Condensed Consolidated Statements of Changes in Stockholders' Equity (USD $) In Millions, except Share data	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance, Amount at Dec. 31, 2012	$ 40,499	$ 0	$ 6	$ 26,188	$ 16,853	$ 739	$ (3,287)
Balance, Shares at Dec. 31, 2012		875,000	631,806,585
Comprehensive income (loss)	1,722				3,300	(1,578)
Cash dividends-common stock $0.65 per share	(383)				(383)
Cash dividends-preferred stock 6% per annum	(39)				(39)
Purchases of treasury stock	(287)						(287)
Issuances of common stock and restricted stock, net of forfeitures (in shares)			2,594,420
Issuances of common stock and restricted stock, net of forfeitures	64		0	64
Exercise of stock options and tax benefits of exercises and restricted stock vesting (in shares)			1,420,008
Exercise of stock options and tax benefits of exercises and restricted stock vesting	73		0	73
Compensation expense for restricted stock awards and stock options	101			101
Balance, Amount at Sep. 30, 2013	$ 41,750	$ 0	$ 6	$ 26,426	$ 19,731	$ (839)	$ (3,574)
Balance, Shares at Sep. 30, 2013		875,000	635,821,013