XML 64 R60.htm IDEA: XBRL DOCUMENT
v3.20.1

Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2020 | Mar. 31, 2019 | Dec. 31, 2019 | Dec. 31, 2018
Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | $ 5,884 | $ 7,139 | $ 6,207 | $ 6,930
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 130 | 160 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (377) | 135 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (76) | (87) |  |
Fair Value, Inputs, Level 3 [Member] | Investments [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 66 | 72 | 72 | 72
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | 0 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (6) | 0 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 | 0 |  |
Fair Value, Inputs, Level 3 [Member] | Other Assets [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 3 | 4 | 3 | 5
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | 0 |  |
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 77 | 53 | 66 | 46
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 12 | 8 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (1) | (1) |  |
Variable Interest Entity, Primary Beneficiary [Member] | Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 2,932 | 4,376 | 3,108 | 4,288
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 88 | 88 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | (190) | 85 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | (74) | (85) |  |
Variable Interest Entity, Primary Beneficiary [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 0 | (224) | 0 | (217)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 0 | (3) |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | 0 | (4) |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements | 0 | 0 |  |
Variable Interest Entity, Primary Beneficiary [Member] | Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability | 2,806 | 2,858 | $ 2,957 | $ 2,737
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings | 30 | 67 |  |
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss | $ (181) | $ 54 |  |
Variable Interest Entity [Member] |  |  |  |
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31) |  |  |  |
Estimated Future Premium Payments Minimum Discounted Rate | 2.30% |  |  |
Estimated Future Premium Payments Maximum Discounted Rate | 11.00% |  |  |

X
- Definition Estimated Future Premium Payments Maximum Discounted Rate + References No definition available. + Details
Name: | ambc_EstimatedFuturePremiumPaymentsMaximumDiscountedRate
Namespace Prefix: | ambc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Estimated Future Premium Payments Minimum Discounted Rate + References No definition available. + Details
Name: | ambc_EstimatedFuturePremiumPaymentsMinimumDiscountedRate
Namespace Prefix: | ambc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset or liability. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiability
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of gain or loss included in earnings arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInEarnings
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain or loss included in other comprehensive income arising from financial instruments measured on a recurring basis using unobservable inputs. + References No definition available. + Details
Name: | ambc_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetOrLiabilityGainLossIncludedInOtherComprehensiveIncomeLoss
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_InvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_OtherAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=us-gaap_LoanOriginationCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_LoansReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=us-gaap_LongTermDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByLiabilityClassAxis=us-gaap_InvestmentContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=ambc_VariableInterestEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |