Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Number of Consolidated CIVs by Type (Details) - Variable Interest Entity, Primary Beneficiary	Sep. 30, 2022 Entity	Sep. 30, 2022 consolidatedInvestmentFund	Sep. 30, 2022 consolidatedCLO	Sep. 30, 2022 cLOWarehouse	Sep. 30, 2022 consolidatedInvestmentVehicle	Dec. 31, 2021 Entity	Dec. 31, 2021 consolidatedInvestmentFund	Dec. 31, 2021 consolidatedCLO	Dec. 31, 2021 cLOWarehouse	Dec. 31, 2021 consolidatedInvestmentVehicle	Sep. 30, 2021 Entity	Dec. 31, 2020 Entity
Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Total number of entities consolidated	22				22	20				20	16	11
Consolidated Investment Vehicles | Investment Managed Funds
Variable Interest Entity [Line Items]
Total number of entities consolidated | consolidatedInvestmentFund		8					8
Consolidated Investment Vehicles | Collateralized Loan Obligations
Variable Interest Entity [Line Items]
Total number of entities consolidated | consolidatedCLO			10					9
Consolidated Investment Vehicles | Collateralized Loan Obligation Warehouses
Variable Interest Entity [Line Items]
Total number of entities consolidated | cLOWarehouse				4					3
Consolidated Investment Vehicles, Meeting Voting Interest Entity Criteria
Variable Interest Entity [Line Items]
Total number of entities consolidated | consolidatedInvestmentVehicle					2					1