Financial Derivatives (Gains (Losses) Recognized on Fair Value and Cash Flow Hedges in the Consolidated Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Loans	$ 2,160	$ 2,257	$ 4,156	$ 4,737
Investment Securities	469	527	890	1,109
Borrowed Funds	90	187	185	501
Noninterest income	2,086	1,549	3,958	3,374
Other
Derivative Instruments, Gain (Loss) [Line Items]
Noninterest income	468	271	951	614
Fair value hedges \| Designated as Hedging Instrument \| Investment Securities \| Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	3	3	(5)	237
Derivatives	(2)	(2)	7	(233)
Amounts related to interest settlements on derivatives	(1)	(2)	(2)	(4)
Fair value hedges \| Designated as Hedging Instrument \| Borrowed Funds \| Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(106)	(80)	540	(1,441)
Derivatives	93	47	(571)	1,386
Amounts related to interest settlements on derivatives	131	133	265	192
Cash flow hedges \| Designated as Hedging Instrument \| Loans \| Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	91	102	191	144
Cash flow hedges \| Designated as Hedging Instrument \| Investment Securities \| Interest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	16	1	38	3
Cash flow hedges \| Designated as Hedging Instrument \| Other \| Noninterest Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	$ 1		$ 14	$ 1

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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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The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases.

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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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