Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Unpaid Principal (Details) - Variable Interest Entity, Primary Beneficiary - Financial Guaranty Variable Interest Entities - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
FG VIEs’ assets	$ 264	$ 255
FG VIEs’ liabilities with recourse	30	12
FG VIEs’ liabilities without recourse	15	15
Unpaid principal balance for FG VIEs’ assets that were 90 days or more past due	43	52
Unpaid principal for FG VIEs’ liabilities with recourse	$ 297	$ 281