XML 78 R57.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Loss And Loss Adjustment Expense Reserves (Schedule Of Losses And Loss Adjustment Expenses Reserves and Recoveries) (Detail) - USD ($) $ in Millions | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | --- | ---
Loss And Lae Reserves [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Loss and loss adjustment expense reserves |  | $ 934 | $ 979 | $ 541
Insurance Loss Recoverable [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Insurance Loss Recoverable |  | 1,564 | 511 | $ 504
U S Public Finance Insurance [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Insurance Loss Recoverable |  | 571 | 333 |
Loss and loss adjustment expense reserves |  | 551 | 512 |
International And Structured Finance Insurance [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Insurance Loss Recoverable | [1] | 1,430 | 1,478 |
Loss and loss adjustment expense reserves | [1] | 637 | 710 |
International And Structured Finance Insurance [Member] | Variable Interest Entity Primary Beneficiary [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Insurance Loss Recoverable | [1] | (437) | (1,300) |
Loss and loss adjustment expense reserves | [1] | (254) | (243) |
International And Structured Finance Insurance [Member] | Variable Interest Entity Primary Beneficiary [Member] | Loan Repurchase Commitments [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Loan repurchase commitments |  | 418 | 407 |
International And Structured Finance Insurance [Member] | Non Variable Interest Entity [Member] |  |  |  |
Loss And Loss Adjustment Expense Reserves [Line Items] |  |  |  |
Insurance Loss Recoverable |  | 993 | 178 |
Loss and loss adjustment expense reserves |  | $ 383 | $ 467 |
[1] | Includes loan repurchase commitments of $418 million and $407 million as of December, 2018 and December 31, 2017, respectively.

X
- Definition Carrying amount as of the balance sheet date of paid insurance policy claims and LAE expense expected to be recovered. + References No definition available. + Details
Name: | mbi_InsuranceLossRecoverable
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The fair value of financial instruments that represent the right of the Trust against the seller/servicer for loans that were not compliant with the representations and warranties of the loan underwriting. The Trust has the right to demand that the transferor replace ineligible loans with a compliant loan or repurchase the non-compliant loan. + References No definition available. + Details
Name: | mbi_LoanRepurchaseCommitments
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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 The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99382578&loc=d3e14764-158437 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (cc) -URI http://asc.fasb.org/extlink&oid=99382578&loc=d3e14764-158437 + Details
Name: | us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | mbi_ClaimLiabilityAxis=mbi_LossAndLaeReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mbi_ClaimLiabilityAxis=mbi_InsuranceLossRecoverableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=mbi_InternationalAndStructuredFinanceInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | mbi_ClaimLiabilityAxis=mbi_LoanRepurchaseCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=srt_ConsolidatedEntityExcludingVariableInterestEntitiesVIEMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |