14. STOCK-BASED COMPENSATION (Details 3) - Outstanding Options Stock Option Transactions $ / shares in Units, $ in Thousands	3 Months Ended
	Aug. 31, 2020 USD ($) $ / shares shares
Options outstanding, beginning (in thousands) | shares	3,153
Options granted (in thousands) | shares	200
Options cancelled (in thousands) | shares	(188)
Options exercised (in thousand) | shares	(148)
Options outstanding, ending (in thousands) | shares	3,017
Options fully vested and expected to vest (in thousands) | shares	2,981
Weighted average exercise price outstanding, beginning | $ / shares	$ 2.17
Weighted average exercise price granted | $ / shares	1.86
Weighted average exercise price cancelled | $ / shares	2.18
Weighted average exercise price exercised | $ / shares	1.30
Weighted average exercise price outstanding, ending | $ / shares	2.19
Weighted average exercise price for options fully vested and expected to vest, ending | $ / shares	$ 2.19
Aggregate intrinsic value, beginning balance | $	$ 102
Aggregate intrinsic value, ending balance | $	148
Aggregate intrinsic value for options fully vested and expected to vest, ending | $	$ 145