Consolidated Statement of Changes in Shareholders' Equity (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Common stock
Common stock, balance, beginning of year	$ 21,161	$ 20,732
Common stock, employee share-based compensation	76	68
Common stock, compensation amortization under share-based plans and other changes	63	51
Common stock, balance, end of period	21,300	20,851
Retained earnings
Retained earnings, balance, beginning of year	21,352	19,579
Net income	896	806
Dividends	(176)	(162)
Retained earnings, balance, end of period	22,072	20,223
Accumulated other comprehensive income, net of tax
Accumulated other comprehensive income, net of tax, balance, beginning of year	2,236	2,005
Other comprehensive income (loss)	(310)	34
Accumulated other comprehensive income, net of tax, balance, end of period	1,926	2,039
Treasury stock (at cost)
Treasury stock (at cost), balance, beginning of year	(19,344)	(17,839)
Treasury stock (at cost), treasury stock acquired - share repurchase authorization	(300)	(350)
Treasury stock (at cost), net shares acquired related to employee share-based compensation plans	(58)	(52)
Treasury stock (at cost), balance, end of period	(19,702)	(18,241)
Total shareholders' equity	$ 25,596	$ 24,872
Common shares outstanding
Common shares outstanding, balance, beginning of year	377.4	392.8
Common shares outstanding, treasury stock acquired - share repurchase authorization	(3.7)	(6.0)
Common shares outstanding, net shares issued under employee share-based compensation plans	2.7	3.0
Common shares outstanding, balance, end of period	376.4	389.8