2. STOCK-BASED COMPENSATION (Details 3) - Outstanding Options Stock Option Transactions $ / shares in Units, $ in Thousands	3 Months Ended
	Aug. 31, 2017 USD ($) $ / shares shares
Options Outstanding, Beginning (in thousands) | shares	3,074
Options granted (in thousands) | shares	224
Options cancelled (in thousands) | shares	0
Options exercised (in thousand) | shares	(189)
Options Outstanding, Ending (in thousands) | shares	3,109
Weighted Average Exercise Price Outstanding, Beginning | $ / shares	$ 1.73
Weighted Average Exercise Price Granted | $ / shares	3.93
Weighted Average Exercise Price Cancelled | $ / shares	0.00
Weighted Average Exercise Price Exercised | $ / shares	1.23
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 1.92
Aggregate Intrinsic Value, beginning balance | $	$ 8,763
Aggregate Intrinsic Value, ending balance | $	$ 4,612
Options fully vested and expected to vest, ending (in thousands) | shares	3,072
Weighted Average Exercise Price for Options fully vested and expected to vest, ending | $ / shares	$ 1.92
Aggregate Intrinsic Value for Options fully vested and expected to vest, ending | $	$ 4,577