Income Taxes - Schedule of Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Federal
Current	$ 0.1	$ 0.1	$ 0.1
Deferred taxes and other accruals	31.2	22.8	12.5
State	6.6	3.7	2.0
Total provision (benefit) for income taxes	$ 37.9	$ 26.6	$ 14.6