Financial Guarantee Insurance Contracts Financial Guarantee Insurance Contracts - Components of Loss and Loss Expense Reserves and Subrogation Recoverable (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Policyholder Benefits and Claims Incurred, Ceded	$ 41	$ (5)	$ 7
Liability for Unpaid Claims and Claims Adjustment Expense, Net	883	(578)	(430)	$ (508)
Subrogation recoverable	(271)	(2,092)
Claim liability reported on Balance Sheet, before reinsurance		(554)
Liability for Claims and Claims Adjustment Expense	805	1,570
Liabillity for Claim and Claim Adjustment Expense, with Impact of VIE Consolidation	534	(522)	(397)	$ (482)
Premiums Earned, Net	56	47	$ 54
Legacy Financial Guarantee
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Premiums Earned, Net	42	46
Property and Casualty, Commercial Insurance
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Liability for Claims and Claims Adjustment Expense	90	32
Premiums Earned, Net	14	1
Property and Casualty, Commercial Insurance
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Liability for Claims and Claims Adjustment Expense	90	32
Liabillity for Claim and Claim Adjustment Expense, with Impact of VIE Consolidation	90	32
Unearned Premium Reserve [Member]
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Subrogation recoverable	0	0
Claim liability reported on Balance Sheet, before reinsurance	(28)	(56)
Liability for Claims and Claims Adjustment Expense	(28)	(56)
Present Value of Expected Net Cash Flows- Claims and Loss Expenses [Member]
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Subrogation recoverable	5	88
Claim liability reported on Balance Sheet, before reinsurance	791	1,837
Liability for Claims and Claims Adjustment Expense	787	1,749
Present Value of Expected Net Cash Flows-Recoveries [Member]
Components of Loss and Loss Expense Reserves and Subrogation Recoverable [Line Items]
Subrogation recoverable	(276)	(2,180)
Claim liability reported on Balance Sheet, before reinsurance	(319)	(2,335)
Liability for Claims and Claims Adjustment Expense	$ (44)	$ (155)