Debt (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Debt instrument interest rate	18.00%
Long-term debt, maturity date	Aug. 02, 2027
Aggregate unpaid contractual principal	$ 2,428	$ 2,331
Debt instrument principal amount repurchased	308
Repayments of Debt	7
Unfunded Loan Commitment [Member]
Debt Instrument [Line Items]
Other Commitment	$ 8
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
MBIA Corp Surplus Notes [Member]
Debt Instrument [Line Items]
Callable date for fifth anniversary of initial callable date	Jan. 15, 2028
MBIA Corp Surplus Notes [Member] \| Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	$ 13
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	$ 112	136
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	$ 96	99
Third Party Loan [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal	$ 2
7.000% Debentures Due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	7.00%
Long-term debt, maturity year	2025
Aggregate unpaid contractual principal	$ 45	$ 46
Medium-term notes [Member]
Debt Instrument [Line Items]
Weighted average interest rate	4.65%	3.62%
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	6.09%	5.89%
Maximum [Member] \| Medium-term notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.90%	5.90%
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	2.06%	0.00%
Minimum [Member] \| Investment Agreement Obligations [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.78%	4.78%
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]
Debt instrument principal amount repurchased	10
National [Member] \| MBIA Inc. Senior Notes [Member] \| Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	10
Debt instrument amount payable on repurchase	10
National [Member] \| Mbia Inc Debentures [Member]
Debt Instrument [Line Items]
Long-term debt principal amount previously purchased	308
Mbia Corp [Member] \| 6.625% Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	24	$ 5
Mbia Corp [Member] \| 7.150% Debentures Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument principal amount repurchased	4	1
Mbia Corp [Member] \| 7.000% Debentures Due 2025 [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	780	922
MBIA Insured Variable Interest Entity Primary Beneficiary [Member]
Debt Instrument [Line Items]
Aggregate unpaid contractual principal	$ 189	$ 350

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)
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-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

+ Details

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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)
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-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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-Publisher FASB
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-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_UnfundedLoanCommitmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- 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

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

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

- Details

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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:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	srt_RangeAxis=srt_MinimumMember
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:	us-gaap_DebtInstrumentAxis=mbi_MbiaIncDebenturesMember
Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
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- Details

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