tax provision	$ 8.0	$ 46.0	$ 18.4