INCOME TAXES - Components of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Provision for Income Taxes [Abstract]
Federal	$ 8,329	$ 936	$ 1,301
State	264	257	271
Foreign	1,084	1,475	1,074
Total current provision	9,677	2,668	2,646
Federal	(614)	(201)	(123)
State	(13)	(36)	(21)
Foreign	16	(249)	39
Total deferred benefit	(611)	(486)	(105)
Total provision for income taxes	$ 9,066	$ 2,182	$ 2,541
Effective income tax rate	70.30%	18.90%	22.20%