XML 118 R103.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Business Segments (Summary Of Premiums Earned On Financial Guarantees And Insured Derivatives By Geographic Location Of Risk) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | $ 385 | $ 416 | $ 494
United States [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 310 | 299 | 391
United Kingdom [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 30 | 36 | 34
Europe Excluding United Kingdom [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 4 | 7 | 11
Internationally Diversified [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 3 | 9 | 9
Central And South America [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 29 | 49 | 36
Asia [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | 3 | 4 | 4
Other [Member] |  |  |
Segment Reporting Information [Line Items] |  |  |
Total premiums earned | $ 6 | $ 12 | $ 9

X
- Definition Premiums Earned Net Financial Guarantee Insurance Contracts And Insured Derivatives + References No definition available. + Details
Name: | mbi_PremiumsEarnedNetFinancialGuaranteeInsuranceContractsAndInsuredDerivatives
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=mbi_EuropeExcludingUnitedKingdomMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=mbi_InternationallyDiversifiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=mbi_CentralAndSouthAmericaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=us-gaap_AsiaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=mbi_OtherLocationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |