11. STOCKHOLDERS’ EQUITY, COMPREHENSIVE INCOME AND STOCK-BASED COMPENSATION (Details 4) - Outstanding Options Stock Option Transactions $ / shares in Units, $ in Thousands	3 Months Ended
	Aug. 31, 2018 USD ($) $ / shares shares
Options Outstanding, Beginning (in thousands) | shares	2,859
Options granted (in thousands) | shares	441
Options cancelled (in thousands) | shares	(13)
Options exercised (in thousand) | shares	(98)
Options Outstanding, Ending (in thousands) | shares	3,189
Weighted Average Exercise Price Outstanding, Beginning | $ / shares	$ 2.04
Weighted Average Exercise Price Granted | $ / shares	2.40
Weighted Average Exercise Price Cancelled | $ / shares	1.64
Weighted Average Exercise Price Exercised | $ / shares	1.12
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 2.12
Aggregate Intrinsic Value, beginning balance | $	$ 1,987
Aggregate Intrinsic Value, ending balance | $	$ 1,757
Options fully vested and expected to vest, ending (in thousands) | shares	3,156
Weighted Average Exercise Price for Options fully vested and expected to vest, ending | $ / shares	$ 2.12
Aggregate Intrinsic Value for Options fully vested and expected to vest, ending | $	$ 1,746