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v2.4.1.9

Background and Business Description - Additional Information (Detail) (USD $) | 9 Months Ended | 12 Months Ended | 1 Months Ended | 12 Months Ended | 8 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2014 | Dec. 31, 2014 Rate Segment | Dec. 31, 2013 | Apr. 30, 2013 | Dec. 31, 2010 | Dec. 31, 2013 | May 01, 2013
Background And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Unpaid as a Percentage of Permitted Policy Claims |  | 55.00%ambc_UnpaidasaPercentageofPermittedPolicyClaims |  |  |  |  |
Entity Incorporation, Date of Incorporation |  | Apr. 29, 1991 |  |  |  |  |
Number of reportable segments |  | 2 us-gaap_NumberOfReportableSegments |  |  |  |  |
Par Value of Owner Trust Certificate |  | $ 74,794,000 ambc_ParValueofOwnerTrustCertificate |  |  |  |  |
Par Value of Private Placement |  | 299,175,000 ambc_ParValueofPrivatePlacement |  |  |  |  |
Private Placement Par Value Proceeds |  | 80.00%ambc_PrivatePlacementParValueProceeds |  |  |  |  |
Private Placement Maturity Date |  | Aug. 28, 2039 |  |  |  |  |
Interest on junior surplus notes |  | 5.10%ambc_InterestRateonPrivatePlacementObligations |  |  |  |  |
Investment Warrants Expiration Date |  | Apr. 30, 2023 |  |  |  |  |
Transaction Limit |  | 5,000,000 ambc_TransactionLimit |  |  |  |  |
Accrued rate of interest on outstanding policy obligations (percent) |  | 5.10%ambc_DeferredAmountsandJuniorDeferredAmountsAccruedInterestRate |  |  |  |  |
Payment of permitted policy claim (percent) | 25.00%ambc_PaymentAsPercentageOfPermittedPolicyClaim | 25.00%ambc_PaymentAsPercentageOfPermittedPolicyClaim |  |  |  |  |
Equalizing payment on unpaid permitted policy claim (percent) |  | 26.67%ambc_EqualizingPaymentonUnpaidPermittedPolicyClaim |  |  |  |  |
December 2014 Payment of Deferred Amounts |  | 1,137,471,000 ambc_December2014PaymentofDeferredAmounts |  |  |  |  |
Capital Stock Authorized |  |  |  | 150,000,000 ambc_CapitalStockAuthorized |  |  |
Common stock, shares authorized |  | 130,000,000 us-gaap_CommonStockSharesAuthorized | 130,000,000 us-gaap_CommonStockSharesAuthorized | 130,000,000 us-gaap_CommonStockSharesAuthorized |  | 130,000,000 us-gaap_CommonStockSharesAuthorized |
Common Stock, Par or Stated Value Per Share |  | $ 0.01 us-gaap_CommonStockParOrStatedValuePerShare | $ 0.01 us-gaap_CommonStockParOrStatedValuePerShare | $ 0.01 us-gaap_CommonStockParOrStatedValuePerShare |  | $ 0.01 us-gaap_CommonStockParOrStatedValuePerShare |
Preferred stock, shares authorized |  | 20,000,000 us-gaap_PreferredStockSharesAuthorized | 20,000,000 us-gaap_PreferredStockSharesAuthorized | 20,000,000 us-gaap_PreferredStockSharesAuthorized |  | 20,000,000 us-gaap_PreferredStockSharesAuthorized |
Preferred Stock, Par or Stated Value Per Share |  | $ 0.01 us-gaap_PreferredStockParOrStatedValuePerShare | $ 0.01 us-gaap_PreferredStockParOrStatedValuePerShare | $ 0.01 us-gaap_PreferredStockParOrStatedValuePerShare |  | $ 0.01 us-gaap_PreferredStockParOrStatedValuePerShare |
Common stock, shares issued |  | 45,005,932 us-gaap_CommonStockSharesIssued | 45,003,461 us-gaap_CommonStockSharesIssued | 45,000,000 us-gaap_CommonStockSharesIssued |  | 45,003,461 us-gaap_CommonStockSharesIssued |
Warrants Distributed In Bankruptcy |  |  |  | 5,047,138 us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights |  |  |
Warrants issued exercise price |  |  |  | $ 16.67 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1 |  |  |
Mediation Agreement Cash Grant |  |  |  | 30,000,000 ambc_MediationAgreementCashGrant |  |  |
Junior surplus note of Ambac Assurance Segregated Account |  |  |  |  |  |  | 350,000,000 ambc_Ambc_JuniorSurplusNotesIssued
Common Stock Voting Restrictions |  | 10.00%ambc_CommonStockVotingRestrictions | 10.00%ambc_CommonStockVotingRestrictions |  |  |  |
Common Stock Voting Restriction Less One Vote |  | 10.00%ambc_CommonStockVotingRestrictionLessOneVote |  |  |  |  |
Common Stock Transfer Restrictions |  | 5.00%ambc_CommonStockTransferRestrictions |  |  |  |  |
Common Stock Additional Transfer Restrictions |  | 5.00%ambc_CommonStockAdditionalTransferRestrictions |  |  |  |  |
November 2014 Payment of Surplus Notes |  | 413,587,000 ambc_November2014PaymentofSurplusNotes |  |  |  |  |
Ambac Assurance [Member] |  |  |  |  |  |  |
Background And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Net par exposure for policies allocated to the Segregated Account |  | 18,808,470,000 ambc_NetParExposureForPoliciesAllocatedToSegregatedAccount / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |  |  |  |
Issuance of secured note to segregated account |  |  |  |  | 2,000,000,000 ambc_SecuredNoteIssued / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |
Secured note maturity year |  |  |  |  | 2050 |  |
