Derivative Financial Instruments (Effect of Derivative Instruments on the Consolidated Statements of Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	$ (8)	$ 9
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	9	6
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)	(7)
Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	13	13
Net Investment Hedging [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	(1)	(2)
Fair Value Hedges [Member] | Interest Rate Contract [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	66	39
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Interest Income [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	(5)	(5)
Fair Value Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	71	44
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	12	(100)
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	6	(3)
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
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	57	(60)
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	$ (53)	$ (39)