Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 3,533	$ 4,454	$ 3,962
Weighted-average shares outstanding	451,602,820	455,910,463	463,629,203
Share-based compensation plans	1,838,692	3,004,200	3,173,145
Adjusted weighted-average shares outstanding and assumed conversions	453,441,512	458,914,663	466,802,348
Basic earnings per share	$ 7.82	$ 9.77	$ 8.55
Diluted earnings per share	$ 7.79	$ 9.71	$ 8.49
Potential anti-dilutive share conversions	6,811,966	2,410,337	3,543,188