Income Taxes - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Current	$ 6.7	$ 2.3	$ (3.1)
Deferred	(1.6)	61.6	(38.9)
Income tax expense (benefit)	$ 5.1	$ 63.9	$ (42.0)