Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 1,040	$ 1,082
Weighted-average shares outstanding	458,805,185	465,703,240
Share-based compensation plans	2,731,755	3,770,351
Weighted-average shares outstanding and assumed conversions	461,536,940	469,473,591
Basic earnings per share (US$ per share)	$ 2.27	$ 2.32
Diluted earnings per share (US$ per share)	$ 2.25	$ 2.30
Potential anti-dilutive share conversions	4,343,204	2,116,188