Financial Derivatives (Gains (Losses) Recognized on Fair Value and Cash Flow Hedges in the Consolidated Income Statement) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Loans	$ 2,480	$ 2,602
Investment Securities	582	620
Borrowed Funds	314	481
Other	343	308
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Borrowed Funds [Member] \| Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(1,361)	(274)
Derivatives	1,339	228
Amounts related to interest settlements on derivatives	59	11
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Investment Securities [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	234	58
Derivatives	(231)	(55)
Amounts related to interest settlements on derivatives	(2)	5
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Loans [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	42	(8)
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Other [Member] \| Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	1	15
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Investment Securities [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from AOCI	$ 2	$ 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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