CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - 3 months ended Mar. 31, 2017 - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2016	$ 47,514	$ 0	$ 7	$ 31,157	$ 29,766	$ (949)	$ (12,467)
Beginning balance (shares) at Dec. 31, 2016		4,475,000	653,736,607
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	825				810	15
Common Stock Dividends, Shares			24,812
Dividends, Common Stock	(195)		$ 0		(197)
Dividends, Share-based Compensation, Stock				2
Cash dividends - preferred series	(53)				(53)
Purchases of treasury stock	(218)						(218)
Issuances of common stock and restricted stock, shares, net of forfeitures			2,362,842
Issuances of common stock and restricted stock, value, net of forfeitures	41		$ 0	41
Exercise of stock options and warrants, tax effects of exercises and restricted stock vesting, shares			2,590,626
Exercise of stock options and warrants, tax effects of exercises and restricted stock vesting, value	65		$ 0	65
Compensation expense for restricted stock awards, restricted stock units and stock options	61			61
Ending balance at Mar. 31, 2017	$ 48,040	$ 0	$ 7	$ 31,326	$ 30,326	$ (934)	$ (12,685)
Ending balance (shares) at Mar. 31, 2017		4,475,000	658,714,887