Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net income (loss)	$ 1,833	$ 1,194	$ 6,398	$ 1,115
Weighted-average shares outstanding	435,318,088	451,794,046	443,595,026	451,683,093
Share-based compensation plans	3,123,550	1,471,434	3,032,989	1,894,699
Weighted-average shares outstanding and assumed conversions	438,441,638	453,265,480	446,628,015	453,577,792
Basic earnings (loss) per share (US$ per share)	$ 4.21	$ 2.64	$ 14.42	$ 2.47
Diluted earnings (loss) per share (US$ per share)	$ 4.18	$ 2.63	$ 14.33	$ 2.46
Potential anti-dilutive share conversions	1,758,853	7,053,316	1,439,882	6,767,727