SHAREHOLDERS' EQUITY (Details) - Stock Options Summary	12 Months Ended
	May 31, 2020 $ / shares shares
Range Of Exercise Price $0.82 - $1.04 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	$ 0.82
Range of Exercise Price, Maximum	$ 1.04
Options Outstanding, Number (in Shares) | shares	276,000
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 160 days
Options Outstanding, Weighted Average Exercise Price	$ 0.84
Options Exercisable, Number (in Shares) | shares	276,000
Options Exercisable, Weighted Average Exercise Price	$ 0.84
Range Of Exercise Price $1.20 - $2.81 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	1.20
Range of Exercise Price, Maximum	$ 2.81
Options Outstanding, Number (in Shares) | shares	1,072,500
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 208 days
Options Outstanding, Weighted Average Exercise Price	$ 2.17
Options Exercisable, Number (in Shares) | shares	506,000
Options Exercisable, Weighted Average Exercise Price	$ 1.71
Range Of Exercise Price $3.62 - $8.18 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	3.62
Range of Exercise Price, Maximum	$ 8.18
Options Outstanding, Number (in Shares) | shares	440,751
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 226 days
Options Outstanding, Weighted Average Exercise Price	$ 5.38
Options Exercisable, Number (in Shares) | shares	184,667
Options Exercisable, Weighted Average Exercise Price	$ 3.87