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Financial Guarantees in Force - Summary of Financial Guarantee Portfolio Diversification by Type of Guaranteed Bond (Detail) - USD ($) $ in Millions | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | $ 22,613 | $ 28,020
Public Finance [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 10,547 | 12,360
Public Finance [Member] | Lease and Tax-backed Revenue [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,979 | 3,196
Public Finance [Member] | General Obligation [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,301 | 1,612
Public Finance [Member] | Housing Revenue [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 5,491 | 5,610
Public Finance [Member] | Other [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,776 | 1,942
Structured Finance [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 3,612 | 4,904
Structured Finance [Member] | Mortgage-backed and Home Equity [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,930 | 2,724
Structured Finance [Member] | Investor-owned Utilities [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,103 | 1,556
Structured Finance [Member] | Other Structured Finance [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 579 | 624
International Finance [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 8,454 | 10,756
International Finance [Member] | Asset Backed and Other [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 1,083 | 1,276
International Finance [Member] | Investor-owned and Public Utilities [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 2,583 | 3,283
International Finance [Member] | Sovereign/Sub-sovereign [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | 4,077 | 5,141
International Finance [Member] | Transportation [Member] |  |
Guarantor Obligations [Line Items] |  |
Net Par Amount Outstanding | $ 711 | $ 1,056

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- Definition Amount of participating insurance in force. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 50 -Section 50 -Paragraph 1 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451 + Details
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