INCOME TAXES - Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2017
Provision for Income Taxes [Abstract]
Federal	$ 979	$ 8,320	$ 936
State	300	264	257
Foreign	1,097	1,100	1,475
Total current provision	2,376	9,684	2,668
Federal	483	(827)	(158)
State	(28)	(26)	(29)
Foreign	(1,646)	6	(253)
Total deferred benefit	(1,191)	(847)	(440)
Total provision for income taxes	$ 1,185	$ 8,837	$ 2,228
Effective income tax rate	9.70%	71.10%	19.10%