Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Earnings Per Share, Basic, Two Class Method [Abstract]
Net income	$ 6,496	$ 4,960	$ 13,025	$ 9,884
Less: Preferred stock dividends	204	158	386	315
Net income applicable to common equity	6,292	4,802	12,639	9,569
Less: Dividends and undistributed earnings allocated to participating securities	191	168	407	359
Net income applicable to common stockholders	6,101	4,634	12,232	9,210
Total weighted-average basic shares outstanding	3,782.4	3,808.9	3,800.3	3,813.9
Net income per share (Basic)	$ 1.61	$ 1.22	$ 3.22	$ 2.41
Earnings Per Share, Diluted, Two Class Method [Abstract]
Net income applicable to common stockholders	$ 6,101	$ 4,634	$ 12,232	$ 9,210
Total weighted-average basic shares outstanding	3,782.4	3,808.9	3,800.3	3,813.9
Add: Employee stock options, SARs and warrants	31.9	11.6	30.3	13.1
Total weighted-average diluted shares outstanding	3,814.3	3,820.5	3,830.6	3,827.0
Net income per share (Diluted)	$ 1.60	$ 1.21	$ 3.19	$ 2.41
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Aggregate antidilutive number of shares issuable	8	159	11	164