XML 68 R54.htm IDEA: XBRL DOCUMENT
v3.20.4

Insurance Premiums (Unearned Premium Revenue Balance And Future Expected Earnings) (Detail) $ in Millions | Dec. 31, 2020 USD ($)
--- | ---
Insurance Premiums [Line Items] |
Three months ending, March 31, 2021, Total Expected Future Premium Earnings | $ 14
Three months ending, June 30, 2021, Total Expected Future Premium Earnings | 14
Three months ending, September 30, 2021, Total Expected Future Premium Earnings | 14
Three months ending, December 31, 2021, Total Expected Future Premium Earnings | 13
Twelve months ending, December 31, 2022, Total Expected Future Premium Earnings | 50
Twelve months ending, December 31, 2023, Total Expected Future Premium Earnings | 43
Twelve months ending, December 31, 2024, Total Expected Future Premium Earnings | 40
Twelve months ending, December 31, 2025, Total Expected Future Premium Earnings | 35
Five years ending, December 31, 2030, Total Expected Future Premium Earnings | 115
Five years ending, December 31, 2035, Total Expected Future Premium Earnings | 63
Five years ending, December 31, 2040 and thereafter, Total Expected Future Premium Earnings | 59
Total Expected Future Premium Earnings | 460
Unearned Premium Revenue [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 405
Unearned Premium Revenue [Member] | March Thirty One Two Thousand Twenty One [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 392
Unearned Premium Revenue [Member] | June Thirty Two Thousand Twenty One [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 379
Unearned Premium Revenue [Member] | September Thirty Two Thousand Twenty One [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 367
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty One [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 355
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Two [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 310
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Three [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 271
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Four [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 235
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Five [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 204
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Thirty [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 104
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Thirty Five [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 50
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Fourty And Thereafter [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 0
Upfront [Member] |
Insurance Premiums [Line Items] |
Three months ending, March 31, 2021, Total Expected Future Premium Earnings | 6
Three months ending, June 30, 2021, Total Expected Future Premium Earnings | 6
Three months ending, September 30, 2021, Total Expected Future Premium Earnings | 6
Three months ending, December 31, 2021, Total Expected Future Premium Earnings | 6
Twelve months ending, December 31, 2022, Total Expected Future Premium Earnings | 21
Twelve months ending, December 31, 2023, Total Expected Future Premium Earnings | 19
Twelve months ending, December 31, 2024, Total Expected Future Premium Earnings | 17
Twelve months ending, December 31, 2025, Total Expected Future Premium Earnings | 15
Five years ending, December 31, 2030, Total Expected Future Premium Earnings | 50
Five years ending, December 31, 2035, Total Expected Future Premium Earnings | 24
Five years ending, December 31, 2040 and thereafter, Total Expected Future Premium Earnings | 16
Total Expected Future Premium Earnings | 186
Installments [Member] |
Insurance Premiums [Line Items] |
Three months ending, March 31, 2021, Total Expected Future Premium Earnings | 7
Three months ending, June 30, 2021, Total Expected Future Premium Earnings | 7
Three months ending, September 30, 2021, Total Expected Future Premium Earnings | 6
Three months ending, December 31, 2021, Total Expected Future Premium Earnings | 6
Twelve months ending, December 31, 2022, Total Expected Future Premium Earnings | 24
Twelve months ending, December 31, 2023, Total Expected Future Premium Earnings | 20
Twelve months ending, December 31, 2024, Total Expected Future Premium Earnings | 19
Twelve months ending, December 31, 2025, Total Expected Future Premium Earnings | 16
Five years ending, December 31, 2030, Total Expected Future Premium Earnings | 50
Five years ending, December 31, 2035, Total Expected Future Premium Earnings | 30
Five years ending, December 31, 2040 and thereafter, Total Expected Future Premium Earnings | 34
Total Expected Future Premium Earnings | 219
Accretion [Member] |
Insurance Premiums [Line Items] |
Three months ending, March 31, 2021, Total Expected Future Premium Earnings | 1
Three months ending, June 30, 2021, Total Expected Future Premium Earnings | 1
Three months ending, September 30, 2021, Total Expected Future Premium Earnings | 2
Three months ending, December 31, 2021, Total Expected Future Premium Earnings | 1
Twelve months ending, December 31, 2022, Total Expected Future Premium Earnings | 5
Twelve months ending, December 31, 2023, Total Expected Future Premium Earnings | 4
Twelve months ending, December 31, 2024, Total Expected Future Premium Earnings | 4
Twelve months ending, December 31, 2025, Total Expected Future Premium Earnings | 4
Five years ending, December 31, 2030, Total Expected Future Premium Earnings | 15
Five years ending, December 31, 2035, Total Expected Future Premium Earnings | 9
Five years ending, December 31, 2040 and thereafter, Total Expected Future Premium Earnings | 9
Total Expected Future Premium Earnings | $ 55

X
- Definition Financial guarantee insurance contracts, the amount of premium revenue expected to be recognized during the eleventh through fifteenth year following the statement of financial position reporting date + References No definition available. + Details
Name: | mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringEleventhThroughFifteenthYearFollowingBalanceSheetDate
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Financial guarantee insurance contracts, the amount of premium revenue expected to be recognized during the sixteenth year and thereafter following the statement of financial position reporting date. + References No definition available. + Details
Name: | mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixteenthYearAndThereafterFollowingBalanceSheetDate
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Financial guarantee insurance contracts, the amount of premium revenue expected to be recognized during the sixth through tenth year following the statement of financial position reporting date + References No definition available. + Details
Name: | mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixthThroughTenthYearFollowingBalanceSheetDate
Namespace Prefix: | mbi_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | mbi_InsurancePremiumsLineItems
Namespace Prefix: | mbi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of unearned premium revenue under contracts issued by an insurance entity that provide protection to the holder of a financial obligation from a financial loss in the event of a default. + References No definition available. + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in next fiscal quarter following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFirstQuarterFollowingBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in fourth fiscal quarter following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFourthQuarterFollowingBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in second fiscal quarter following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSecondQuarterFollowingBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in third fiscal quarter following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringThirdQuarterFollowingBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanFourAndWithinFiveYearsFromBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanThreeAndWithinFourYearsFromBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of premium revenue under financial guarantee insurance contract to be recognized in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6933581&loc=SL5749298-161291 + Details
Name: | us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(2)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
Name: | us-gaap_UnearnedPremiums
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DeferredRevenueArrangementTypeAxis=mbi_UnearnedPremiumRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_MarchThirtyOneTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_JuneThirtyTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_SeptemberThirtyTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandThirtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandTwentyThirtyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=mbi_DecemberThirtyOneTwoThousandFourtyAndThereafterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DeferredRevenueArrangementTypeAxis=mbi_UpfrontMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DeferredRevenueArrangementTypeAxis=mbi_InstallmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DeferredRevenueArrangementTypeAxis=mbi_AccretionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |