11. CAPITAL STOCK (Details) - Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2015
Available Shares Stock Option Transactions
Available Shares, Beginning	1,847,000	845,000	1,145,000
Additional shares reserved	2,238,000	800,000	860,000
Options granted	(368,000)	(92,000)	(1,253,000)
RSUs granted	(157,000)	(35,000)
Options terminated	55,000	329,000	93,000
Plan shares expired	(1,446,000)
Available Shares, Ending	2,169,000	1,847,000	845,000
Outstanding Options Stock Option Transactions
Options Outstanding, Beginning	3,201,000	3,686,000	3,002,000
Options Granted	368,000	92,000	1,253,000
Options terminated	(55,000)	(329,000)	(93,000)
Options exercised	(440,000)	(248,000)	(476,000)
Number of Options Outstanding, Ending	3,074,000	3,201,000	3,686,000
Options exercisable and expected to be exercisable	3,030,000	3,137,000
Weighted Average Exercise Price Outstanding, Beginning	$ 1.66	$ 1.66	$ 1.31
Weighted Average Exercise Price Granted	1.83	2.12	2.38
Weighted Average Exercise Price Terminated	1.42	1.93	2.30
Weighted Average Exercise Price Exercised	1.35	1.34	1.33
Weighted Average Exercise Price Outstanding, Ending	1.73	$ 1.66	$ 1.66
Weighted Average Exercise Price Exercisable and expected to be exercisable	$ 1.72
Aggregate Intrinsic Value, beginning balance	$ 189	$ 2,946	$ 2,913
Aggregate Intrinsic Value, ending balance	8,763	$ 189	$ 2,946
Aggregate Intrinsic Value for Options exercisable and expected to be exercisable	$ 8,654