XML 61 R59.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Fair Value Measurements - Summary of Changes in Level 3 Fair Value Category (Detail) (Successor [Member], USD $) In Thousands, unless otherwise specified | 3 Months Ended
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Mar. 31, 2015 | Mar. 31, 2014
Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | $ 198,201 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | $ 67,783 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 5,729 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 419 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (5,706)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (217)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 84,504 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (19,996)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (854)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three |  | (208)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 262,732 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 66,923 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Derivatives by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | (215,346)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (186,934)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (13,921)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (14,249)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (934)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (1,299)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | (230,201)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (202,482)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | 14,364 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 15,024 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Credit Derivative [Member] | Derivatives by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | (73,459)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (94,322)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (2,499)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 7,382 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (419)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (775)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | (76,377)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (87,715)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | 2,942 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (6,607)ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByLiabilityClassAxis = ambc_CreditDerivativeMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Interest Rate Swaps [Member] | Derivatives by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | (141,887)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (92,612)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (11,422)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (21,631)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (515)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (524)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | (153,824)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (114,767)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | 11,422 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 21,631 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByLiabilityClassAxis = us-gaap_InterestRateSwapMember / us-gaap_FinancialInstrumentAxis = us-gaap_DerivativeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Residential Mortgage-Backed Securities [Member] | Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 194,393 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 5,748 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (5,420)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 84,504 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (16,493)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 262,732 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Collateralized Debt Obligations [Member] | Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Asset-backed Securities [Member] | Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 64,073 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 443 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (295)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (854)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 63,367 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Corporate Obligations [Member] | Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 3,808 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,502 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (19)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (24)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (286)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 78 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (3,503)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Balance, end of period | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,556 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
US Government Agencies Debt Securities [Member] | Investment by Class [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 208 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three |  | (208)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FinancialInstrumentAxis = us-gaap_InvestmentTypeMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USGovernmentAgenciesDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Level 3 [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 13,845,454 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 14,253,705 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 354,562 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 172,538 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (631,215)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 86,799 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 84,504 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 70,000 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 148,979 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 173,451 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 208 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 13,504,326 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 14,409,383 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | (348,390)ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (169,349)ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | (215,346)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (186,934)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (13,921)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (14,249)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 934 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,299 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | (230,201)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (202,482)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | 14,364 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 15,024 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByLiabilityClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Level 3 [Member] | Investments [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 198,201 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 67,783 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | 5,729 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 419 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (5,706)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (217)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 84,504 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 19,996 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 854 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 208 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 262,732 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 66,923 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | 0 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByAssetClassAxis = us-gaap_InvestmentsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Level 3 [Member] | Other Assets [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance, beginning of period | 12,036 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 13,384 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Included in earnings | (295)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (262)ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityIssues / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 1,705 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
Balance, end of period | 10,036 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 13,122 ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date | $ 295 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | $ 262 ambc_FairValueAssetOrLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainsLossesStillHeld / us-gaap_FairValueByAssetClassAxis = us-gaap_OtherAssetsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember

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- Definition The amount of gains or losses included in earnings attributable to unrealized gains or losses on financial instruments measured on a recurring basis using unobservable inputs that are still held at the reporting date. + References No definition available. + Details
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- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset or liability. + References No definition available. + Details
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- Definition Amount of gain or loss included in earnings arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of gain or loss included in other comprehensive income arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of issuances related to financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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- Definition Amount of purchases of financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
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X
- Definition Amount of sales of financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySales
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of settlements related to financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilitySettlements
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of change in fair value of financial instruments measured on a recurring basis using unobservable inputs arising from transfers into level 3 of the fair value hierarchy. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersIntoLevelThree
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of change in fair value of financial instruments measured on a recurring basis using unobservable inputs arising from transfers out of level 3 of the fair value hierarchy. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityTransfersOutOfLevelThree
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |