Derivative Financial Instruments (Effect of Derivative Instruments on the Consolidated Statements of Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	$ 251	$ (197)	$ 128
Cash Flow Hedges [Member] \| Interest Rate Contract [Member]
Derivative instruments, pre-tax gain (loss) recognized in OCI, effective portion, net	(172)	204	(84)
Derivative instruments, pre-tax gain (loss) reclassified from AOCI into income, effective portion, net	(82)	(77)	(61)
Cash Flow Hedges [Member] \| Interest Rate Contract [Member] \| Interest Income [Member]
Derivative instruments, pre-tax gain (loss) reclassified from AOCI into income, effective portion, net	0	0	11
Cash Flow Hedges [Member] \| Interest Rate Contract [Member] \| Interest Expense [Member]
Derivative instruments, pre-tax gain (loss) reclassified from AOCI into income, effective portion, net	(82)	(77)	(72)
Fair Value Hedges [Member] \| Interest Rate Contract [Member]
Derivative instruments, pre-tax gain (loss) recognized in income, net	211	120	267
Fair Value Hedges [Member] \| Interest Rate Contract [Member] \| Interest Income [Member]
Derivative instruments, pre-tax gain (loss) recognized in income, net	(22)	(21)	(21)
Fair Value Hedges [Member] \| Interest Rate Contract [Member] \| Interest Expense [Member]
Derivative instruments, pre-tax gain (loss) recognized in income, net	233	141	288
Not Designated as Hedging Instrument [Member]
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	269	(187)	231
Not Designated as Hedging Instrument [Member] \| Client-Related and Other Risk Management [Member] \| Interest Rate Contract [Member] \| Other Income [Member]
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	18	26	35
Not Designated as Hedging Instrument [Member] \| Client-Related and Other Risk Management [Member] \| Foreign Exchange Contract [Member] \| Other Income [Member]
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	16	11	9
Not Designated as Hedging Instrument [Member] \| Mortgage Banking [Member] \| Interest Rate Contract [Member] \| Mortgage Banking Income [Member]
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	(16)	(27)	59
Not Designated as Hedging Instrument [Member] \| MSRs [Member] \| Interest Rate Contract [Member] \| Mortgage Banking Income [Member]
Pre-tax gain (loss) on interest rate derivative instruments not designated as hedging instruments	$ 251	$ (197)	$ 128

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

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-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624177-113959

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The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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Amount of gain (loss) included in earnings for the period from the increase (decrease) in fair value of interest rate derivatives not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

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