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Contracts Accounted for as Credit Derivatives - Credit Derivatives Subordination and Ratings (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Credit Derivatives |  |
Estimated remaining weighted average life of credit derivatives (in years) | 8 years 10 months 24 days | 8 years 4 months 24 days
Net Par Outstanding on Credit Derivatives |  |
Net Par Outstanding | $ 3,759 | $ 4,212
Net Fair Value Asset (Liability) | (26) | (29)
Public finance | United States |  |
Net Par Outstanding on Credit Derivatives |  |
Net Par Outstanding | 997 | 1,025
Net Fair Value Asset (Liability) | (11) | (12)
Public finance | Non United States |  |
Net Par Outstanding on Credit Derivatives |  |
Net Par Outstanding | 1,645 | 2,044
Net Fair Value Asset (Liability) | (14) | (15)
Structured finance | United States |  |
Net Par Outstanding on Credit Derivatives |  |
Net Par Outstanding | 143 | 150
Net Fair Value Asset (Liability) | (2) | (2)
Structured finance | Non United States |  |
Net Par Outstanding on Credit Derivatives |  |
Net Par Outstanding | 974 | 993
Net Fair Value Asset (Liability) | $ 1 | $ 0

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- Definition Average period covered by credit risk derivative contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4K -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4K + Details
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