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, 2013	Mar. 31, 2012
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ (46)	$ (53)
Cash Flow Hedges [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income, Effective Portion, Net	(11)	(13)
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	(21)	(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	0	4
Cash Flow Hedges [Member] | Interest Rate Contract [Member] | Interest Expense [Member]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	(21)	(18)
Fair Value Hedges [Member] | Interest Rate Contract [Member]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	25	70
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	30	75
Not Designated as Hedging Instrument [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	(64)	12
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	6
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	3	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	(27)	57
Not Designated as Hedging Instrument [Member] | Residential MSR [Member] | Interest Rate Contract [Member] | Mortgage Banking Income [Member]
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments	$ (46)	$ (53)