Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 528	$ 785	$ 2,151	$ 2,298
Weighted-average shares outstanding	324,210,936	334,472,324	325,904,502	337,083,498
Share-based compensation plans	2,962,484	3,201,656	3,269,724	3,298,569
Weighted-average shares outstanding and assumed conversions	327,173,420	337,673,980	329,174,226	340,382,067
Basic earnings per share (US$ per share)	$ 1.63	$ 2.35	$ 6.60	$ 6.82
Diluted earnings per share (US$ per share)	$ 1.62	$ 2.32	$ 6.53	$ 6.75
Potential anti-dilutive share conversions	1,907,815	1,227,575	1,503,830	1,410,340