Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Basic earnings per share
Net income	$ 4,924	$ 5,555
Less: Preferred stock dividends	157	157
Net income applicable to common equity	4,767	5,398
Less: Dividends and undistributed earnings allocated to participating securities	190	262
Net income applicable to common stockholders	4,577	5,136
Total weighted-average basic shares outstanding	3,818.8	3,981.6
Net income per share	$ 1.20	$ 1.29
Diluted earnings per share
Net income applicable to common stockholders	$ 4,577	$ 5,136
Total weighted-average basic shares outstanding	3,818.8	3,981.6
Add: Employee stock options, SARs and warrants	14.6	32.5
Total weighted-average diluted shares outstanding	3,833.4	4,014.1
Net income per share	$ 1.19	$ 1.28
Earnings per share (Numeric) [Abstract]
Antidilutive options and warrants excluded from the computation of diluted EPS	169	85