Thus element represents the aggregate amounts of claim paid to date

No definition available.

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

- Definition

This element represents the gross amount of claim payments during the period

+ References

No definition available.

+ Details

Name:	mbi_ClaimPayments
Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

Increase in lquidity during the period

+ References

No definition available.

+ Details

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Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

- Definition

This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(b))
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-Subparagraph (SX 210.9-06)
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Balance Type:	debit
Period Type:	duration

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of warrants or rights outstanding.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

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

+ References

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

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

- Definition

Number of treasury shares (units) reissued during the period, excluding reissuance of shares (units) held in treasury used to satisfy equity-based compensation obligations exercised by the holders of such rights. Upon reissuance of shares (units) from treasury, either the common or preferred stock (unit) reissued is outstanding.

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-SubTopic 10
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

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Business Developments And Risks And Uncertainties (Narrative) (Detail) $ / shares in Units, $ in Millions			9 Months Ended
	Nov. 02, 2018 USD ($)	Oct. 11, 2018 USD ($)	Sep. 30, 2018 USD ($) segments $ / shares shares
Business Acquisition [Line Items]
Number of operating segments \| segments			3
Warrants outstanding \| shares			11,850,000
Warrant exercise price \| $ / shares			$ 9.59
Treasury shares issued (in shares) \| shares			1,300,000
Zohar [Member]
Business Acquisition [Line Items]
Aggregate claim amount			$ 919
Puerto Rico [Member]
Business Acquisition [Line Items]
Claims payments			$ 276
SubsequentEvent [Member]
Business Acquisition [Line Items]
Increase in MBIA Inc's liquidity	$ 41
National [Member] \| SubsequentEvent [Member]
Business Acquisition [Line Items]
Dividends from subsidiaries		$ 108
MBIA Inc. Senior Notes [Member] \| SubsequentEvent [Member]
Business Acquisition [Line Items]
Long-term debt, interest rate	5.70%
Long-term debt, maturity year	2034
Mbia Inc. Debentures [Member] \| SubsequentEvent [Member]
Business Acquisition [Line Items]
Long-term debt, interest rate	7.00%
Long-term debt, maturity year	2025