XML 67 R79.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Business Segments (Summary Of Premiums Earned On Financial Guarantees And Insured Derivatives By Geographic Location Of Risk) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2013 | Sep. 30, 2012 | Sep. 30, 2013 | Sep. 30, 2012
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | $ 112 | $ 168 | $ 377 | $ 506
United States [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 82 | 141 | 297 | 402
United Kingdom [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 9 | 9 | 26 | 27
Europe Excluding United Kingdom [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 3 | 3 | 9 | 12
Internationally Diversified [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 2 | 3 | 8 | 13
Central And South America [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 13 | 8 | 28 | 40
Asia [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | 1 | 2 | 3 | 4
Other [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Total premiums earned | $ 2 | $ 2 | $ 6 | $ 8

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