XML 36 R87.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Derivative Instruments - Summarize Information by Major Category of CDS Contracts (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2012 Transactions | Dec. 31, 2011 Transactions
Summary of information by major category of CDS contracts |  |
Number of CDS transactions | 51 | 68
Remaining expected weighted-average life of obligations (in years) | 3 years 7 months 6 days | 4 years 1 month 6 days
Gross principal notional outstanding | $ 11,281,777 | $ 14,166,612
Net derivative liabilities at fair value | (62,854) |
Credit derivatives [Member] |  |
Summary of information by major category of CDS contracts |  |
Net derivative liabilities at fair value | (213,585) | (190,653)
CLO [Member] |  |
Summary of information by major category of CDS contracts |  |
Number of CDS transactions | 30 | 44
Remaining expected weighted-average life of obligations (in years) | 2 years 2 months 12 days | 2 years 8 months 12 days
Gross principal notional outstanding | 6,155,767 | 8,228,577
CLO [Member] | Credit derivatives [Member] |  |
Summary of information by major category of CDS contracts |  |
Net derivative liabilities at fair value | (34,645) | (54,320)
Other [Member] |  |
Summary of information by major category of CDS contracts |  |
Number of CDS transactions | 21 | 24
Remaining expected weighted-average life of obligations (in years) | 5 years 2 months 12 days | 6 years
Gross principal notional outstanding | 5,126,010 | 5,938,035
Other [Member] | Credit derivatives [Member] |  |
Summary of information by major category of CDS contracts |  |
Net derivative liabilities at fair value | $ (178,940) | $ (136,333)

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

X
- Definition Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_DerivativeAverageRemainingMaturity1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of the gross liabilities less the gross assets of a derivative liability or group of derivative liabilities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611 + Details
Name: | us-gaap_DerivativeLiabilityFairValueNet1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of derivative instruments of a particular group held by the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 + Details
Name: | us-gaap_DerivativeNumberOfInstrumentsHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate notional amount of credit risk derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 + Details
Name: | us-gaap_NotionalAmountOfCreditRiskDerivatives
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant