XML 72 R61.htm IDEA: XBRL DOCUMENT
v3.20.2

Derivative Instruments (Credit Derivatives Sold) (Detail) - Insurance Operations [Member] - USD ($) $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2020 | Dec. 31, 2019
Derivative [Line Items] |  |  |
Derivative notional amount | $ 1,826 | $ 1,957 |
Total fair value of credit derivatives | $ (10) | $ (9) |
Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Weighted average remaining expected maturity | 6 months | 1 year |
Derivative notional amount | $ 24 | $ 32 |
Total fair value of credit derivatives | $ (8) | $ (7) |
Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Weighted average remaining expected maturity | 14 years 2 months 12 days | 14 years |
Derivative notional amount | $ 1,802 | $ 1,925 | [1]
Total fair value of credit derivatives | (2) | (2) |
Credit Rating Aaa [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Total fair value of credit derivatives | 0 | 0 |
Credit Rating Aaa [Member] | Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Credit Rating Aaa [Member] | Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Credit Rating Aa [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 115 | 121 |
Total fair value of credit derivatives | 0 | 0 |
Credit Rating Aa [Member] | Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Credit Rating Aa [Member] | Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 115 | 121 | [2]
Credit Rating A [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 1,324 | 1,371 |
Total fair value of credit derivatives | (1) | (1) |
Credit Rating A [Member] | Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Credit Rating A [Member] | Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 1,324 | 1,371 | [3]
Credit Rating Bbb [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 363 | 433 |
Total fair value of credit derivatives | (1) | (1) |
Credit Rating Bbb [Member] | Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 0 | 0 |
Credit Rating Bbb [Member] | Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 363 | 433 | [4]
Credit Rating Below Investment Grade [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 24 | 32 |
Total fair value of credit derivatives | (8) | (7) |
Credit Rating Below Investment Grade [Member] | Credit Default Swap [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | 24 | 32 |
Credit Rating Below Investment Grade [Member] | Insured Swaps [Member] |  |  |
Derivative [Line Items] |  |  |
Derivative notional amount | $ 0 | $ 0 |
[1] | The Company revised its previously reported amount of $1,795 million to $1,925 million.
[2] | The Company revised its previously reported amount of $66 million to $121 million.
[3] | The Company revised its previously reported amount of $1,284 million to $1,371 million.
[4] | The Company revised its previously reported amount of $445 million to $433 million.

X
- Definition Weighted Average Remaining Maturity Credit Derivatives In Years + References No definition available. + Details
Name: | mbi_WeightedAverageRemainingMaturityCreditDerivativesInYears
Namespace Prefix: | mbi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value of credit risk derivative liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4K -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5708775-113959 + Details
Name: | us-gaap_CreditRiskDerivativeLiabilitiesAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal or face amount used to calculate payment on derivative. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959 + Details
Name: | us-gaap_DerivativeNotionalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_CreditDerivativesByContractTypeAxis=us-gaap_CreditDefaultSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditDerivativesByContractTypeAxis=mbi_InsuredSwapsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExternalCreditRatingByGroupingAxis=mbi_CreditRatingAaaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExternalCreditRatingByGroupingAxis=mbi_CreditRatingAaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExternalCreditRatingByGroupingAxis=mbi_CreditRatingAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExternalCreditRatingByGroupingAxis=mbi_CreditRatingBbbMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ExternalCreditRatingByGroupingAxis=mbi_CreditRatingBelowInvestmentGradeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |