Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended			9 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020		Jun. 30, 2021	Jun. 30, 2020		Sep. 30, 2020	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate (as a percent)	(509.10%)			13.60%		(78.80%)	50.20%
Provision (benefit) for income taxes	$ 43.0	$ (1.4)	$ (9.1)	$ (27.7)	[1]	$ 33.2	$ (101.9)	[1]	$ (111.0)	$ (112.4)
Loss before benefit for income taxes and equity in net income of affiliates	$ 8.5	$ (1.2)	$ 24.0	$ 203.0	[1]	$ 42.2	203.6	[1]	$ 227.6	$ 226.4
Income tax expense (benefit), CARES Act							$ (53.7)

[1] See discussion in Note 1 - Basis of Presentation for further detail regarding the elimination of the International lag reporting.