Business and Significant Accounting Policies - Additional Information (Detail) $ in Millions	2 Months Ended	3 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2024 USD ($) segment	Nov. 15, 2023 USD ($)	Dec. 31, 2024 USD ($) segment trust	Dec. 31, 2022 USD ($) segment
Business And Significant Accounting Policies [Line Items]
Number of reportable segments | segment		3		3	2
Number of statutory trusts | trust				11
Investments reported at fair value for which we did not receive a fair value from a pricing service or broker (less than)		3.00%		3.00%
Amortization of intangible assets	$ 37.9		$ 0.0	$ 172.0	$ 0.0
Impairment of goodwill and intangibles	0.0		0.0	0.0	28.5
Impairment of indefinite lived intangible assets					17.3
Impairment of goodwill					11.2
Accumulated depreciation for property and equipment	2.3	$ 13.7		13.7
Net book value of property and equipment	31.1	$ 20.6		20.6
Depreciation expense	$ 2.3		$ 9.1	$ 11.4	$ 22.3
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets		Other assets
Foreign currency translation adjustment (loss) income	$ 0.1	$ (0.4)		$ (0.4)
Non-cash activity for a lease entered into				3.3
Private Loans | Related Party
Business And Significant Accounting Policies [Line Items]
Non-cash transaction, private loans		$ 300.0		$ 300.0
Minimum
Business And Significant Accounting Policies [Line Items]
Useful life		3 years		3 years
Derivative term of the contract				30 days
Maximum
Business And Significant Accounting Policies [Line Items]
Useful life		39 years		39 years
Derivative term of the contract				90 days