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, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Loans	$ 2,228	$ 1,904
Investment Securities	512	493
Borrowed Funds	344	240
Other	245	301
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Us Treasury And Government And Other Debt Securities [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(90)	(21)
Derivatives	92	22
Amounts related to interest settlements on derivatives	(3)	(15)
Fair Value Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Subordinated debt and Bank notes and senior debt [Member] \| Borrowed Funds Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	370	86
Derivatives	(370)	(95)
Amounts related to interest settlements on derivatives	26	76
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Loans Receivable [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from accumulated OCI	26	46
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Other [Member] \| Noninterest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from accumulated OCI	2	3
Cash Flow Hedging [Member] \| Designated as Hedging Instrument [Member] \| Interest Rate Contracts [Member] \| Investment Securities [Member] \| Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of derivative gains (losses) reclassified from accumulated OCI	$ 4	$ 6

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 25
-Section 50
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