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

Insurance [Line Items]

No definition available.

Name:	ambc_InsuranceLineItems
Namespace Prefix:	ambc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Number of Reinsurers Covering Majority

No definition available.

Name:	ambc_NumberOfReinsurersCoveringMajority
Namespace Prefix:	ambc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Percentage of Ceded Reinsurance Recoverable Represented by Top Three

No definition available.

Name:	ambc_PercentageOfCededReinsuranceRecoverableRepresentedByTopThree
Namespace Prefix:	ambc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Reinsurance Recoverable Credit Exposure

No definition available.

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

Reinsurance Recoverable, Gross, All Other

No definition available.

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

Uncollateralized Credit Exposure Supoorted by Unlimited Uncapped Indemnity

No definition available.

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

Unsecured Reinsurance Recoverable, All Other

No definition available.

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

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.

No definition available.

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

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

No definition available.

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

The carrying amount as of the balance sheet date of the known and estimated amounts owed to insurers under reinsurance treaties or other arrangements.

No definition available.

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

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=124255953&loc=SL82919253-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7A
-URI https://asc.fasb.org/extlink&oid=123577603&loc=SL6953401-111524

Name:	us-gaap_ReinsuranceRecoverablesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	us-gaap_CededCreditRiskAxis=ambc_QBEInsuranceCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ScheduleOfMalpracticeInsuranceTypeAndTierIdentifierAxis=us-gaap_PropertyAndCasualtyCommercialInsuranceProductLineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=ambc_AssuredGuarantyReLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ScheduleOfMalpracticeInsuranceTypeAndTierIdentifierAxis=us-gaap_FinancialGuaranteeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: