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Commitments, Contingencies, And Guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | $ 23 | $ 54 | $ (158) | $ (178)
Foreign currency forward contracts |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 52 | (17) | (28) | (95)
Options/Futures contracts on notes and bonds |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 12 | 29 | 30 | 5
Convertible securities |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative | [1] | 2 | (3) | 4 | (2)
Investment And Embedded Derivative Instruments [Member] |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 66 | 9 | 6 | (92)
Futures contracts on equities |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative | [2] | (41) | 52 | (157) | (80)
Other derivative instruments |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | (2) | (7) | (7) | (6)
Other Derivative Instruments [Member] |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | $ (43) | $ 45 | $ (164) | $ (86)
[1] | Includes embedded derivatives.
[2] | Related to MRB book of business.

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A + Details
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