SHAREHOLDERS' EQUITY (Details) - Stock Options Summary	12 Months Ended
	May 31, 2021 $ / 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	216,000
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 9 months
Options Outstanding, Weighted Average Exercise Price	$ 0.82
Options Exercisable, Number (in Shares) | shares	216,000
Options Exercisable, Weighted Average Exercise Price	$ 0.82
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	1,024,500
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 164 days
Options Outstanding, Weighted Average Exercise Price	$ 2.17
Options Exercisable, Number (in Shares) | shares	795,250
Options Exercisable, Weighted Average Exercise Price	$ 2.02
Range Of Exercise Price $3.62 - $8.70 [Member]
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	3.62
Range of Exercise Price, Maximum	$ 8.70
Options Outstanding, Number (in Shares) | shares	840,866
Options Outstanding, Weighted Average Remaining Contractual Life	8 years
Options Outstanding, Weighted Average Exercise Price	$ 6.03
Options Exercisable, Number (in Shares) | shares	276,875
Options Exercisable, Weighted Average Exercise Price	$ 4.54