11. STOCKHOLDERS’ EQUITY, COMPREHENSIVE INCOME AND STOCK-BASED COMPENSATION (Details 5) $ / shares in Units, $ in Thousands	3 Months Ended
	Aug. 31, 2018 USD ($) $ / shares shares
$0.59-$0.97
Options Outstanding, Ending (in thousands) | shares	259
Weighted Average Remaining Contractual Life (Years) Options Outstanding	6 months 4 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ .67
Options exercisable shares, ending (in thousands) | shares	259
Weighted Average Remaining Contractual Life (Years) Options Exercisable	6 months 4 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ .67
$1.09-$1.36
Options Outstanding, Ending (in thousands) | shares	507
Weighted Average Remaining Contractual Life (Years) Options Outstanding	1 year 3 months 11 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 1.28
Options exercisable shares, ending (in thousands) | shares	506
Weighted Average Remaining Contractual Life (Years) Options Exercisable	1 year 3 months 11 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ 1.28
$1.68-$2.06
Options Outstanding, Ending (in thousands) | shares	466
Weighted Average Remaining Contractual Life (Years) Options Outstanding	4 years 14 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 1.74
Options exercisable shares, ending (in thousands) | shares	318
Weighted Average Remaining Contractual Life (Years) Options Exercisable	3 years 7 months 20 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ 1.77
$2.10-$2.81
Options Outstanding, Ending (in thousands) | shares	1,695
Weighted Average Remaining Contractual Life (Years) Options Outstanding	4 years 4 months 2 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 2.44
Options exercisable shares, ending (in thousands) | shares	1,130
Weighted Average Remaining Contractual Life (Years) Options Exercisable	3 years 3 months 4 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ 2.47
$3.46-$3.93
Options Outstanding, Ending (in thousands) | shares	262
Weighted Average Remaining Contractual Life (Years) Options Outstanding	5 years 10 months 28 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 3.86
Options exercisable shares, ending (in thousands) | shares	94
Weighted Average Remaining Contractual Life (Years) Options Exercisable	5 years 11 months 16 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ 3.76
$0.59-$3.93
Options Outstanding, Ending (in thousands) | shares	3,189
Weighted Average Remaining Contractual Life (Years) Options Outstanding	3 years 7 months 28 days
Weighted Average Exercise Price Outstanding, Ending | $ / shares	$ 2.12
Options exercisable shares, ending (in thousands) | shares	2,307
Weighted Average Remaining Contractual Life (Years) Options Exercisable	2 years 8 months 19 days
Weighted Average Exercise Price for Options exercisable, ending | $ / shares	$ 1.96
Aggregate Intrinsic Value for Options exercisable, ending | $	$ 1,541