Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 1,294	$ 1,305	$ 2,376	$ 2,398
Weighted-average shares outstanding	465,276,597	467,981,077	465,488,724	468,244,458
Share-based compensation plans	3,103,727	3,872,860	3,489,013	3,900,678
Weighted-average shares outstanding and assumed conversions	468,380,324	471,853,937	468,977,737	472,145,136
Basic earnings per share (US$ per share)	$ 2.78	$ 2.79	$ 5.10	$ 5.12
Diluted earnings per share (US$ per share)	$ 2.76	$ 2.77	$ 5.07	$ 5.08
Potential anti-dilutive share conversions	3,814,491	2,066,578	3,305,735	1,467,556