Fair Value Option - Components of Gain (Loss) on Instruments at Fair Value and Related Derivatives (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]
Mark-to-market on related derivatives	$ (220)	$ (181)
Gain (loss) on instruments designated at fair value and related derivatives	(5)	(3)
Gain (loss) on instruments designated at fair value and related derivatives
Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]
Interest rate and other components	206	172
Credit risk component, total	(2)	(7)
Total mark-to-market on financial instruments designated at fair value	204	165
Mark-to-market on related derivatives	(209)	(168)
Gain (loss) on instruments designated at fair value and related derivatives	(5)	(3)
Gain (loss) on instruments designated at fair value and related derivatives \| Loans
Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]
Interest rate and other components	0	0
Credit risk component, assets	(2)	(7)
Total mark-to-market on financial instruments designated at fair value	(2)	(7)
Mark-to-market on related derivatives	0	0
Gain (loss) on instruments designated at fair value and related derivatives	(2)	(7)
Gain (loss) on instruments designated at fair value and related derivatives \| Long-term debt
Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]
Interest rate and other components	5	(16)
Credit risk component, liabilities	0	0
Total mark-to-market on financial instruments designated at fair value	5	(16)
Mark-to-market on related derivatives	(4)	18
Gain (loss) on instruments designated at fair value and related derivatives	1	2
Gain (loss) on instruments designated at fair value and related derivatives \| Hybrid Instruments
Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]
Interest rate and other components	201	188
Credit risk component, liabilities	0	0
Total mark-to-market on financial instruments designated at fair value	201	188
Mark-to-market on related derivatives	(205)	(186)
Gain (loss) on instruments designated at fair value and related derivatives	$ (4)	$ 2

Components Of Gain On Instruments At Fair Value And Related Derivatives [Line Items]

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Fair Value, Option, Credit Risk, Gains (Losses), Net

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Fair Value, Option, Interest Rate And Other Components, Gains (Losses)

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Fair value changes on fixed rate debt, loans and certain other financial instruments accounted for under fair value option as well as the fair value changes on the related derivatives and realized gains (losses) on the debt related derivatives.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

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This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets.

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Amount, before tax, after reclassification adjustment, of gain (loss) from increase (decrease) in instrument-specific credit risk of financial liability measured under fair value option.

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