Earnings per Share (details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings per Share disclosure
Net income	$ 919	$ 864	$ 2,654	$ 2,685
Participating share-based awards - allocated income	(7)	(6)	(19)	(20)
Net income available to common shareholders -- basic	912	858	2,635	2,665
Net income available to common shareholders -- diluted	$ 912	$ 858	$ 2,635	$ 2,665
Weighted average shares outstanding, basic	335.1	368.9	342.9	374.1
Weighted average effects of dilutive securities, stock options and performance shares (in shares)	3.8	4.0	3.6	4.0
Weighted average shares outstanding, diluted	338.9	372.9	346.5	378.1
Net income per common share, basic	$ 2.72	$ 2.33	$ 7.68	$ 7.12
Net income per common share, diluted	$ 2.69	$ 2.30	$ 7.60	$ 7.05