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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 | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2015 Policies | Dec. 31, 2014 Policies | Mar. 31, 2014 | Dec. 31, 2013
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |
Number of policies | 330 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding | 325 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding |  |
Remaining weighted-average contract period (in years) | 15 years | 16 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | $ 18,482,283 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal | $ 18,322,914 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal |  |
Interest | 13,218,716 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest | 7,254,995 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest |  |
Total | 31,700,999 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding | 25,577,909 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding |  |
Gross undiscounted claim liability | 8,232,073 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability | 8,679,974 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability |  |
Discount, gross claim liability | 1,260,130 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability | 1,509,948 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability |  |
Gross claim liability before all subrogation and before reinsurance | 6,971,943 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability | 7,170,026 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability |  |
Less: |  |  |  |
Gross RMBS subrogation | (2,579,450)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation | (2,541,219)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation |  |
Discount, RMBS subrogation | 11,097 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation | 17,679 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation |  |
Discounted RMBS subrogation, before reinsurance | (2,568,353)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,523,540)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,224,295)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation | (2,206,598)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation
Less: |  |  |  |
Gross other subrogation | (815,033)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation | (792,287)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation |  |
Discount, other subrogation | 76,537 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation | 91,808 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation |  |
Discounted other subrogation, before reinsurance | (738,496)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation | (700,479)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 3,665,094 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability | 3,946,007 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability |  |
Less: Unearned premium reserves | (258,765)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue | (241,348)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue |  |
Plus: Loss adjustment expenses reserves | 85,533 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve | 94,074 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve |  |
Claim liability reported on Balance Sheet, before reinsurance | 3,491,862 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability | 3,798,733 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability |  |
Reinsurance recoverable reported on Balance Sheet | 79,308 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable | 99,838 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable |  |
I/SL [Member] |  |  |  |
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items] |  |  |  |
Number of policies | 34 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 36 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Remaining weighted-average contract period (in years) | 7 years | 8 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | 910,033 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,026,513 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Interest | 339,721 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 418,746 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 1,249,754 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,445,259 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 12,901 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16,360 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 644 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,147 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 12,257 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 15,213 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 | 12,257 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 15,213 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (8,812)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (10,945)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Plus: Loss adjustment expenses reserves | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Claim liability reported on Balance Sheet, before reinsurance | 3,445 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 4,271 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Reinsurance recoverable reported on Balance Sheet | 1 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneSurveyListMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 73 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 | 21 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 26 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Remaining weighted-average contract period (in years) | 16 years | 12 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | 399,516 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 519,291 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Interest | 159,138 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 212,296 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 558,654 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 731,587 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 6,344 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11,525 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 605 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 937 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 5,739 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 10,588 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 | 5,739 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 10,588 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (2,175)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (3,432)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Plus: Loss adjustment expenses reserves | 16 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,303 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Claim liability reported on Balance Sheet, before reinsurance | 3,580 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 8,459 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Reinsurance recoverable reported on Balance Sheet | 910 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryOneaMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 890 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 | 43 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 33 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Remaining weighted-average contract period (in years) | 17 years | 15 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | 4,186,210 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,091,744 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Interest | 8,484,779 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,878,770 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 12,670,989 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 4,970,514 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 239,113 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 155,488 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 18,502 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 16,438 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 220,611 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 139,050 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 | (12,388)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (18,034)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, other subrogation | 3,474 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,069 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discounted other subrogation, before reinsurance | (8,914)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (11,965)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 211,697 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 127,085 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (107,836)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (73,749)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Plus: Loss adjustment expenses reserves | 2,185 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,968 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Claim liability reported on Balance Sheet, before reinsurance | 106,046 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 55,304 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Reinsurance recoverable reported on Balance Sheet | 2,331 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryTwoMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,355 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 | 66 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 69 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Remaining weighted-average contract period (in years) | 21 years | 21 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | 3,550,121 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3,792,559 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Interest | 2,286,780 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,765,537 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 5,836,901 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,558,096 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 1,596,918 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,040,402 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 521,225 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 716,812 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 1,075,693 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,323,590 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 | 0 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 | 0 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 | 0 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: |  |  |  |
Gross other subrogation | (142,548)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (127,143)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, other subrogation | 35,608 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 36,779 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discounted other subrogation, before reinsurance | (106,940)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (90,364)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 968,753 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,233,226 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (76,061)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (88,332)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Plus: Loss adjustment expenses reserves | 7,465 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,470 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Claim liability reported on Balance Sheet, before reinsurance | 900,157 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,151,364 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Reinsurance recoverable reported on Balance Sheet | 85,082 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryThreeMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 110,957 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 | 163 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 160 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Remaining weighted-average contract period (in years) | 13 years | 12 years |  |
Gross insured contractual payments outstanding: |  |  |  |
Principal | 9,376,691 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 9,892,760 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Interest | 1,928,647 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 1,979,627 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 11,305,338 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 11,872,387 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 6,297,440 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 6,456,139 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 712,562 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 774,611 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 5,584,878 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 5,681,528 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: |  |  |  |
Gross RMBS subrogation | (2,579,450)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (2,541,219)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, RMBS subrogation | 11,097 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 17,679 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discounted RMBS subrogation, before reinsurance | (2,568,353)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (2,523,540)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: |  |  |  |
Gross other subrogation | (646,741)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (647,110)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, other subrogation | 33,795 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 48,960 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityDiscountOnOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discounted other subrogation, before reinsurance | (612,946)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (598,150)ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityOtherSubrogation / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability, net of all subrogation and discounts, before reinsurance | 2,403,579 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,559,838 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (63,368)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (64,890)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenue / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Plus: Loss adjustment expenses reserves | 75,825 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 84,330 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationLossAdjustmentExpensesReserve / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Claim liability reported on Balance Sheet, before reinsurance | 2,416,036 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 2,579,278 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Reinsurance recoverable reported on Balance Sheet | (9,016)us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionReinsuranceRecoverable / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFourMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | (13,437)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 | 3 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 | 59,712 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 | 19,651 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 19 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingInterest / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Total | 79,363 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 66 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstanding / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross undiscounted claim liability | 79,357 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 60 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Discount, gross claim liability | 6,592 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 3 ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationDiscountOnGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Gross claim liability before all subrogation and before reinsurance | 72,765 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 57 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 | (13,356)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 | 3,660 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 | (9,696)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 | 63,069 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 57 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |
Less: Unearned premium reserves | (513)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 | 42 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 | 62,598 us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionClaimLiability / us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis = ambc_SurveillanceCategoryFiveMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember | 57 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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- Details
Name: | ambc_DiscountedOtherSubrogationBeforeReinsuranceAbstract
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | ambc_LessDiscountedRmbsSubrogationBeforeReinsuranceAbstract
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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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Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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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
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossUndiscountedClaimLiability
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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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Namespace Prefix: | ambc_
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Balance Type: | credit
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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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Namespace Prefix: | ambc_
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Balance Type: | debit
Period Type: | instant

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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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Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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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Namespace Prefix: | ambc_
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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
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedOtherSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossUndiscountedClaimLiabilityGrossUndiscountedRmbsSubrogation
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Balance Type: | credit
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X
- 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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Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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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- 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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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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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Balance Type: | credit
Period Type: | instant

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- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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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Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- 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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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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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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
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- Details
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