XML 59 R43.htm IDEA: XBRL DOCUMENT
v3.24.2.u1

Investments - Summary of Gross Unrealized Losses and Fair Values of Ambac's Available-for-Sale Investments (Details) $ in Millions | Jun. 30, 2024 USD ($) | Dec. 31, 2023 USD ($)
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 372 | $ 187
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 5 | 4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 787 | 844
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 71 | 68
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,159 | 1,032
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 78 | 71
DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss, including pledged securities | 7 |
Debt Securities , Available for sale, Continuous Unrealized Loss Position, | 398 | 187
Debt Securities, Available for sale, Unrealized Loss Position, Including Pledged Securities |  | 1,032
Short-term Investments [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 46 | 4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 46 | 4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 0 | 0
Ambac Insured Securities | Parsed Fixed Income Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | 5,000 |
Fixed Income Investments And Other Investments [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 77 | 71
Fixed Income Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 326 | 184
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 5 | 4
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 787 | 844
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 71 | 68
Debt Securities, Available-for-sale, Unrealized Loss Position | 1,113 | 1,028
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 77 | 71
Fixed Income Securities [Member] | Municipal Bonds [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 21 | 7
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 15 | 16
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 1 | 1
Debt Securities, Available-for-sale, Unrealized Loss Position | 35 | 23
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 2 | 1
Fixed Income Securities [Member] | Corporate Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 125 | 75
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 3 | 2
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 493 | 509
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 43 | 43
Debt Securities, Available-for-sale, Unrealized Loss Position | 618 | 584
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 46 | 44
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | 733,000 |
Fixed Income Securities [Member] | Debt Security, Government, Non-US [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | $ 25 | 8
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 55 | 56
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 7 | 6
Debt Securities, Available-for-sale, Unrealized Loss Position | 80 | 64
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 7 | 6
Fixed Income Securities [Member] | US Government Debt Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 58 | 27
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1 | 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 37 | 37
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 3 | 2
Debt Securities, Available-for-sale, Unrealized Loss Position | 95 | 63
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 4 | 4
Fixed Income Securities [Member] | US Government Debt Securities [Member] | Asset Pledged as Collateral [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 25 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 25 | 0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 1 | 0
Fixed Income Securities [Member] | Residential Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 16 | 6
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 113 | 98
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 13 | 14
Debt Securities, Available-for-sale, Unrealized Loss Position | 129 | 104
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 13 | 14
Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 17 | 3
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Unrealized Loss Position | 17 | 3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 0 | 0
Fixed Income Securities [Member] | Collateralized Debt Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 18 | 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 0 | 0
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 3 | 93
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 1
Debt Securities, Available-for-sale, Unrealized Loss Position | 22 | 95
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | 0 | 1
Fixed Income Securities [Member] | Asset-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months | 45 | 57
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | 1 | 1
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer | 72 | 35
Debt Securities, Available-for-sale, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 4 | 1
Debt Securities, Available-for-sale, Unrealized Loss Position | 117 | 92
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 5 | 1
Debt Securities Available for Sale Unrealized Loss Measured as a Percent of Amortized Cost | 5.00% |
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | 13,000 |
Fixed Income Securities [Member] | Ambac Insured Securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 13 |
Debt Securities Available for Sale Unrealized Loss Measured as a Percent of Amortized Cost | 12.00% |
Debt Securities, Available-for-Sale, Unrealized Loss Position, Number of Positions | 15,000 |
Collateral Pledged [Member] | Fixed Income Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 1 | 0
Collateral Pledged [Member] | Fixed Income Securities [Member] | Short-term Investments [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax | $ 0 | $ 0

X
- Definition Debt Securities , Available for sale, Continuous Unrealized Loss Position, Less than 12 Months, Including Pledged Securities + References No definition available. + Details
Name: | ambc_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss, including pledged securities + References No definition available. + Details
Name: | ambc_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLossIncludingPledgedSecurities
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Securities Available for Sale Unrealized Loss Measured as a Percent of Amortized Cost + References No definition available. + Details
Name: | ambc_DebtSecuritiesAvailableForSaleUnrealizedLossMeasuredAsAPercentOfAmortizedCost
Namespace Prefix: | ambc_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Securities, Available for sale, Unrealized Loss Position, Accumulated Loss, Less than 12 Months, Including Pledged Securities + References No definition available. + Details
Name: | ambc_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLossLessThan12MonthsIncludingPledgedSecurities
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-5 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-6 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479106/326-30-50-4 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-3 + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ShortTermInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=ambc_AmbacInsuredSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ambc_ParsedInvestmentTypeAxis=ambc_ParsedFixedIncomeSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ambc_FixedIncomeInvestmentsAndOtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MunicipalBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PledgedStatusAxis=us-gaap_AssetPledgedAsCollateralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CollateralizedDebtObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |