Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Convertible preferred stock - savings plan
Convertible preferred stock - savings plan, balance, beginning of year		$ 68
Convertible preferred stock - savings plan, redemptions during period		(2)
Convertible preferred stock - savings plan, balance, end of period		66
Common stock
Common stock, balance, beginning of year	20,732	20,162
Common stock, employee share-based compensation	68	156
Common stock, compensation amortization under share-based plans and other changes	51	52
Common stock, balance, end of period	20,851	20,370
Retained earnings
Retained earnings, balance, beginning of year	19,579	18,847
Net income	806	839
Dividends	(162)	(156)
Retained earnings, other		8
Retained earnings, balance, end of period	20,223	19,538
Accumulated other comprehensive income, net of tax
Accumulated other comprehensive income, net of tax, balance, beginning of year	2,005	1,255
Other comprehensive income	34	17
Accumulated other comprehensive income, net of tax, balance, end of period	2,039	1,272
Treasury stock (at cost)
Treasury stock (at cost), balance, beginning of year	(17,839)	(14,857)
Treasury stock (at cost), treasury shares acquired - share repurchase authorization	(350)	(1,100)
Treasury stock (at cost), net shares acquired related to employee share-based compensation plans	(52)	(46)
Treasury stock (at cost), balance, end of period	(18,241)	(16,003)
Total common shareholders' equity	24,872	25,177
Total shareholders' equity	$ 24,872	$ 25,243
Common shares outstanding
Common shares outstanding, balance, beginning of year	392.8	434.6
Common shares outstanding, treasury shares acquired - share repurchase authorization	(6.0)	(18.9)
Common shares outstanding, net shares issued under employee share-based compensation plans	3.0	4.6
Common shares outstanding, balance, end of period	389.8	420.3