Interest on the secured note accrues |  |  |  |  | 4.50%ambc_AccruedInterestRatePercentage / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |
Available secured notes including capitalized interest |  | 0 ambc_SecuredNoteOutstanding / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |  |  |  |
Minimum surplus amount |  | 100,000,000 ambc_MinimumSurplusAmount / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |  |  |  |
Maximum Reimbursement Of Operating Expenses |  |  |  | 5,000,000 ambc_MaximumReimbursementOfOperatingExpenses / dei_LegalEntityAxis = ambc_AmbacAssuranceMember |  |  |
Successor [Member] |  |  |  |  |  |  |
Background And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Proceeds from the sale of Junior Surplus Notes of the Segregated Account |  | 224,262,000 ambc_ProceedsFromTheSaleOfJuniorSurplusNotes / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |  | 0 ambc_ProceedsFromTheSaleOfJuniorSurplusNotes / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |
Common stock, shares issued |  |  |  | 45,000,000 us-gaap_CommonStockSharesIssued / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Warrants Distributed In Bankruptcy |  |  |  | 5,047,138 us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember |  |  |
Two Thousand And Seventeen [Member] | Ambac Assurance [Member] |  |  |  |  |  |  |
Background And Basis Of Presentation [Line Items] |  |  |  |  |  |  |
Maximum Reimbursement Of Operating Expenses after 2017 |  |  |  | $ 4,000,000 ambc_MaximumReimbursementOfOperatingExpensesafter2017 / dei_LegalEntityAxis = ambc_AmbacAssuranceMember / us-gaap_RestructuringCostAndReserveAxis = ambc_TwoThousandAndSeventeenMember |  |  |

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- Definition Junior Surplus Notes issued by the Segregated Account of Ambac Assurance to Ambac upon Ambac's emergence from bankruptcy. These Junior Surplus notes will be includable in surplus for statutory accounting purposes as prescribed or permitted by state laws and regulations. + References No definition available. + Details
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- Definition The maximum number of capital stock permitted to be issued by Ambac's Amended and Restated Certificate of Incorporation. + References No definition available. + Details
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- Definition Transfer restrictions on any person or group of persons already owning this percentage of common stock. + References No definition available. + Details
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- Definition Transfer restrictions on any person or group of persons accumulating this percentage of common stock. + References No definition available. + Details
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- Definition Ability to vote has been restricted for any person owning at least this percentage of common stock to be this percentage minus one vote. + References No definition available. + Details
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- Definition Payment of Deferred Amounts, including accrued interest, that was paid by the Segregated Account in December 2014 as required by the Rehabilitator of the Segregated Account. + References No definition available. + Details
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- Definition Reflects the effective interest rate on Deferred Amounts and Junior Deferred Amounts of the Segregated Account of Ambac as directed by the Rehabilitator of the Segregated Account. + References No definition available. + Details
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- Definition The percentage of unpaid permitted policy claims, together with interest thereon, ("Deferred Amounts") that the Rehabilitator effectuated a payment (as a result of the amended Segregated Account Rehabilitation Plan that was approved in June 2014). This allowed those policyholders that received 25% cash Interim Payments to receive an equalizing payment on their Deferred Amounts. + References No definition available. + Details
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- Definition Reflects the effective annual interest rate on the privately placed Notes issued by the Trust to third party investors. Payments on these Notes will only be made to the extent that the Segregated Account of Ambac Assurance makes payment on the Junior Surplus Notes that serve as collateral for these Notes + References No definition available. + Details
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- Definition In accordance with the provisions of the Cost Allocation Agreement, this element represents allowable reimbursements for reasonable operating expenses through March 2017. + References No definition available. + Details
