Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income	$ (331)	$ 1,150	$ (79)	$ 2,190
Weighted-average shares outstanding	451,402,807	457,224,455	451,635,733	458,010,447
Share-based compensation plans	1,395,951	2,945,237	2,044,144	2,863,109
Weighted-average shares outstanding and assumed conversions	451,402,807	460,169,692	451,635,733	460,873,556
Basic earnings per share (US$ per share)	$ (0.73)	$ 2.52	$ (0.17)	$ 4.78
Diluted earnings per share (US$ per share)	$ (0.73)	$ 2.50	$ (0.17)	$ 4.75
Potential anti-dilutive share conversions	8,378,447	2,660,925	6,583,319	5,037,959