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Derivative Instruments and Hedging Activities - Gains (Losses) on Accounting Hedges and Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Investment Securities - AFS
Fair Value Hedges - Hedged Items
Amortized cost basis currently/ carrying amount currently or previously hedged	$ 11,039		$ 17,902
Basis adjustments included in carrying amount	(840)		(591)
Deposits
Fair Value Hedges - Hedged Items
Amortized cost basis currently/ carrying amount currently or previously hedged	4,807		6,279
Basis adjustments included in carrying amount	(83)		5
Borrowings
Borrowings
Carrying amount currently or previously hedged	122,770		122,919
Basis adjustments included in carrying amount—Outstanding hedges	(3,831)		2,324
Basis adjustments included in carrying amount—Terminated hedges	(736)		$ (743)
Fair Value Hedges \| Interest Income \| Interest rate contracts
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense
Gains (losses) recognized in Interest Expense	795	$ 831
Fair Value Hedges \| Interest Income \| Investment Securities - AFS
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense
Gains (losses) recognized in Interest Expense	(751)	(772)
Fair Value Hedges \| Interest expense \| Interest rate contracts
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense
Gains (losses) recognized in Interest Expense	(6,233)	(4,108)
Fair Value Hedges \| Interest expense \| Deposits
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense
Gains (losses) recognized in Interest Expense	88	36
Fair Value Hedges \| Interest expense \| Borrowings
Gain (Loss) on Fair Value Hedges Recognized in Interest Expense
Gains (losses) recognized in Interest Expense	6,155	4,021
Net Investment Hedges \| Foreign exchange
Net Investment Hedges
Recognized in OCI	139	405
Forward points excluded from hedge effectiveness testing—Recognized in Interest income	$ (41)	$ 1