XML 82 R59.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Insurance Premiums (Unearned Premium Revenue Balance And Future Expected Earnings) (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014
--- | ---
Insurance Premiums [Line Items] |
Three months ended, March 31, 2015, Total Expected Future Premium Earnings | $ 58 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFirstQuarterFollowingBalanceSheetDate
Three months ended, June 30, 2015, Total Expected Future Premium Earnings | 57 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSecondQuarterFollowingBalanceSheetDate
Three months ended, September 30, 2015, Total Expected Future Premium Earnings | 55 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringThirdQuarterFollowingBalanceSheetDate
Three months ended, December 31, 2015, Total Expected Future Premium Earnings | 54 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFourthQuarterFollowingBalanceSheetDate
Twelve months ended, December 31, 2016, Total Expected Future Premium Earnings | 204 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate
Twelve months ended, December 31, 2017, Total Expected Future Premium Earnings | 187 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate
Twelve months ended, December 31, 2018, Total Expected Future Premium Earnings | 168 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanThreeAndWithinFourYearsFromBalanceSheetDate
Twelve months ended, December 31, 2019, Total Expected Future Premium Earnings | 155 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanFourAndWithinFiveYearsFromBalanceSheetDate
Five years ended, December 31, 2024, Total Expected Future Premium Earnings | 599 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixthThroughTenthYearFollowingBalanceSheetDate
Five years ended, December 31, 2029, Total Expected Future Premium Earnings | 362 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringEleventhThroughFifteenthYearFollowingBalanceSheetDate
Five years ended, December 31, 2034 and thereafter, Total Expected Future Premium Earnings | 323 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixteenthYearAndThereafterFollowingBalanceSheetDate
Total Expected Future Premium Earnings | 2,222 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognized
Unearned Premium Revenue [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,986 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember
Unearned Premium Revenue [Member] | March Thirty One Two Thousand Fifeteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,934 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_MarchThirtyOneTwoThousandFifteenMember
Unearned Premium Revenue [Member] | June Thirty Two Thousand Fifeteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,883 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_JuneThirtyTwoThousandFifeteenMember
Unearned Premium Revenue [Member] | September Thirty Two Thousand Fifeteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,834 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_SeptemberThirtyTwoThousandFifeteenMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Fifeteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,786 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandFifeteenMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Sixteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,603 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandSixteenrMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Seventeen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,436 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandSeventeenMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Eighteen [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,286 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandEighteenMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Nineteen [Member] [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 1,148 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandTwentyNineteenMemberMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Four [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 613 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandTwentyFourMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Twenty Nine[Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 288 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandTwentyNineMember
Unearned Premium Revenue [Member] | December Thirty One Two Thousand Thirty Four And Thereafter [Member] |
Insurance Premiums [Line Items] |
Unearned Premiums | 0 us-gaap_UnearnedPremiums / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UnearnedPremiumRevenueMember / us-gaap_StatementScenarioAxis = mbi_DecemberThirtyOneTwoThousandThirtyFourAndThereafterMember
Upfront [Member] |
Insurance Premiums [Line Items] |
Three months ended, March 31, 2015, Total Expected Future Premium Earnings | 30 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFirstQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Three months ended, June 30, 2015, Total Expected Future Premium Earnings | 29 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSecondQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Three months ended, September 30, 2015, Total Expected Future Premium Earnings | 28 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringThirdQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Three months ended, December 31, 2015, Total Expected Future Premium Earnings | 27 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFourthQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Twelve months ended, December 31, 2016, Total Expected Future Premium Earnings | 102 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Twelve months ended, December 31, 2017, Total Expected Future Premium Earnings | 93 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Twelve months ended, December 31, 2018, Total Expected Future Premium Earnings | 85 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanThreeAndWithinFourYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Twelve months ended, December 31, 2019, Total Expected Future Premium Earnings | 78 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanFourAndWithinFiveYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Five years ended, December 31, 2024, Total Expected Future Premium Earnings | 294 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixthThroughTenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Five years ended, December 31, 2029, Total Expected Future Premium Earnings | 171 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringEleventhThroughFifteenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Five years ended, December 31, 2034 and thereafter, Total Expected Future Premium Earnings | 146 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixteenthYearAndThereafterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Total Expected Future Premium Earnings | 1,083 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognized / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_UpfrontMember
Installments [Member] |
Insurance Premiums [Line Items] |
Three months ended, March 31, 2015, Total Expected Future Premium Earnings | 22 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFirstQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Three months ended, June 30, 2015, Total Expected Future Premium Earnings | 22 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSecondQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Three months ended, September 30, 2015, Total Expected Future Premium Earnings | 21 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringThirdQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Three months ended, December 31, 2015, Total Expected Future Premium Earnings | 21 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFourthQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Twelve months ended, December 31, 2016, Total Expected Future Premium Earnings | 81 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Twelve months ended, December 31, 2017, Total Expected Future Premium Earnings | 74 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Twelve months ended, December 31, 2018, Total Expected Future Premium Earnings | 65 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanThreeAndWithinFourYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Twelve months ended, December 31, 2019, Total Expected Future Premium Earnings | 60 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanFourAndWithinFiveYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Five years ended, December 31, 2024, Total Expected Future Premium Earnings | 241 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixthThroughTenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Five years ended, December 31, 2029, Total Expected Future Premium Earnings | 154 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringEleventhThroughFifteenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Five years ended, December 31, 2034 and thereafter, Total Expected Future Premium Earnings | 142 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixteenthYearAndThereafterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Total Expected Future Premium Earnings | 903 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognized / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_InstallmentsMember
Accretion [Member] |
Insurance Premiums [Line Items] |
Three months ended, March 31, 2015, Total Expected Future Premium Earnings | 6 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFirstQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Three months ended, June 30, 2015, Total Expected Future Premium Earnings | 6 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSecondQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Three months ended, September 30, 2015, Total Expected Future Premium Earnings | 6 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringThirdQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Three months ended, December 31, 2015, Total Expected Future Premium Earnings | 6 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringFourthQuarterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Twelve months ended, December 31, 2016, Total Expected Future Premium Earnings | 21 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Twelve months ended, December 31, 2017, Total Expected Future Premium Earnings | 20 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Twelve months ended, December 31, 2018, Total Expected Future Premium Earnings | 18 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanThreeAndWithinFourYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Twelve months ended, December 31, 2019, Total Expected Future Premium Earnings | 17 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedMoreThanFourAndWithinFiveYearsFromBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Five years ended, December 31, 2024, Total Expected Future Premium Earnings | 64 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixthThroughTenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Five years ended, December 31, 2029, Total Expected Future Premium Earnings | 37 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringEleventhThroughFifteenthYearFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Five years ended, December 31, 2034 and thereafter, Total Expected Future Premium Earnings | 35 mbi_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognizedDuringSixteenthYearAndThereafterFollowingBalanceSheetDate / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember
Total Expected Future Premium Earnings | $ 236 us-gaap_FinancialGuaranteeInsuranceContractsFutureExpectedPremiumRevenueToBeRecognized / us-gaap_DeferredRevenueArrangementTypeAxis = mbi_AccretionMember

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
- 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 contracts expected to be recognized in the next fiscal quarter following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the fourth fiscal quarter following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the second fiscal quarter following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the third fiscal quarter following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the fifth fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the second fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the fourth fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 contracts expected to be recognized in the third fiscal year following the latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 16 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13 -Subparagraph a(2) -Article 7 + 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_AccretionMember
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_UnearnedPremiumRevenueMember
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: |