INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2018	Aug. 31, 2017	May 31, 2018
Income Tax Examination [Line Items]
Effective income tax rate	10.80%	14.20%
Federal statutory income tax rate, percent	21.00%
Income tax benefit, adjustments to estimate of U.S. Tax Cuts and Jobs Act of 2017 one-time transition tax	$ 153
Deferred Tax Assets, Net [Abstract]
Net deferred tax assets	$ 1,400		$ 1,300
Domestic [Member]
Income Tax Examinations [Abstract]
Income tax examinations	Domestically, U.S. federal and state taxing authorities are currently examining income tax returns of Oracle and various acquired entities for years through fiscal 2017. Our U.S. federal income tax returns have been examined for all years prior to fiscal 2007, and we are no longer subject to audit for those periods. Our U.S. state income tax returns, with some exceptions, have been examined for all years prior to fiscal 2004, and we are no longer subject to audit for those periods.
Foreign [Member]
Income Tax Examinations [Abstract]
Income tax examinations	Internationally, tax authorities for numerous non-U.S. jurisdictions are also examining returns affecting our unrecognized tax benefits. With some exceptions, we are generally no longer subject to tax examinations in non-U.S. jurisdictions for years prior to fiscal 1997.