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Fair Value of Financial Instruments (Narrative) (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Percentage of level 3 assets at fair value in total assets measured at fair value value | 6.00% |  | 6.00% |  | 7.00%
Percentage of level 3 liabilities at fair value in total liabilities measured at fair value | 85.00% |  | 85.00% |  | 82.00%
Gain (loss) on cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option | $ (263) |  | $ (263) |  | $ (283)
Instrument-specific credit risk of liabilities measured at fair value, net [Member] |  |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |  |  |  |
Gain (loss) on cumulative changes in instrument-specific credit risk of liabilities elected under the fair value option | (4) |  | (4) |  | $ (45)
Gain (loss) on instrument-specific credit risk recognized in earnings | $ (11) | $ (23) | $ (45) | $ (11) |

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