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Insurance in Force (Narrative) (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2024 | Dec. 31, 2023
Guarantor Obligations [Line Items] |  |
Transactions guaranteed by MBIA on behalf of affiliated companies | $ 900 |
Aggregate amount of insurance in force ceded to reinsurers | 1,500 | $ 1,700
Aggregate amount of insured par outstanding ceded to reinsurers | 671 | $ 782
US Public Finance Insurance [Member] |  |
Guarantor Obligations [Line Items] |  |
Aggregate amount of insured par outstanding ceded to reinsurers | 539 |
Structured Finance And International Insurance [Member] |  |
Guarantor Obligations [Line Items] |  |
Aggregate amount of insured par outstanding ceded to reinsurers | $ 132 |
Financial Guaranty Insurance Company [Member] |  |
Guarantor Obligations [Line Items] |  |
Financial guaranty maturity year | 2058 |
Investment agreements, MTNs and other affiliated contracts [Member] |  |
Guarantor Obligations [Line Items] |  |
Financial guaranty maturity year | 2037 |

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- Definition Aggregate amount insurance in force outstanding ceded to reinsurers. + References No definition available. + Details
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- 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 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 460 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482425/460-10-50-4 + Details
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- Details
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- Details
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