Derivative Instruments and Hedging Activities - Gains (Losses) on Accounting Hedges and Fair Value Hedges (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash Flow Hedges - Interest Rate Contracts Recognized in Interest Income
Recognized in OCI	$ (19)	$ (100)	$ 9
Less: Realized gains (losses) (pre-tax) reclassified from AOCI to interest income	(95)	(32)	(16)
Net change in cash flow hedges included within AOCI	76	(68)	25
Cash flow hedges expected to be reclassified from AOCI	(68)
Borrowings
Amortized cost	589	325
Hedged asset, excluded from amortized cost	703	178
Amortized cost, unallocated basis adjustment	2	$ (2)
Interest rate
Cash Flow Hedges - Interest Rate Contracts Recognized in Interest Income
Maximum length of time over which forecasted cash flows are hedged		40 months
Investment securities—AFS
Investment Securities—AFS and Deposits
Amortized cost basis currently/ carrying amount currently or previously hedged	55,451	$ 54,809
Basis adjustments included in amortized cost/ carrying amount	217	(741)
Deposits
Investment Securities—AFS and Deposits
Amortized cost basis currently/ carrying amount currently or previously hedged	53,224	21,524
Basis adjustments included in amortized cost/ carrying amount	149	44
Borrowings
Borrowings
Carrying amount currently or previously hedged	199,274	171,834
Basis adjustments included in carrying amount—Outstanding hedges	(6,252)	(10,072)
Basis adjustments included in carrying amount—Terminated hedges	(625)	(648)
Fair Value Hedges \| Interest Income \| Interest rate
Gain (Loss) on Fair Value Hedges Recognized in Interest Income / Expense
Gains (losses) recognized in Interest Income / Expense	(895)	291	(576)
Fair Value Hedges \| Interest Income \| Investment securities—AFS
Gain (Loss) on Fair Value Hedges Recognized in Interest Income / Expense
Gains (losses) recognized in Interest Income / Expense	943	(204)	638
Fair Value Hedges \| Interest Expense \| Interest rate
Gain (Loss) on Fair Value Hedges Recognized in Interest Income / Expense
Gains (losses) recognized in Interest Income / Expense	3,982	(822)	3,664
Fair Value Hedges \| Interest Expense \| Deposits
Gain (Loss) on Fair Value Hedges Recognized in Interest Income / Expense
Gains (losses) recognized in Interest Income / Expense	(105)	(75)	(88)
Fair Value Hedges \| Interest Expense \| Borrowings
Gain (Loss) on Fair Value Hedges Recognized in Interest Income / Expense
Gains (losses) recognized in Interest Income / Expense	(3,883)	889	(3,564)
Net Investment Hedges \| Foreign exchange
Net Investment Hedges
Recognized in OCI	(1,041)	1,084	(168)
Forward points excluded from hedge effectiveness testing—Recognized in Interest income	$ 199	$ 214	$ 211

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Derivative Instruments, Gain (Loss) Recognized In Other Comprehensive Income (Loss)

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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