XML 13 R54.htm IDEA: XBRL DOCUMENT v2.4.0.6

Financial Guarantee Insurance Contracts - Summary of Rollforward of RMBS Subrogation, by Estimation Approach (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 Transactions
Rollforward:
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	$ 2,523,225
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	49
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	49
Changes recognized in 2012:
Additional transactions reviewed
Additional adverse sample loans reviewed
Impact of sponsor actions	(54,195)
All other changes	18,339
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	2,487,369
Random samples [Member]
Rollforward:
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	1,080,408
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	22
Changes recognized in 2013: Additional transactions reviewed	0
Additional adverse sample loans reviewed	0
Impact of sponsor actions	(2)
All other changes	0
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	20
Changes recognized in 2012:
Additional transactions reviewed
Additional adverse sample loans reviewed
Impact of sponsor actions	(54,195)
All other changes	(22,570)
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	1,003,643
Adverse samples [Member]
Rollforward:
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	1,442,817
Discounted RMBS subrogation (gross of reinsurance) at December 31, 2012	27
Changes recognized in 2013: Additional transactions reviewed	0
Additional adverse sample loans reviewed	0
Impact of sponsor actions	0
All other changes	2
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	29
Changes recognized in 2012:
Additional transactions reviewed
Additional adverse sample loans reviewed
All other changes	40,909
Discounted RMBS subrogation (gross of reinsurance) at March 31, 2013	$ 1,483,726

X

- Definition

This element represents the change in RMBS subrogation due to additional adverse sample loans reviewed.

+ References

No definition available.

+ Details

Name:	ambc_AdditionalAdverseSampleLoansReviewedChangeInRmbsSubrogation
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Additional Adverse Sample Loans Reviewed Number Of Transactions

+ References

No definition available.

+ Details

Name:	ambc_AdditionalAdverseSampleLoansReviewedNumberOfTransactions
Namespace Prefix:	ambc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

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

- Details

Name:	ambc_ChangesRecognizedInResidentialMortgageBackedSecurityAbstract
Namespace Prefix:	ambc_
Data Type:	xbrli:stringItemType
Balance Type:	na
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_ImpactOfSponsorActions
Namespace Prefix:	ambc_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

Number Of Additional Rmbs Transactions Reviewed With Potential Recoveries

+ References

No definition available.

+ Details

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

X

- Definition

Number of total remediation transactions.

+ References

No definition available.

+ Details

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

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

Other Changes Rmbs Subrogation Number Of Transactions

+ References

No definition available.

+ Details

Name:	ambc_OtherChangesRmbsSubrogationNumberOfTransactions
Namespace Prefix:	ambc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Definition

Schedule Of Insured Financial Obligations With Credit Deterioration Reductions Of Gross Claim Liability Subrogation Rmbs

+ References

No definition available.

+ Details

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