Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	PREFERRED STOCK	COMMON STOCK	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	TREASURY STOCK
Beginning balance at Dec. 31, 2011	$ 19,398	$ 500	$ 504	$ 9,557	$ 10,176	$ (659)	$ (680)
Beginning balance (shares) at Dec. 31, 2011			503,966,000				16,542,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	427				427
Other comprehensive income	360					360
Cash dividends declared:
Common stock	(118)				(118)
Preferred stock	(7)				(7)
Common stock awards and options exercised, including related taxes (shares)			(25,000)				(2,290,000)
Common stock awards and options exercised, including related taxes	99			(11)			110
Other (shares)							(3,000)
Ending balance at Mar. 31, 2012	20,159	500	504	9,546	10,478	(299)	(570)
Ending balance (shares) at Mar. 31, 2012			503,941,000				14,249,000
Beginning balance at Dec. 31, 2012	20,869	489	504	9,667	11,751	360	(1,902)
Beginning balance (shares) at Dec. 31, 2012			503,900,000				45,238,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	464				464
Other comprehensive income	(109)					(109)
Cash dividends declared:
Common stock	(118)				(118)
Preferred stock	(7)				(7)
Common stock acquired (shares)	6,500,000						6,548,000
Common stock acquired	(360)						(360)
Common stock awards and options exercised, including related taxes (shares)			(4,000)				(3,475,000)
Common stock awards and options exercised, including related taxes	130			2			128
Other (shares)							(7,000)
Ending balance at Mar. 31, 2013	$ 20,869	$ 489	$ 504	$ 9,669	$ 12,090	$ 251	$ (2,134)
Ending balance (shares) at Mar. 31, 2013			503,896,000				48,304,000