Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share, Basic, Two Class Method [Abstract]
Net income	$ 21,284	$ 18,976	$ 17,370
Less: Preferred stock dividends	653	629	642
Net income applicable to common equity	20,631	18,347	16,728
Less: Dividends and undistributed earnings allocated to participating securities	754	779	964
Net income applicable to common stockholders	19,877	17,568	15,764
Total weighted-average basic shares outstanding	3,809.4	3,900.4	3,956.3
Net income per share	$ 5.22	$ 4.50	$ 3.98
Earnings Per Share, Diluted, Two Class Method [Abstract]
Net income applicable to common stockholders	$ 19,877	$ 17,568	$ 15,764
Total weighted-average basic shares outstanding	3,809.4	3,900.4	3,956.3
Add: Employee stock options, SARs and warrants	12.8	19.9	20.6
Total weighted-average diluted shares outstanding	3,822.2	3,920.3	3,976.9
Net income per share	$ 5.20	$ 4.48	$ 3.96
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	148	133	233