Income Taxes - Schedule of Income Tax (Benefit) Provision Expense (Detail) - USD ($) $ in Millions	2 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2023	Nov. 15, 2023	Dec. 31, 2024	Dec. 31, 2022
Current income tax provision (benefit) related to:
United States (Federal)	$ 4.2	$ 15.1	$ (0.2)	$ (21.0)
United States (State)	(4.2)	0.1	(0.2)	0.1
United Kingdom	0.0	(0.1)	0.0	(0.8)
Other jurisdictions	0.0	0.1	0.0	(1.7)
Total current income tax provision	0.0	15.2	(0.4)	(23.4)
Deferred income tax provision (benefit) related to:
United States	1.3	(7.9)	(41.8)	6.0
United Kingdom	0.0	(7.0)	0.0	7.3
Other jurisdictions	0.0	0.0	0.0	2.1
Total deferred income tax (benefit)	1.3	(14.9)	(41.8)	15.4
Income tax provision (benefit)	$ 1.3	$ 0.3	$ (42.2)	$ (8.0)