STOCK-BASED COMPENSATION (Details 3) - Warrant [Member]	9 Months Ended
	Feb. 28, 2017 $ / shares shares
Shares outstanding	5,078,153
Weighted-average remaining life	1 year 11 months 26 days
Weighted-average exercise price (in dollars per share) | $ / shares	$ 1.57
Number exercisable	5,078,153
$1.00 [Member]
Shares outstanding	283,000
Weighted-average remaining life	1 year 8 months 19 days
Weighted-average exercise price (in dollars per share) | $ / shares	$ 1.00
Number exercisable	283,000
$1.20 [Member]
Shares outstanding	2,956,822
Weighted-average remaining life	2 years 5 months 8 days
Weighted-average exercise price (in dollars per share) | $ / shares	$ 1.20
Number exercisable	2,956,822
$2.00 [Member]
Shares outstanding	1,838,331
Weighted-average remaining life	1 year 3 months 25 days
Weighted-average exercise price (in dollars per share) | $ / shares	$ 2.00
Number exercisable	1,838,331