Earnings Per Share (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net income	$ 916	$ 640	$ 2,760	$ 1,941
Weighted-average shares outstanding	340,888,648	340,207,037	340,905,322	339,523,388
Share-based compensation plans	2,929,089	2,665,676	3,146,728	2,831,798
Adjusted weighted-average shares outstanding and assumed conversions	343,817,737	342,872,713	344,052,050	342,355,186
Basic earnings per share (US$ per share)	$ 2.68	$ 1.88	$ 8.09	$ 5.71
Diluted earnings per share (US$ per share)	$ 2.66	$ 1.86	$ 8.02	$ 5.67
Potential anti-dilutive share conversions	1,215,884	1,449,610	1,429,514	1,193,839