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, 2014	$ 21,328	$ 1,961	$ 504	$ 9,791	$ 14,737	$ (507)	$ (5,158)
Beginning balance (shares) at Dec. 31, 2014			503,880				88,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	405				405
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 (shares) at Mar. 31, 2015			503,880				92,569
Ending balance at Mar. 31, 2015	20,670	1,961	$ 504	$ 9,744	14,986	(1,006)	$ (5,519)
Beginning balance at Dec. 31, 2015	21,103	2,703	$ 504	9,746	16,049	(1,442)	$ (6,457)
Beginning balance (shares) at Dec. 31, 2015			503,880				104,228
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	368				368
Other comprehensive income (loss)	478					478
Cash dividends declared:
Common stock dividends	(135)				(135)
Preferred stock cash dividend	(49)				(49)
Common stock acquired	(325)						$ (325)
Common stock acquired (shares)							5,615
Common stock awards and options exercised, including related taxes	57			(7)			$ 64
Common stock awards and options exercised, including related taxes (shares)							(1,542)
Other	(1)						$ (1)
Other (shares)							15
Ending balance (shares) at Mar. 31, 2016			503,880				108,316
Ending balance at Mar. 31, 2016	$ 21,496	$ 2,703	$ 504	$ 9,739	$ 16,233	$ (964)	$ (6,719)