Consolidated Statement of Changes In Shareholders' Equity (USD $) In Millions, except Share data in Thousands, unless otherwise specified	Total	PREFERRED STOCK	COMMON STOCK	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	TREASURY STOCK
Beginning balance at Dec. 31, 2013	$ 20,378	$ 491	$ 504	$ 9,776	$ 13,395	$ (95)	$ (3,693)
Beginning balance (shares) at Dec. 31, 2013			503,883				69,754
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	363				363
Other comprehensive income (loss)	283					283
Accretion of issuance costs	742	(742)
Cash dividends declared:
Common stock dividends	(112)				(112)
Preferred stock cash dividend	(6)				(6)
Common stock acquired	(420)						(420)
Common stock acquired (shares)							6,075
Common stock awards and options exercised, including related taxes	(46)			(39)			(85)
Common stock awards and options exercised, including related taxes (shares)			(2)				(2,403)
Other	(1)				(1)
Other (shares)							(14)
Ending balance at Mar. 31, 2014	21,273	1,233	504	9,737	13,639	188	(4,028)
Ending balance (shares) at Mar. 31, 2014			503,881				73,440
Beginning balance at Dec. 31, 2014	21,473	1,961	504	9,791	14,882	(507)	(5,158)
Beginning balance (shares) at Dec. 31, 2014			503,880				88,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	409				409
Other comprehensive income (loss)	(499)					(499)
Cash dividends declared:
Common stock dividends	(124)				(124)
Preferred stock cash dividend	(31)				(31)
Common stock acquired	(470)						(470)
Common stock acquired (shares)							6,277
Common stock awards and options exercised, including related taxes	(62)			(47)			(109)
Common stock awards and options exercised, including related taxes (shares)							(2,400)
Other	(1)				(1)
Other (shares)							(7)
Ending balance at Mar. 31, 2015	$ 20,819	$ 1,961	$ 504	$ 9,744	$ 15,135	$ (1,006)	$ (5,519)
Ending balance (shares) at Mar. 31, 2015			503,880				92,569