5. FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Aug. 31, 2020	May 31, 2020
Assets
Investment securities	$ 80	$ 80
Level 1
Assets
Investment securities	80	80
Level 2
Assets
Investment securities	0	0
Level 3
Assets
Investment securities	0	0
Money Market Funds
Assets
Investment securities	80	80
Money Market Funds | Level 1
Assets
Investment securities	80	80
Money Market Funds | Level 2
Assets
Investment securities	0	0
Money Market Funds | Level 3
Assets
Investment securities	$ 0	$ 0