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Financial Guaranty Variable Interest Entities and Consolidated Investment Vehicles - Additional Information (Details) | 3 Months Ended |
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Mar. 31, 2023 USD ($) entity policy consolidatedInvestmentVehicle Security Entity | Mar. 31, 2022 USD ($) | Dec. 31, 2022 USD ($) consolidatedInvestmentVehicle Security entity Entity policy
Variable Interest Entity [Line Items] |  |  |
Estimated Fair Value | $ 6,869,000,000 |  | $ 7,119,000,000
Amortized Cost | 7,359,000,000 |  | 7,707,000,000
Fixed-maturity securities, trading | 300,000,000 |  | 303,000,000
Gross Unrealized Gains | 75,000,000 |  | 65,000,000
Gross Unrealized Losses | $ 496,000,000 |  | $ 588,000,000
Number of securities | Security | 1,006 |  | 466
Number of securities | Security | 602 |  | 1,340
Fair Value | $ 2,499,000,000 |  | $ 1,017,000,000
Fair Value | 1,584,000,000 |  | 3,751,000,000
Fair value gains (losses) on credit derivatives | 15,000,000 | $ (3,000,000) |
Other consolidated VIE assets | 89,000,000 |  | 86,000,000
Other consolidated VIE liabilities | $ 10,000,000 |  | $ 12,000,000
Number of policies monitored | policy | 15,000 |  |
Number of policies monitored, not within the scope of ASC 810 | policy | 14,000 |  |
Number of policies that contain provisions for consolidation | policy | 86 |  | 85
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt | $ 1,000,000 |  | $ 1,000,000
Joint Healthcare Fund | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Maximum borrowing capacity | 110,000,000 |  |
Long-term line of credit | 28,000,000 |  |
Consolidated Healthcare Fund | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Maximum borrowing capacity | $ 71,000,000 |  |
Prime Rate | Joint Healthcare Fund | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Base interest rate floor | 3.00% |  |
EURIBOR | Joint Healthcare Fund | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Base interest rate floor | 0.00% |  |
CLOs and CLO warehouse assets: |  |  |
Variable Interest Entity [Line Items] |  |  |
Fair Value | $ 377,000,000 |  | 250,000,000
Fair Value | 42,000,000 |  | $ 171,000,000
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary |  |  |
Variable Interest Entity [Line Items] |  |  |
Maximum loss exposure | 0 |  |
Change in the instrument specific credit risk of the VIEs' assets | $ 1,000,000 | 5,000,000 |
Financial Guaranty Variable Interest Entities | Variable Interest Entity, Primary Beneficiary | Puerto Rico Trusts |  |  |
Variable Interest Entity [Line Items] |  |  |
Total number of entities consolidated | entity | 45 |  | 45
Estimated Fair Value | $ 211,000,000 |  | $ 204,000,000
Amortized Cost | 204,000,000 |  | 204,000,000
Fixed-maturity securities, trading | 5,000,000 |  | 5,000,000
Gross Unrealized Gains | 10,000,000 |  | 4,000,000
Gross Unrealized Losses | $ 3,000,000 |  | $ 4,000,000
Number of securities | Security | 12 |  |
Number of securities | Security |  |  | 14
Fair Value | $ 21,000,000 |  |
Fair Value |  |  | $ 110,000,000
Securities in excess of carrying value | Security | 6 |  | 8
Unrealized losses for securities | $ 2,000,000 |  | $ 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
Puerto Rico Trusts | Variable Interest Entity, Primary Beneficiary |  |  |
Variable Interest Entity [Line Items] |  |  |
Custody receipts, notice period | 30 days |  |
Consolidated Investment Vehicles | Variable Interest Entity, Primary Beneficiary |  |  |
Variable Interest Entity [Line Items] |  |  |
Total number of entities consolidated | consolidatedInvestmentVehicle | 21 |  | 22
Collateral posting requirement | $ 39,000,000 |  | $ 46,000,000
Fair value gains (losses) on credit derivatives |  | $ 4,000,000 |
Consolidated Investment Vehicles | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Maximum borrowing capacity | 1,600,000,000 |  |
Remaining borrowing capacity | 252,000,000 |  |
Borrowing (payment) under credit facilities | $ 138,000,000 |  |
Consolidated Investment Vehicles | Voting Interest Entity |  |  |
Variable Interest Entity [Line Items] |  |  |
Total number of entities consolidated | consolidatedInvestmentVehicle | 1 |  | 2
Consolidated Investment Vehicles | EURIBOR | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Basis spread on variable rate | 2.50% |  |
Consolidated Investment Vehicles | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Variable Interest Entity, Primary Beneficiary | Line of Credit |  |  |
Variable Interest Entity [Line Items] |  |  |
Basis spread on variable rate | 1.50% |  |
Consolidated Investment Vehicles | Maximum | Future Equity Investments |  |  |
Variable Interest Entity [Line Items] |  |  |
Committed capital | $ 453,000,000 |  |
Consolidated Investment Vehicles | Average | Variable Interest Entity, Primary Beneficiary |  |  |
Variable Interest Entity [Line Items] |  |  |
Collateral posting requirement | $ 43,000,000 |  | $ 47,000,000
Consolidated Investment Vehicles | Fund investments: | Variable Interest Entity, Primary Beneficiary | Investments |  |  |
Variable Interest Entity [Line Items] |  |  |
Net assets |  |  | $ 127,000,000

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- Definition Amount of maximum exposure to loss from involvement with consolidated variable interest entity (VIE). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=123419778&loc=SL6759159-111685 + Details
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