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Commitments and Contingencies (Narrative) (Detail) | 12 Months Ended
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Dec. 31, 2013 numberoflawsuits
Commitments and Contingencies [Abstract] |
Other material lawsuits pending | 0

X
- Definition Other material lawsuits pending + References No definition available. + Details
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Namespace Prefix: | mbi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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