Earnings Per Share - Reconciliation from Basic Earnings Per Share to Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 847	$ 1,101	$ 3,329	$ 3,040
Determination of shares:
Weighted average common shares outstanding (in shares)	1,556.3	1,572.8	1,559.8	1,582.8
Assumed conversion of dilutive stock options and awards (in shares)	35.3	36.8	34.8	38.7
DILUTED WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (in shares)	1,591.6	1,609.6	1,594.6	1,621.5
Earnings per common share:
Basic (in dollars per share)	$ 0.54	$ 0.70	$ 2.13	$ 1.92
Diluted (in dollars per share)	$ 0.53	$ 0.68	$ 2.09	$ 1.87