XML 147 R58.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Loss And Loss Adjustment Expense Reserves (Summary Of Credit Impairments Related To Derivatives) (Narrative) (Detail) (USD $) | 12 Months Ended | 36 Months Ended
--- | --- | ---
Dec. 31, 2012 SecurityLoan | Dec. 31, 2012 SecurityLoan
Loss And Loss Adjustment Expense Reserves [Line Items] |  |
Discount rate of credit impairments | 5.72% |
Number of structured CMBS commutations |  | 66
Gross exposure commuted on CMBS insured derivatives |  | $ 33,100,000,000
Loan balance greater than with debt service coverage ratio | 75,000,000 |
Debt service coverage ratio | 1.0 |
Proprietary performance data on CRE loans, amount | 80,000 | 80,000
Representative Cohorts based on DSCR and property type | 168 |
Losses and LAE | 50,000,000 |
Additional estimated credit impairments on CMBS derivatives | 852,000,000 |
Aggregate ITD credit impairment on CMBS derivatives |  | 3,600,000,000
CMBS severities exceeded complete loss in certain instances | 100.00% |
Maximum [Member] |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |
Percentage of loss on liquidation | 2.00% |
Minimum [Member] |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |
Percentage of loss on liquidation | 1.00% |
CRE CDO [Member] |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |
Losses and LAE | $ 46,000,000 |

X
- Definition Additional Estimated Credit Impairment On Commercial Mortgage Backed Securities Derivatives + References No definition available. + Details
Name: | mbi_AdditionalEstimatedCreditImpairmentOnCommercialMortgageBackedSecuritiesDerivatives
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Aggregate Itd Credit Impairment On Commercial Mortgage Backed Securities Derivatives + References No definition available. + Details
Name: | mbi_AggregateItdCreditImpairmentOnCommercialMortgageBackedSecuritiesDerivatives
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Commercial Mortgage Backed Securities Severities Exceeded Complete Loss In Certain Instances + References No definition available. + Details
Name: | mbi_CommercialMortgageBackedSecuritiesSeveritiesExceededCompleteLossInCertainInstances
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Discount Rate Of Credit Impairments + References No definition available. + Details
Name: | mbi_DiscountRateOfCreditImpairments
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gross Exposure Commuted On Commercial Mortgage Backed Securities Insured Derivatives + References No definition available. + Details
Name: | mbi_GrossExposureCommutedOnCommercialMortgageBackedSecuritiesInsuredDerivatives
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Loan Balance Greater Than With Debt Service Coverage Ratio + References No definition available. + Details
Name: | mbi_LoanBalanceGreaterThanWithDebtServiceCoverageRatio
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Number of representative cohorts in commercial real estate proprietary model based on debt service coverage ratio ("DSCR") and property type. + References No definition available. + Details
Name: | mbi_NumberOfRepresentativeCohortsInCommercialRealEstateProprietaryModelBasedOnDebtServiceCoverageRatioAndPropertyType
Namespace Prefix: | mbi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Structured CMBS Commutations + References No definition available. + Details
Name: | mbi_NumberOfStructuredCommercialMortgageBackedSecuritiesCommutations
Namespace Prefix: | mbi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage Of Loss On Liquidation + References No definition available. + Details
Name: | mbi_PercentageOfLossOnLiquidation
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Proprietary Performance Data On CRE Loans Amount + References No definition available. + Details
Name: | mbi_ProprietaryPerformanceDataOnCreLoansAmount
Namespace Prefix: | mbi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The ratio applied to the debt for purposes of determining the number of shares of the equity security into which the debt will be converted. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Conversion Rate -URI http://asc.fasb.org/extlink&oid=6509012 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(5)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionRatio
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

X
- Definition Provision for benefits, claims and claims settlement expenses incurred during the period net of the effects of contracts assumed and ceded. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 5 -Article 7 + Details
Name: | us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration