Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Schedule of Assets and Liabilities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Assets	$ 16,852	$ 16,843
Liabilities	11,397	11,551
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities	4,460	4,625
Variable Interest Entity, Primary Beneficiary | Warehouse financing debt | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities	157	313
Variable Interest Entity, Primary Beneficiary | Due to brokers and counterparties | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities	60	112
Variable Interest Entity, Primary Beneficiary | Other liabilities | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities	105	110
Variable Interest Entity, Primary Beneficiary | CLO obligations of CFEs | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities	4,138	4,090
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Assets	5,055	5,493
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Fund investments: | Equity securities and warrants
Variable Interest Entity [Line Items]
Assets	299	434
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Fund investments: | Corporate securities
Variable Interest Entity [Line Items]
Assets	84	96
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Fund investments: | Structured products
Variable Interest Entity [Line Items]
Assets	74	128
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | CLOs and CLO warehouse assets: | Loans in CLOs, FVO
Variable Interest Entity [Line Items]
Assets	4,283	4,202
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | CLOs and CLO warehouse assets: | Loans in CLO warehouses, FVO
Variable Interest Entity [Line Items]
Assets	169	368
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | CLOs and CLO warehouse assets: | Short-term investments
Variable Interest Entity [Line Items]
Assets	69	135
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Investments in AssuredIM Funds and Other Affiliated Entities
Variable Interest Entity [Line Items]
Assets	267	392
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Cash and cash equivalents | Fund investments:
Variable Interest Entity [Line Items]
Assets	28	59
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Cash and cash equivalents | CLOs and CLO warehouse assets:
Variable Interest Entity [Line Items]
Assets	21	38
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Due from brokers and counterparties | Fund investments:
Variable Interest Entity [Line Items]
Assets	3	0
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Due from brokers and counterparties | CLOs and CLO warehouse assets:
Variable Interest Entity [Line Items]
Assets	25	32
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Other | Fund investments:
Variable Interest Entity [Line Items]
Assets	$ 0	$ 1
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | Warehouse financing debt
Variable Interest Entity [Line Items]
CLO's weighted average maturity	3 months 18 days	1 year 10 months 24 days
CLO's weighted average interest rate	5.30%	4.50%
Variable Interest Entity, Primary Beneficiary | Consolidated Investment Vehicles | CLO obligations of CFEs
Variable Interest Entity [Line Items]
CLO's weighted average maturity	5 years 9 months 18 days	6 years 2 months 12 days
CLO's weighted average interest rate	6.60%	5.30%
Voting Interest Entity | Consolidated Investment Vehicles
Variable Interest Entity [Line Items]
Liabilities		$ 1
Voting Interest Entity | Consolidated Investment Vehicles | Investments
Variable Interest Entity [Line Items]
Assets	$ 24	$ 58