Financial Derivatives (Gains (Losses) Recognized on Fair Value and Cash Flow Hedges in Consolidated Income Statement) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Loans, interest income	$ 9,007	$ 8,927	$ 10,525
Investment securities, interest income	1,834	2,041	2,426
Borrowed funds, interest expense	361	718	1,811
Total noninterest income	8,564	6,955	6,874
Other
Derivative Instruments, Gain (Loss) [Line Items]
Total noninterest income	1,840	1,364	1,473
Fair Value Hedging \| Designated as Hedging Instrument \| Investment Securities \| Investment Securities Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on related hedged items recognized in income	(5)	208	187
Gain (loss) on derivatives recognized in income	9	(202)	(178)
Interest settlements on derivatives	(4)	(9)	13
Fair Value Hedging \| Designated as Hedging Instrument \| Borrowed Funds \| Borrowed Funds Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on related hedged items recognized in income	937	(1,059)	(808)
Gain (loss) on derivatives recognized in income	(993)	959	659
Interest settlements on derivatives	521	480	79
Cash Flow Hedging \| Designated as Hedging Instrument \| Loans \| Investment Securities Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	376	375	9
Cash Flow Hedging \| Designated as Hedging Instrument \| Investment Securities \| Investment Securities Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	57	40	9
Cash Flow Hedging \| Designated as Hedging Instrument \| Other Income \| Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	$ 61	$ 6	$ 19

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Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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