Consolidated Statement of Changes In Shareholders' Equity - USD ($) shares in Thousands, $ in Millions	Total	PREFERRED STOCK	COMMON STOCK	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	TREASURY STOCK
Beginning balance at Dec. 31, 2012	$ 20,825	$ 489	$ 504	$ 9,667	$ 11,707	$ 360	$ (1,902)
Beginning balance (shares) at Dec. 31, 2012			503,900				45,238
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,050				2,050
Other comprehensive income (loss)	(455)					(455)
Accretion of issuance costs	0	2			(2)
Cash dividends declared:
Common stock dividends	(463)				(463)
Preferred stock cash dividend					(26)
Common stock acquired	(2,040)						$ (2,040)
Common stock acquired (shares)							31,237
Common stock awards and options exercised, including related taxes	362			113			$ 249
Common stock awards and options exercised, including related taxes (shares)			(17)				(6,709)
Other	(5)			(4)	(1)
Other (shares)							(12)
Ending balance (shares) at Dec. 31, 2013			503,883				69,754
Ending balance at Dec. 31, 2013	20,248	491	$ 504	9,776	13,265	(95)	$ (3,693)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,022				2,022
Other comprehensive income (loss)	(412)					(412)
Preferred stock issued	1,470	1,470
Cash dividends declared:
Common stock dividends	(490)				(490)
Preferred stock cash dividend	(61)				(61)
Common stock acquired	(1,650)						$ (1,650)
Common stock acquired (shares)							23,749
Common stock awards and options exercised, including related taxes	202			17			$ 185
Common stock awards and options exercised, including related taxes (shares)			(3)				(4,805)
Other	(1)			(2)	1
Other (shares)							(13)
Ending balance (shares) at Dec. 31, 2014			503,880				88,685
Ending balance at Dec. 31, 2014	21,328	1,961	$ 504	9,791	14,737	(507)	$ (5,158)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,980				1,980
Other comprehensive income (loss)	(935)					(935)
Preferred stock issued	742	742
Cash dividends declared:
Common stock dividends	(536)				(536)
Preferred stock cash dividend	(130)				(130)
Common stock acquired	(1,520)						$ (1,520)
Common stock acquired (shares)							20,521
Common stock awards and options exercised, including related taxes	180			(41)			$ 221
Common stock awards and options exercised, including related taxes (shares)							(4,976)
Other	(6)			(4)	(2)
Other (shares)							(2)
Ending balance (shares) at Dec. 31, 2015			503,880				104,228
Ending balance at Dec. 31, 2015	$ 21,103	$ 2,703	$ 504	$ 9,746	$ 16,049	$ (1,442)	$ (6,457)