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Financial Guarantee Insurance Contracts - Summary of Balance of RMBS Subrogation Recoveries and Related Claim Liabilities, by Estimation Approach (Detail) - USD ($) $ in Thousands | 4 Months Ended | 8 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Apr. 30, 2013 | Dec. 31, 2013 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2012
Successor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | $ 2,482,918 | $ 2,206,598 | $ 2,829,575 | $ 2,523,540 |
Additional Transactions Reviewed Changes in RMBS Subrogation |  | 2,451 | 0 | 24,565 |
Changes in Estimation Approach In Rmbs Subrogation |  | 0 | 0 | 198,875 |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation |  | 98 | 0 | (146,270) |
Other Changes Rmbs Subrogation |  | (278,869) | 306,035 | 239,772 |
Successor [Member] | Random Samples [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Gross loss reserve before subrogation recoveries |  |  | 1,850,804 | 1,897,426 |
Subrogation recoveries |  |  | 2,829,575 | 2,523,540 |
Gross loss reserve after subrogation recoveries |  |  | (978,771) | (626,114) |
Predecessor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | 2,482,918 |  |  |  | $ 2,523,225
Additional Transactions Reviewed Changes in RMBS Subrogation | 0 |  |  |  |
Changes in Estimation Approach In Rmbs Subrogation | 0 |  |  |  |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation | (54,195) |  |  |  |
Other Changes Rmbs Subrogation | 13,888 |  |  |  |
Adverse Samples [Member] | Successor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | 1,478,666 | 1,252,773 | 0 | 0 |
Additional Transactions Reviewed Changes in RMBS Subrogation |  | 0 | 0 | 0 |
Changes in Estimation Approach In Rmbs Subrogation |  | 0 | 0 | (1,218,681) |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation |  | 98 | 0 | 0 |
Other Changes Rmbs Subrogation |  | (225,991) | 0 | (34,092) |
Adverse Samples [Member] | Predecessor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | 1,478,666 |  |  |  | 1,442,817
Additional Transactions Reviewed Changes in RMBS Subrogation | 0 |  |  |  |
Changes in Estimation Approach In Rmbs Subrogation | 0 |  |  |  |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation | 0 |  |  |  |
Other Changes Rmbs Subrogation | 35,849 |  |  |  |
Random Samples [Member] | Successor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | 1,004,252 | 953,825 | 2,829,575 | 2,523,540 |
Additional Transactions Reviewed Changes in RMBS Subrogation |  | 2,451 | 0 | 24,565 |
Changes in Estimation Approach In Rmbs Subrogation |  | 0 | 0 | 1,417,556 |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation |  | 0 | 0 | (146,270) |
Other Changes Rmbs Subrogation |  | $ (52,878) | $ 306,035 | $ 273,864 |
Random Samples [Member] | Predecessor [Member] |  |  |  |  |
Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] |  |  |  |  |
Subrogation recoveries | 1,004,252 |  |  |  | $ 1,080,408
Additional Transactions Reviewed Changes in RMBS Subrogation | 0 |  |  |  |
Changes in Estimation Approach In Rmbs Subrogation | 0 |  |  |  |
Impact Of Sponsor Actions In Residential Mortgage Backed Securities Subrogation | (54,195) |  |  |  |
Other Changes Rmbs Subrogation | $ (21,961) |  |  |  |

X
- Definition This element represents the change in subrogation due to additional transactions reviewed. + References No definition available. + Details
Name: | ambc_AdditionalTransactionsReviewedChangesinRMBSSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents the change in subrogation due to changes in estimation approach. + References No definition available. + Details
Name: | ambc_ChangesinEstimationApproachInRmbsSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The change in RMBS subrogation due to the impact of sponsor actions which includes loan repurchases, direct payments, and other contributions from sponsors. + References No definition available. + Details
Name: | ambc_ImpactOfSponsorActionsInResidentialMortgageBackedSecuritiesSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents the changes in RMBS subrogation for reasons other than additional transactions being reviewed, adverse loans being reviewed or due to adverse loans being repurchased by the sponsor. + References No definition available. + Details
Name: | ambc_OtherChangesRmbsSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Schedule Of Balance Of Rmbs Subrogation Recoveries And Related Claim Liabilities By Estimation Approach [Line Items] + References No definition available. + Details
Name: | ambc_ScheduleOfBalanceOfRmbsSubrogationRecoveriesAndRelatedClaimLiabilitiesByEstimationApproachLineItems
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This element represents the related gross claim liability net of subrogation recoveries for RMBS financial guarantee insurance contracts with credit deterioration that have estimated subrogation recoveries. + References No definition available. + Details
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationRmbsGrossClaimLiabilitiesAfterSubrogationRecoveries
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This element represents the related gross claim liability for RMBS financial guarantee insurance contracts with credit deterioration that have estimated subrogation recoveries. + References No definition available. + Details
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationRmbsGrossClaimLiabilitiesBeforeSubrogationRecoveries
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
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- Details
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- Details
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- Details
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- Details
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