Income Taxes - Income Tax Benefit (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current tax (expense) benefit
Federal		$ (16.1)
State		4.2	$ (1.6)	$ (1.9)
Total current tax		(11.9)	(1.6)	(1.9)
Deferred tax benefit (expense)
Federal		23.7	22.2	34.2
State		8.5	(6.8)	(1.7)
Total deferred tax		32.2	15.4	32.5
Income tax benefit, Continuing operations		20.3	13.8	30.6
Income tax benefit (expense)		$ 20.3	$ (292.9)	$ (7.8)
Refund received of remaining amount of refundable Alternative Minimum Tax carryforwards	$ 4.4