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Commitments and Contingencies (Narrative) (Detail) | 3 Months Ended
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Mar. 31, 2015 Lawsuits
Commitments and Contingencies [Abstract] |
Other material lawsuits pending | 0 mbi_NumberOfOtherLawsuits

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- Definition Other material lawsuits pending + References No definition available. + Details
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Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: | us-gaap_
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