Stock Options and Warrants (Detail) (USD $)	9 Months Ended
	Feb. 28, 2013	May 31, 2012
Stock option and warrant activity
Options and warrants outstanding, Number of Shares	10,327,664
Granted, Number of Shares	9,615,633
Exercised, Number of Shares	(755,000)
Forfeited /expired/ cancelled, Number of Shares	(1,150,000)
Options and warrants outstanding, Number of Shares	18,038,297	10,327,664
Outstanding exercisable, Number of Shares	16,833,232
Options and warrants outstanding, Weighted Average Exercise Price	$ 1.60
Granted, Weighted Average Exercise Price	$ 1.70
Exercised, Weighted Average Exercise Price	$ 0.25
Forfeited /expired/ cancelled, Weighted Average Exercise Price	$ 2.00
Options and warrants outstanding, Weighted Average Exercise Price	$ 1.68	$ 1.60
Outstanding exercisable, Weighted Average Exercise Price	$ 1.67
Options and warrants outstanding, Weighted Average Remaining Contractual Life	2 years 7 days	3 years 2 months 12 days
Outstanding exercisable, Weighted Average Remaining Contractual Life	1 year 10 months 21 days
Options and warrants outstanding, Aggregate Intrinsic Value	$ 2,308,279
Options and warrants outstanding, Aggregate Intrinsic Value	1,793,958	2,308,279
Outstanding exercisable, Aggregate Intrinsic Value	$ 1,793,958