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- Definition In accordance with the provisions of the Cost Allocation Agreement, this element represents allowable reimbursements for reasonable operating expenses after 2017. + References No definition available. + Details
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- Definition Cash grant released from escrow as part of Mediation Agreement. Balance distributed from Ambac Assurance to Ambac upon emergence from bankruptcy. + References No definition available. + Details
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- Definition Minimum surplus amount that will cap the benefits of the Reinsurance Agreement between Ambac Assurance and the Segregated Account of Ambac Assurance. + References No definition available. + Details
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- Definition Net par outstanding for policies allocated to the Segregated Account of Ambac Assurance. + References No definition available. + Details
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- Definition Payment of Surplus Notes (including accrued interest) that was paid by the Segregated Account and Ambac Assurance in November 2014 after receiving approval of the regulator of both Ambac Assurance and the Segregated Account in October 2014. + References No definition available. + Details
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- Definition Face (par) amount of Owner Trust Certificate at time of issuance. This Owner Trust Certificate was issued by the Trust to Ambac Financial Group, Inc. Trust assets consist of Junior Surplus Notes issued by the Segregated Account of Ambac Assurance. + References No definition available. + Details
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- Definition Face (par) amount of Private Placement instrument at time of issuance. This private placement was issued by the Trust to third party investors. Trust assets consist of Junior Surplus Notes issued by the Segregated Account of Ambac Assurance. + References No definition available. + Details
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- Definition Percentage of the Segregated Account of Ambac Assurance's permitted policy claims that were paid in cash from September 2012 through June 2014. + References No definition available. + Details
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- Definition The stated maturity date of the private placement notes issued by the Trust. + References No definition available. + Details
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- Definition The percentage of the proceeds of the private placement of the par plus accrued and unpaid interest on the junior surplus notes. + References No definition available. + Details
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- Definition Proceeds from the sale of Segregated Account Junior Surplus Notes from Ambac Financial Group to a newly formed Trust + References No definition available. + Details
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- Definition Original issuance amount of the Secured Note issued by Ambac Assurance to the Segregated Account of Ambac Assurance in connection with the establishment of the Ambac Assurance Segregated Account. + References No definition available. + Details
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- Definition Secured note year of maturity. + References No definition available. + Details
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- Definition Current amount outstanding, including capitalized interest, relating to a Secured Note issued by Ambac Assurance to the Segregated Account of Ambac Assurance in connection with the establishment of the Ambac Assurance Segregated Account. + References No definition available. + Details
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- Definition Limit on ability to enter into transactions without the prior consent of the Segregated Account. + References No definition available. + Details
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- Definition Percentage of the Segregated Account of Ambac Assurance's permitted policy claims that are unpaid subsequent to the amendments to the Segregated Account Rehabilitation Plan were confirmed by the Rehabilitation Court in June 2014. + References No definition available. + Details
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- Definition Expiration date of warrants held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column A + Details
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- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(4)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
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- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph i -Subparagraph 2 -Article 4 + Details
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