Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Schedule of Assets and Liabilities of Consolidated Investment Vehicles (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Cash	$ 121	$ 97	$ 107
Fixed-maturity securities, available-for-sale	6,369	6,307
Total assets	11,901	12,539
Total liabilities	6,348	6,774
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles
Variable Interest Entity [Line Items]
Total liabilities	0	4
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles | Affiliated Entity
Variable Interest Entity [Line Items]
Total liabilities		3
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles
Variable Interest Entity [Line Items]
Total assets	101	366
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles | Affiliated Entity
Variable Interest Entity [Line Items]
Total assets	99	281
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles | Fund Investments
Variable Interest Entity [Line Items]
Cash	2	35
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles | Assets of CIVs, equity securities
Variable Interest Entity [Line Items]
Fixed-maturity securities, available-for-sale	99	83
Variable Interest Entity, Primary Beneficiary | Consolidated investment vehicles | Structured products
Variable Interest Entity [Line Items]
Fixed-maturity securities, available-for-sale	$ 0	$ 248