Fair Value (Level 3 Total Realized And Unrealized Gains And Losses Recorded In Revenue) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Total Revenue [Member]
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	$ 49	$ 155
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	4
Trading services
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	34	9
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	4
Total fee revenue
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	34	9
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	4
Net interest revenue
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	15	146
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	$ 0	$ 0