Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Basic earnings per share
Net income	$ 5,520	$ 5,914
Less: Preferred stock dividends	412	324
Net income applicable to common equity	5,108	5,590
Less: Dividends and undistributed earnings allocated to participating securities	117	138
Net income applicable to common stockholders	$ 4,991	$ 5,452
Total weighted-average basic shares outstanding (in shares)	3,669.9	3,725.3
Net income per share (in dollars per share)	$ 1.36	$ 1.46
Diluted earnings per share
Net income applicable to common stockholders	$ 4,991	$ 5,452
Total weighted-average basic shares outstanding (in shares)	3,669.9	3,725.3
Add: Employee stock options, SARs and warrants (in shares)	27.0	32.2
Total weighted-average diluted shares outstanding (in shares)	3,696.9	3,757.5
Net income per share (in dollars per share)	$ 1.35	$ 1.45
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)		1.0