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v2.4.1.9

Financial Guarantee Insurance Contracts - Summary of Information Related to Policies Currently Included in Ambac's Loss Reserves or Subrogation Recoverable (Detail) (Successor [Member], USD $) In Thousands, unless otherwise specified | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 Policies | Dec. 31, 2013 Policies | Apr. 30, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 325 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding | 339 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding |  |  |
Remaining weighted-average contract period (in years) | 16 years | 14 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | $ 18,322,914 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal | $ 22,206,789 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal |  |  |
Interest | 7,254,995 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest | 8,397,133 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest |  |  |
Total | 25,577,909 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding | 30,603,922 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding |  |  |
Gross undiscounted claim liability | 8,679,974 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability | 11,276,259 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability |  |  |
Discount, gross claim liability | 1,509,948 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability | 2,452,448 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability |  |  |
Gross claim liability before all subrogation and before reinsurance | 7,170,026 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability | 8,823,811 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | (2,541,219)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation | (2,215,849)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation |  |  |
Discount, RMBS subrogation | 17,679 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation | 9,251 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation |  |  |
Discounted RMBS subrogation, before reinsurance | (2,523,540)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,206,598)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,482,918)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,523,225)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,720,266)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation
Less: |  |  |  |  |
Gross other subrogation | (792,287)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation | (846,699)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation |  |  |
Discount, other subrogation | 91,808 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation | 91,313 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation |  |  |
Discounted other subrogation, before reinsurance | (700,479)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation | (755,386)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 3,946,007 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability | 5,861,827 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability |  |  |
Less: Unearned premium reserves | (241,348)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue | (502,984)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue |  |  |
Plus: Loss adjustment expenses reserves | 94,074 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve | 111,391 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 3,798,733 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability | 5,470,234 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability |  |  |
Reinsurance recoverable reported on Balance Sheet | 99,838 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable | 121,249 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable |  |  |
I/SL [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 36 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 18 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 8 years | 13 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 1,026,513 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 834,708 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 418,746 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 506,903 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 1,445,259 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,341,611 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 16,360 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 7,447 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 1,147 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,225 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 15,213 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,222 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 15,213 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,222 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | (10,945)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (4,060)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 3 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 4,271 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,162 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | 73 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 146 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
IA [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 26 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 23 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 12 years | 19 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 519,291 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,125,284 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 212,296 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 871,751 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 731,587 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,997,035 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 11,525 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 54,398 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 937 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,726 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 10,588 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 47,672 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 10,588 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 47,672 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | (3,432)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (22,901)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 1,303 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 8,459 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 24,782 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | 890 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,271 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
II [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 33 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 52 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 15 years | 17 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 3,091,744 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,464,420 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 1,878,770 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,130,271 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 4,970,514 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 5,594,691 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 155,488 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 221,321 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 16,438 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 32,630 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 139,050 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 188,691 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | (18,034)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (20,367)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 6,069 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 9,522 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | (11,965)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (10,845)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 127,085 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 177,846 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | (73,749)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (95,550)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 1,968 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,257 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 55,304 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 84,553 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | 1,355 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,273 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
III [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 69 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 76 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 21 years | 19 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 3,792,559 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 5,597,387 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 2,765,537 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,331,222 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 6,558,096 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 7,928,609 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 2,040,402 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,029,891 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 716,812 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,299,032 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 1,323,590 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,730,859 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (4,516)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 15 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (4,501)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | (127,143)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (116,145)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 36,779 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 36,125 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | (90,364)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (80,020)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 1,233,226 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,646,338 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | (88,332)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (280,245)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 6,470 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,658 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 1,151,364 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,367,751 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | 110,957 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 119,795 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
IV [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 160 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 169 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 12 years | 11 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 9,892,760 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11,184,943 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 1,979,627 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,556,968 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 11,872,387 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 13,741,911 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 6,456,139 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 7,963,137 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 774,611 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,112,829 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 5,681,528 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,850,308 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | (2,541,219)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (2,211,333)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 17,679 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 9,236 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | (2,523,540)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (2,202,097)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | (647,110)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (710,187)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 48,960 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 45,666 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | (598,150)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (664,521)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 2,559,838 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,983,690 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | (64,890)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (100,228)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 84,330 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 107,465 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 2,579,278 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,990,927 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | (13,437)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (3,236)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
V [Member] |  |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |  |
Number of policies | 1 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Remaining weighted-average contract period (in years) | 6 years | 6 years |  |  |
Gross insured contractual payments outstanding: |  |  |  |  |
Principal | 47 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 47 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Interest | 19 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 18 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Total | 66 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 65 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross undiscounted claim liability | 60 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 65 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, gross claim liability | 3 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability before all subrogation and before reinsurance | 57 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 59 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, RMBS subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted RMBS subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: |  |  |  |  |
Gross other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discount, other subrogation | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Discounted other subrogation, before reinsurance | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 57 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 59 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Less: Unearned premium reserves | 0 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Plus: Loss adjustment expenses reserves | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Claim liability reported on Balance Sheet, before reinsurance | 57 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 59 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Reinsurance recoverable reported on Balance Sheet | $ 0 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | $ 0 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |

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- Definition This element represents the discounting on the gross claim liability for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References No definition available. + Details
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- Definition This element represents the gross undiscounted claim liability for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References No definition available. + Details
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- Definition This element represents the amount of loss adjustment expense reserves represent the costs estimated to be incurred in the settlement of unpaid claims related to financial guarantee insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References No definition available. + Details
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- Definition This element represents the discount on the gross subrogation on insured financial obligations with credit deterioration, excluding the discount on the gross subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition This element represents the discounting on the reduction to gross claim liability for subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition This element represents the reduction to gross claim liability for subrogation on insured financial obligations with credit deterioration, excluding the reduction to gross claim liability for subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition This element represents the reduction to gross claim liability for subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition This element represents the reduction to gross undiscounted claim liability for gross undiscounted subrogation on insured financial obligations with credit deterioration, excluding subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition This element represents the reduction to gross undiscounted claim liability for gross undiscounted subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
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- Definition Remaining weighted average contract period of financial guarantee insurance contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(ii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 + Details
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X
- Definition This element represents the gross claim liability for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(iv) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the amount of insured contractual payments outstanding on the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(iii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the amount of insured contractual payments outstanding attributable to interest accrued on the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(iii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the amount of insured contractual payments outstanding attributable to the principal of the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(iii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the net claim liability related to financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(vii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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Balance Type: | credit
Period Type: | instant

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- Definition This element represents the number of issued and outstanding contracts for each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(i) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the claim liability, reported on or included in the statement of financial position, related to financial guarantee insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 34 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751140-161288 + Details
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- Definition This element represents the amount of reinsurance recoverable, reported on or included in the statement of financial position, related to financial guarantee insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(viii) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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- Definition This element represents the amount of unearned premium revenue, reported on or included in the statement of financial position, related to financial guarantee insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 55 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=34726416&loc=SL5751133-161288 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 9 -Subparagraph (a)(5)(ix) -URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292 + Details
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