EARNINGS PER SHARE - Reconciliation from Basic Earnings Per Share to Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2024	Nov. 30, 2023	Nov. 30, 2024	Nov. 30, 2023
Earnings Per Share [Abstract]
Net income available to common stockholders	$ 1,163	$ 1,578	$ 2,214	$ 3,028
Determination of shares:
Weighted average common shares outstanding (in shares)	1,486.8	1,520.8	1,492.3	1,524.6
Assumed conversion of dilutive stock options and awards (in shares)	3.2	11.3	3.6	13.1
DILUTED WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (in shares)	1,490.0	1,532.1	1,495.9	1,537.7
Earnings per common share:
Basic (in dollars per share)	$ 0.78	$ 1.04	$ 1.48	$ 1.99
Diluted (in dollars per share)	$ 0.78	$ 1.03	$ 1.48	$ 1.97