XML 49 R38.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses) (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Policyholder Benefits And Claims Incurred Net | $ 77 | $ 46 | $ 99 | $ 40
U S Public Finance Insurance [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Policyholder Benefits And Claims Incurred Net | 9 | 8 | 18 | 2
Second-Lien RMBS [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Policyholder Benefits And Claims Incurred Net | 21 | 36 | 34 | 29
First-Lien RMBS [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Policyholder Benefits And Claims Incurred Net | 35 | (26) | 61 | (16)
Other [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Policyholder Benefits And Claims Incurred Net | $ 12 | $ 28 | $ (14) | $ 25

X
- Definition Loss And Loss Adjustment Expense Reserves [Line Items] + References No definition available. + Details
Name: | mbi_LossAndLossAdjustmentExpenseLineItems
Namespace Prefix: | mbi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6811-158387 + Details
Name: | us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mbi_USPublicFinanceInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mbi_SecondLienResidentialMortgageBackedSecuritiesAndReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mbi_FirstLienResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mbi_OtherLossesAndLossAndLossAdjustmentExpenseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |