Ceded Loss And Loss Expenses Paid Not Yet Recovered

No definition available.

Name:	ambc_CededLossAndLossExpensesPaidNotYetRecovered
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Includes the unexpired portion of financial guarantee premiums ceded on policies as of the balance sheet date and reinsurance recoverables on claims or claim adjustment expense paid by the ceding insurer.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Number of Reinsurers Covering Majority

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Ceded Reinsurance Recoverable Represented by Top Three

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Reinsurance Recoverable Credit Exposure

+ References

No definition available.

+ Details

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

- Definition

Reinsurance Recoverable, Gross, All Other

+ References

No definition available.

+ Details

Name:	ambc_ReinsuranceRecoverableGrossAllOther
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]

+ References

No definition available.

+ Details

Name:	ambc_SummaryOfCededParAndNetUnsecuredReinsuranceRecoverableLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Uncollateralized Credit Exposure Supoorted by Unlimited Uncapped Indemnity

+ References

No definition available.

+ Details

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

- Definition

Unsecured Reinsurance Recoverable, All Other

+ References

No definition available.

+ Details

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

- Definition

Represents reinsurance recoverables on paid and unpaid losses and deferred ceded premiums, net of ceded premiums payables due to reinsurers, letters of credit, and collateral posted for the benefit of the cedant.

+ References

No definition available.

+ Details

Name:	ambc_UnsecuredReinsuranceRecoverables
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

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-SubTopic 605
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of allowance for credit loss on reinsurance recoverable.

+ References

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

- Definition

Amount before valuation allowance recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

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+ Details

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- Details

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Insurance - Summary of Percentage Ceded to Reinsurers and Reinsurance Recoverable and Rating Levels (Details) $ in Thousands	Mar. 31, 2026 USD ($)	Dec. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Ceded Loss And Loss Expenses Paid Not Yet Recovered			$ 56,190
Reinsurance Recoverable, Allowance for Credit Loss	$ 100	$ 100
Reinsurance Recoverables, Gross	469,859
Unsecured Reinsurance Recoverables	327,935
Reinsurance Recoverable, Gross, All Other	225,084
Unsecured Reinsurance Recoverable, All Other	112,773
Letters of Credit Outstanding, Amount	$ 80,351
Number of Reinsurers Covering Majority	5
Percentage of Ceded Reinsurance Recoverable Represented by Top Three	52.10%
Uncollateralized Credit Exposure Supoorted by Unlimited Uncapped Indemnity	$ 21,273	23,530
Deferred Ceded Premiums And Reinsurance Recoverables	615,279
Reinsurance Recoverable Credit Exposure	327,935	$ 311,795
QBE Insurance Corporation \| Property and Casualty, Commercial Insurance \| Standard & Poor's, A Rating
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	17,989
Unsecured Reinsurance Recoverables	17,989
Assured Guaranty Re Ltd \| Financial Guarantee \| Standard & Poor's, A+ Rating
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	65,092
Unsecured Reinsurance Recoverables	63,828
General Reinsurance Company \| Property and Casualty, Commercial Insurance \| Standard Poors A Plus Plus Rating
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	128,406
Unsecured Reinsurance Recoverables	100,301
Swiss Reinsurance America Corporation \| Financial Guarantee \| Standard & Poor's, A+ Rating
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	15,512
Unsecured Reinsurance Recoverables	14,788
Swiss Reinsurance America Corporation \| Financial Guarantee \| Standard & Poors, No Rating
Summary of Ceded Par and Net Unsecured Reinsurance Recoverable [Line Items]
Reinsurance Recoverables, Gross	17,776
Unsecured Reinsurance Recoverables	$ 18,256