Debt Instrument Amount Payable On Repurchase

No definition available.

Name:	mbi_DebtInstrumentAmountPayableOnRepurchase
Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument, call date for first fifth anniversary.

+ References

No definition available.

+ Details

Name:	mbi_DebtInstrumentCallDateForFirstFifthAnniversary
Namespace Prefix:	mbi_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument maturity year.

+ References

No definition available.

+ Details

Name:	mbi_DebtInstrumentMaturityYear
Namespace Prefix:	mbi_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

long-term debt principal amount previously purchased.

+ References

No definition available.

+ Details

Name:	mbi_LongTermDebtPrincipalAmountPreviouslyPurchased
Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

Name:	us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentageOfPrincipalAmountRedeemed
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The cash inflow from a borrowing where a lender is placed in a lien position behind debt having a higher priority of repayment (senior) in liquidation of the entity's assets or underlying collateral.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	mbi_DebtInstrumentOneAxis=mbi_MbiaIncDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_MbiaincSeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_MbiaCorpSurplusNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_MbiaIncDebenturesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_SixPointFourZeroZeroPercentageSeniorNotesDueTwoThousandTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_SixPointSixTwoFivePercentageDebenturesDueTwoThousandTwentyEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mbi_SevenPointOneFiveZeroPercentageDebenturesDueTwoThousandTwentySevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_MediumTermNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	mbi_InterestRateTypeAxis=mbi_FloatingRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=mbi_InvestmentAgreementObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=mbi_RefinancedFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_MBIACorpFinancingFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=mbi_InitialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=mbi_OutstandingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_MbiaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_NationalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_MbiaCorpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_VariableInterestEntityPrimaryBeneficiaryAggregatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=mbi_MbiaInsuredVariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
Debt (Narrative) (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Aggregate unpaid contractual principal	$ 2,331	$ 2,229
Debt instrument principal amount repurchased	$ 308
Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	7.00%
Long-term debt, maturity year	2025
MBIA Inc. Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.70%
Long-term debt, maturity year	2034
Debt instrument principal amount repurchased	$ 10
Debt instrument amount payable on repurchase	$ 10
MBIA Corp Surplus Notes [Member]
Debt Instrument [Line Items]
Callable date for fifth anniversary of initial callable date	Jan. 15, 2023
Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	7.00%
Long-term debt, maturity year	2025
Debt instrument principal amount repurchased	$ 13
6.400% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Percentage of debt redemption		100.00%
Debt instrument interest rate	6.40%	6.40%
Long-term debt, maturity year	2022
Long-term debt principal amount previously purchased		$ 115
Debt instrument principal amount repurchased	$ 115
6.625% Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	6.625%
Long-term debt, maturity year	2028
Aggregate unpaid contractual principal	$ 136	141
7.150% Debentures Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	7.15%
Long-term debt, maturity year	2027
Aggregate unpaid contractual principal	$ 99	$ 100
Medium-term notes [Member]
Debt Instrument [Line Items]
Weighted average interest rate	3.62%	2.97%
Medium-term notes [Member] \| Floating Rate [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	0.00%
Investment Agreement Obligations [Member]
Debt Instrument [Line Items]
Weighted average interest rate	5.89%	5.86%
Refinanced Facility [Member]
Debt Instrument [Line Items]
Proceeds from issuance of senior notes			$ 54
Debt instrument interest rate	7.00%
Long-term debt, maturity date	Apr. 20, 2022
Aggregate unpaid contractual principal	$ 68
Maximum [Member] \| Medium-term notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.90%	6.00%
Maximum [Member] \| Investment Agreement Obligations [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	6.88%	6.88%
Minimum [Member] \| Medium-term notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	0.00%	0.00%
Minimum [Member] \| Investment Agreement Obligations [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.78%	4.78%
MBIA Corp Financing Facility [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	12.00%
Long-term debt, maturity date	Jan. 20, 2022
MBIA Corp Financing Facility [Member] \| Initial [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal			$ 278
MBIA Corp Financing Facility [Member] \| Outstanding [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal		$ 273
Mbia Inc [Member] \| MBIA Corp Surplus Notes [Member]
Debt Instrument [Line Items]
Long-term debt principal amount previously purchased	$ 13
National [Member] \| Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Long-term debt principal amount previously purchased	308
Debt instrument principal amount repurchased	10
Mbia Corp [Member] \| 6.625% Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	5
Mbia Corp [Member] \| 7.150% Debentures Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	1
Variable Interest Entity Primary Beneficiary [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal	922	1,400
MBIA Insured Variable Interest Entity Primary Beneficiary [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal	$ 350	$ 722