12. CAPITAL STOCK (Details) - Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Available Shares Stock Option Tranactions
Available Shares, Beginning	1,145,000	1,737,000	839,000
Additional shares reserved	860,000	0	1,223,000
Options granted	(1,253,000)	(908,000)	(670,000)
Options terminated	93,000	420,000	569,000
Plan shares expired	0	(104,000)	(224,000)
Available Shares, Ending	845,000	1,145,000	1,737,000
Outstanding Options Stock Option Transactions
Options Outstanding, Beginning	3,002,000	2,956,000	2,957,000
Options Granted	1,253,000	908,000	670,000
Options terminated	(93,000)	(420,000)	(569,000)
Options exercised	(476,000)	(442,000)	(102,000)
Number of Options Outstanding, Ending	3,686,000	3,002,000	2,956,000
Options exercisable and expected to be exercisable	3,612,000
Weighted Average Exercise Price Outstanding, Beginning	$ 1.31	$ 1.79	$ 2.40
Weighted Average Exercise Price Granted	2.38	1.64	1.13
Weighted Average Exercise Price Terminated	2.30	5.51	4.37
Weighted Average Exercise Price Exercised	1.33	1.17	0.67
Weighted Average Exercise Price Outstanding, Ending	1.66	$ 1.31	$ 1.79
Weighted Average Exercise Price Exercisable and expected to be exercisable	$ 1.66
Aggregate Intrinsic Value, beginning balance	$ 2,913	$ 964	$ 587
Aggregate Intrinsic Value, ending balance	2,946	$ 2,913	$ 964
Aggregate Intrinsic Value for Options exercisable and expected to be exercisable	$ 2,887