XML 62 R36.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Background and Basis of Presentation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2012 | Dec. 31, 2010 | Dec. 31, 2011
Background And Basis Of Presentation [Line Items] |  |  |
Net par exposure for policies allocated to the segregated account | $ 30,450,626 |  |
Issuance of secured note to segregated account |  | 2,000,000 |
Secured note maturity year |  | 2050 |
Interest on the secured note accrues |  | 4.50% |
Available secured notes including capitalized interest | 897,248 |  |
Minimum surplus amount | 100,000 |  |
Percentage of permitted policy claim | 25.00% |  |
Insurance liabilities allocated to segregated account | 6,596,843 |  |
Insurance liabilities not assumed under Reinsurance Agreement | 296,018 |  |
Maximum limit for aggregate face amount of allowed and disputed general unsecured claims | 50,000 |  |
Amount shall have been paid or paid into escrow by the company | 30,000 |  |
Current cash and investments | 31,459 |  |
Restricted cash | $ 2,500 |  | $ 2,500
Ambac [Member] |  |  |
Background And Basis Of Presentation [Line Items] |  |  |
Shareholders ownership interest | 5.00% |  |
Increase in ownership percentage, by value | 50.00% |  |
Increase in ownership percentage, rolling period beginning with the last Ownership Change | Three-year |  |
Beneficially owned shares by the holders | 13,500,000 |  |
Percentage of stock value of reorganized company | 4.50% |  |

X
- Definition Accrued Interest Rate, Percentage + References No definition available. + Details
Name: | abk_AccruedInterestRatePercentage
Namespace Prefix: | abk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | abk_BackgroundAndBasisOfPresentationLineItems
Namespace Prefix: | abk_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Beneficial Ownership Of Company Common Stock Held By External Investor Shares + References No definition available. + Details
Name: | abk_BeneficialOwnershipOfCompanyCommonStockHeldByExternalInvestorShares
Namespace Prefix: | abk_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Change In Beneficial Ownership Percentage + References No definition available. + Details
Name: | abk_ChangeInBeneficialOwnershipPercentage
Namespace Prefix: | abk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Debt Instrument Maturity Year + References No definition available. + Details
Name: | abk_DebtInstrumentMaturityYear
Namespace Prefix: | abk_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Increase In Percentage Of Stock Ownership By Value + References No definition available. + Details
Name: | abk_IncreaseInPercentageOfStockOwnershipByValue
Namespace Prefix: | abk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Insurance Liabilities + References No definition available. + Details
Name: | abk_InsuranceLiabilities
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of the Segregated Account's insurance liabilities not assumed under the Reinsurance Agreement. + References No definition available. + Details
Name: | abk_InsuranceLiabilitiesNotAssumedByEntityAssurance
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount placed in escrow under the mediation agreement between subsidiary and parent company. + References No definition available. + Details
Name: | abk_IntercompanyEscrow
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The maximum unsecured face amount of allowed and unsecured general unsecured claims under the Reorganization Plan. + References No definition available. + Details
Name: | abk_MaximumUnsecuredClaims
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Net par exposure for policies allocated to the Segregated Account of Ambac Assurance. + References No definition available. + Details
Name: | abk_NetParExposureForPoliciesAllocatedToSegregatedAccount
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Shareholders ownership interest of 5% or more. + References No definition available. + Details
Name: | abk_OwnershipInterest
Namespace Prefix: | abk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the customer may deposit additional funds at any time and effectively may withdraw funds at any time without prior notice or penalty. Short-term investments, exclusive of cash equivalents, generally consist of marketable securities intended to be sold within one year (or the normal operating cycle if longer) and may include trading securities, available-for-sale securities, or held-to-maturity securities (if maturing within one year), as applicable. + References No definition available. + Details
Name: | abk_ParentCompanyCashAndShortTermInvestments
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of claim permitted to be paid. + References No definition available. + Details
Name: | abk_PaymentAsPercentageOfPermittedPolicyClaim
Namespace Prefix: | abk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Payment of consideration under settlement agreement principal amount. + References No definition available. + Details
Name: | abk_PaymentOfConsiderationUnderSettlementAgreementPrincipalAmount
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Settlement agreement surplus notes principal amount outstanding. + References No definition available. + Details
Name: | abk_SettlementAgreementSurplusNotesPrincipalAmountOutstanding
Namespace Prefix: | abk_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Vesting Period + References No definition available. + Details
Name: | abk_VestingPeriod
Namespace Prefix: | abk_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Audit and Accounting Guide (AAG) -Number AAG-BRD -Paragraph 80 -Subparagraph Exhibit 4-8, 3 -IssueDate 2006-05-01 -Chapter 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of statutory capital required to be maintained as of the balance sheet date under prescribed or permitted statutory accounting practices. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 60 -Paragraph 60 -Subparagraph h(2) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_StatutoryAccountingPracticesStatutoryCapitalAndSurplusRequired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant