INCOME TAXES - Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018
Provision for Income Taxes [Abstract]
Federal	$ 1,616	$ 979	$ 8,320
State	19	300	264
Foreign	1,144	1,097	1,100
Total current provision	2,779	2,376	9,684
Federal	(983)	483	(827)
State	50	(28)	(26)
Foreign	82	(1,646)	6
Total deferred benefit	(851)	(1,191)	(847)
Total provision for income taxes	$ 1,928	$ 1,185	$ 8,837
Effective income tax rate	16.00%	9.70%	71.10%