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, 2013	$ 20,248	$ 491	$ 504	$ 9,776	$ 13,265	$ (95)	$ (3,693)
Beginning balance (shares) at Dec. 31, 2013			503,883				69,754
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	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 at Dec. 31, 2014	21,328	1,961	$ 504	9,791	14,737	(507)	$ (5,158)
Ending balance (shares) at Dec. 31, 2014			503,880				88,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	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 at Dec. 31, 2015	21,103	2,703	$ 504	9,746	16,049	(1,442)	$ (6,457)
Ending balance (shares) at Dec. 31, 2015			503,880				104,228
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	2,143				2,143
Other comprehensive income (loss)	(598)					(598)
Preferred stock issued	493	493
Cash dividends declared:
Common stock dividends	(559)				(559)
Preferred stock cash dividend	(173)				(173)
Common stock acquired	(1,365)						$ (1,365)
Common stock acquired (shares)							21,098
Common stock awards and options exercised, including related taxes	175			36			$ 139
Common stock awards and options exercised, including related taxes (shares)							(3,369)
Other	0				(1)		$ 1
Other (shares)							(16)
Ending balance at Dec. 31, 2016	$ 21,219	$ 3,196	$ 504	$ 9,782	$ 17,459	$ (2,040)	$ (7,682)
Ending balance (shares) at Dec. 31, 2016			503,880				121,941