Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 1,082	$ 1,093
Weighted-average shares outstanding	465,703,240	468,903,086
Share-based compensation plans	3,770,351	3,828,604
Weighted-average shares outstanding and assumed conversions	469,473,591	472,731,690
Basic earnings per share (US$ per share)	$ 2.32	$ 2.33
Diluted earnings per share (US$ per share)	$ 2.30	$ 2.31
Potential anti-dilutive share conversions	2,116,188	969,654