XML 17 R48.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Fair Value Of Financial Instruments (Narrative) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended |
--- | --- | ---
Mar. 31, 2014 | Mar. 31, 2013 | Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Percentage of insured credit derivatives, value under Direct Price Model and Dual-Default Model | 8.00% |  |
Percentage of sector-specific transactions valued using BET model | 5.00% |  |
Percentage of transactions valued using corporate spreads used | 53.00% |  |
Percentage of transactions valued using spread benchmarked from most relevant spread source | 42.00% |  |
Percentage of transactions valued using WARF-sourced and/or ratings sourced credit spreads | 73.00% |  |
Net insured derivative liability | $ 309 |  | $ 1,200
Impact of including the nonperformance risk in valuation of pre-tax net insured derivative liability | 94 |  | 394
Percentage of level 3 assets at fair value in total assets measured at fair value value | 24.00% |  | 22.00%
Percentage of level 3 liabilities at fair value in total liabilities measured at fair value | 48.00% |  | 61.00%
Transfers into Level 3 | 160 | 85 |
Transfers out of Level 3 | 14 | 78 |
Transfers into Level 2 | 14 | 78 |
Transfers out of Level 2 | 160 | 85 |
Transfers into or out of Level 1 | $ 0 | $ 0 |
B E T Valuation Model [Member] |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |
Percentage of insured credit derivatives, fair value using the BET model | 92.00% |  |

X
- Definition Approximate percentage of level 3 assets at fair value in total assets measured at fair value. + References No definition available. + Details
Name: | mbi_ApproximatePercentageOfLevel3AssetsAtFairValueInTotalAssetsMeasuredAtFairValue
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Approximate percentage of level 3 liabilities at fair value in total liabilities measured at fair value. + References No definition available. + Details
Name: | mbi_ApproximatePercentageOfLevel3LiabilitiesAtFairValueInTotalLiabilitiesMeasuredAtFairValue
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Impact Of Non Performance Risk On Insured Derivative Liability + References No definition available. + Details
Name: | mbi_ImpactOfNonPerformanceRiskOnInsuredDerivativeLiability
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage Of Insured Credit Derivatives Value Under Bet Model + References No definition available. + Details
Name: | mbi_PercentageOfInsuredCreditDerivativesValueUnderBetModel
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of insured credit derivatives value under direct price model and dual default model + References No definition available. + Details
Name: | mbi_PercentageOfInsuredCreditDerivativesValueUnderDirectPriceModelAndDualDefaultModel
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage Of Sector Specific Transactions Valued Using BET Model + References No definition available. + Details
Name: | mbi_PercentageOfSectorSpecificTransactionsValuedUsingBetModel
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage Of Transactions Valued Using Corporate Spread + References No definition available. + Details
Name: | mbi_PercentageOfTransactionsValuedUsingCorporateSpread
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of Transactions Valued Using Spread Benchmark From Most Relevant Spread Source + References No definition available. + Details
Name: | mbi_PercentageOfTransactionsValuedUsingSpreadBenchmarkFromMostRelevantSpreadSource
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of Transactions Valued Using Warf Sourced And Or Ratings Source Credit Spread + References No definition available. + Details
Name: | mbi_PercentageOfTransactionsValuedUsingWarfSourcedAndOrRatingsSourceCreditSpread
Namespace Prefix: | mbi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Transfers of assets measured at fair value on a recurring basis into and out of level one during the period. + References No definition available. + Details
Name: | mbi_TransfersIntoAndOutOfLevelOne
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Transfers of assets measured at fair value on a recurring basis into level three during the period. + References No definition available. + Details
Name: | mbi_TransfersIntoLevelThree
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Transfers of assets measured at fair value on a recurring basis into level two during the period. + References No definition available. + Details
Name: | mbi_TransfersIntoLevelTwo
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Transfers of assets measured at fair value on a recurring basis out of level three during the period. + References No definition available. + Details
Name: | mbi_TransfersOutOfLevelThree
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Transfers of assets measured at fair value on a recurring basis out of level two during the period. + References No definition available. + Details
Name: | mbi_TransfersOutOfLevelTwo
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. + References Reference 1: 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 + Details
Name: | us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration