Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Additional Information (Details)		3 Months Ended		9 Months Ended
	Jul. 01, 2023 rISK	Sep. 30, 2023 USD ($) policy Entity Security entity consolidatedInvestmentVehicle	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) policy Entity Security entity consolidatedInvestmentVehicle	Sep. 30, 2022 USD ($)	Aug. 31, 2023 USD ($)	Dec. 31, 2022 USD ($) consolidatedInvestmentVehicle Security policy Entity entity
Variable Interest Entity [Line Items]
Estimated Fair Value		$ 6,267,000,000		$ 6,267,000,000			$ 7,119,000,000
Amortized Cost		6,971,000,000		6,971,000,000			7,707,000,000
Fixed-maturity securities, trading		350,000,000		350,000,000			303,000,000
Gross Unrealized Gains		30,000,000		30,000,000			65,000,000
Gross unrealized losses		$ 648,000,000		$ 648,000,000			$ 588,000,000
Number of securities | Security		1,308		1,308			466
Fair Value		$ 3,150,000,000		$ 3,150,000,000			$ 1,017,000,000
Number of securities | Security		795		795			1,340
Fair Value		$ 2,093,000,000		$ 2,093,000,000			$ 3,751,000,000
Fair value gains (losses) on credit derivatives		9,000,000	$ (48,000,000)	115,000,000	$ (42,000,000)
Other consolidated VIE assets		87,000,000		87,000,000			86,000,000
Other consolidated VIE liabilities		$ 7,000,000		$ 7,000,000			$ 12,000,000
Number of policies monitored | policy		15,000		15,000
Number of policies monitored, not within the scope of ASC 810 | policy		14,000		14,000
Number of policies that contain provisions for consolidation | policy		66		66			85
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt		$ 251,000,000		$ 251,000,000
Net		241,833,000,000		241,833,000,000		$ 108,000,000	$ 233,258,000,000
Carrying value of investments not consolidated		239,000,000		239,000,000
Other assets		12,000,000		12,000,000
Sound Point Agreement
Variable Interest Entity [Line Items]
Deconsolidated assets		4,700,000,000		4,700,000,000
Deconsolidated liabilities		4,400,000,000		4,400,000,000
Loss on deconsolidation		16,000,000		16,000,000
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Maximum loss exposure		0		0
Gain (loss) in the instrument specific credit risk of the VIEs' assets		$ 3,000,000	$ 15,000,000	$ 1,000,000	11,000,000
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary | Puerto Rico Trusts
Variable Interest Entity [Line Items]
Total number of entities consolidated | entity		24		24			45
Estimated Fair Value		$ 146,000,000		$ 146,000,000		$ 73,000,000	$ 204,000,000
Amortized Cost		136,000,000		136,000,000			204,000,000
Gross Unrealized Gains		10,000,000		10,000,000			4,000,000
Gross unrealized losses		$ 0		$ 0			$ 4,000,000
Number of securities | Security		0		0
Number of securities | Security							14
Fair Value							$ 110,000,000
Securities in excess of carrying value | Security							8
Unrealized losses for securities							$ 3,000,000
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary | Structured Finance and Other
Variable Interest Entity [Line Items]
Total number of entities consolidated | Entity		25		25			25
Puerto Rico Trusts | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Custody receipts, notice period		30 days		30 days
Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Number of remaining CIVs | rISK	3
Consolidated Investment Vehicles | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Total number of entities consolidated | consolidatedInvestmentVehicle		3		3			22
Collateral posting requirement		$ 36,000,000		$ 36,000,000			$ 46,000,000
Fair value gains (losses) on credit derivatives					$ 7,000,000
Consolidated Investment Vehicles | Voting Interest Entity
Variable Interest Entity [Line Items]
Total number of entities consolidated | consolidatedInvestmentVehicle							2
Consolidated Investment Vehicles | Maximum | Future Equity Investments
Variable Interest Entity [Line Items]
Committed capital				143,000,000
Consolidated Investment Vehicles | Average | Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Collateral posting requirement		$ 41,000,000		$ 41,000,000			$ 47,000,000