FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Nov. 30, 2022	May 31, 2022
Money Market Funds [Member]
Investment securities	$ 11,308	$ 28,609
U.S. treasury securities [Member]
Investment securities	21,683
Assets [Member]
Investment securities	32,991	28,609
Level 1 | U.S. treasury securities [Member]
Investment securities	21,683
Level 1 | Money Market Funds [Member]
Investment securities	11,308	28,609
Level 1 | Assets [Member]
Investment securities	32,991	28,609
Level 2 | U.S. treasury securities [Member]
Investment securities	0
Level 2 | Money Market Funds [Member]
Investment securities	0	0
Level 2 | Assets [Member]
Investment securities	0	0
Level 3 | U.S. treasury securities [Member]
Investment securities	0
Level 3 | Money Market Funds [Member]
Investment securities	0	0
Level 3 | Assets [Member]
Investment securities	$ 0	$ 0