Derivative Financial Instruments (Effect of Derivative Instruments on the Consolidated Statements of Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	$ (36)	$ (90)	$ (44)	$ (81)
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	10	8	19	14
Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Interest Income [Member]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	(4)	(6)	(8)	(13)
Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	14	14	27	27
Net Investment Hedging [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	1	(1)	0	(3)
Fair Value Hedges [Member] | Interest Rate Contract [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	98	87	164	126
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Interest Income [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(5)	(5)	(10)	(10)
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	103	92	174	136
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	147	60	159	(40)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Interest Rate Contract [Member] | Other Income [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	11	1	17	(2)
Not Designated as Hedging Instrument [Member] | Client-Related and Other Risk Management [Member] | Foreign Exchange Contract [Member] | Other Income [Member]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	2	2	4	4
Not Designated as Hedging Instrument [Member] | Mortgage Banking [Member] | Interest Rate Contract [Member] | Mortgage Banking Income [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(18)	(2)	39	(62)
Not Designated as Hedging Instrument [Member] | Mortgage Servicing Rights [Member] | Interest Rate Contract [Member] | Mortgage Banking Income [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ 152	$ 59	$ 99	$ 20