XML 44 R37.htm IDEA: XBRL DOCUMENT v3.25.1

Variable Interest Entities (Narrative) (Detail) - VariableInterestEntities	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Variable Interest Entity, Primary Beneficiary [Member] | Structured Finance and International Insurance [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities consolidated	0	0

X

- Definition

Number of variable interest entities consolidated.

+ References

No definition available.

+ Details

Name:	mbi_NumberOfVariableInterestEntitiesConsolidated
Namespace Prefix:	mbi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481203/810-10-50-3

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481231/810-10-45-25

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (bb)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481203/810-10-50-3

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 810
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 25
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481231/810-10-45-25

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481420/860-30-50-1A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481420/860-30-50-1A

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 860
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481420/860-30-50-1A

+ Details

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

X

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=mbi_StructuredFinanceAndInternationalInsuranceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: