SEC Schedule, Article 12-16, Supplementary Insurance Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Liability for Claims and Claims Adjustment Expense	$ 893	$ 805
Deferred Policy Acquisition Cost	11	3
Unearned premiums	422	372
Premiums Earned, Net	78	56	$ 47
Net Investment Income	140	17	139
Policyholder Benefits and Claims Incurred, Net	(33)
Deferred Policy Acquisition Costs, Amortization Expense	11	3	1
General and Administrative Expense	156	141	111
Premiums Written, Net	44	23	(33)
Legacy Financial Guarantee
Liability for Claims and Claims Adjustment Expense	696	715	1,538
Deferred Policy Acquisition Cost	0	0	0
Unearned premiums	267	287	385
Premiums Earned, Net	26	42	46
Net Investment Income	127	12	138
Policyholder Benefits and Claims Incurred, Net	(69)	(406)	(89)
Deferred Policy Acquisition Costs, Amortization Expense	0	0	0
General and Administrative Expense	108	104	77
Premiums Written, Net	(35)	(6)	(35)
Specialty Property & Casualty Program [Domain]
Liability for Claims and Claims Adjustment Expense	197	90	32
Deferred Policy Acquisition Cost	11	3	0
Unearned premiums	155	85	10
Premiums Earned, Net	52	14	1
Net Investment Income	4	2	1
Policyholder Benefits and Claims Incurred, Net	37	9	0
Deferred Policy Acquisition Costs, Amortization Expense	11	3	0
General and Administrative Expense	16	13	9
Premiums Written, Net	$ 80	$ 29	$ 13