Earnings Per Share (Details) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Basic earnings per share
Net income	$ 4,262	$ 4,418	$ 15,248	$ 12,539
Less: Preferred stock dividends	157	160	472	485
Net income applicable to common equity	4,105	4,258	14,776	12,054
Less: Dividends and undistributed earnings allocated to participating securities	169	239	635	701
Net income applicable to common stockholders	3,936	4,019	14,141	11,353
Total weighted-average basic shares outstanding	3,859.6	3,954.3	3,933.2	3,969.4
Net income per share	$ 1.02	$ 1.02	$ 3.60	$ 2.86
Diluted earnings per share
Net income applicable to common stockholders	$ 3,936	$ 4,019	$ 14,141	$ 11,353
Total weighted-average basic shares outstanding	3,859.6	3,954.3	3,933.2	3,969.4
Add: Employee stock options, SARs and warrants	12.6	17.6	23.3	21.3
Total weighted-average diluted shares outstanding	3,872.2	3,971.9	3,956.5	3,990.7
Net income per share	$ 1.02	$ 1.01	$ 3.57	$ 2.84
Earnings per share (Numeric) [Abstract]
Antidilutive options and warrants excluded from the computation of diluted EPS	197	236	112	233