Stock Options and Warrants (Detail) (USD $)	6 Months Ended
	Nov. 30, 2012	May 31, 2012
Stock option and warrant activity
Options and warrants outstanding, Number of Shares	10,327,664
Granted, Number of Shares	9,145,676
Exercised, Number of Shares	(755,000)
Forfeited/expired/cancelled, Number of Shares	(750,000)
Options and warrants outstanding, Number of Shares	17,968,340	10,327,664
Outstanding exercisable, Number of Shares	16,376,596
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	$ 1.69	$ 1.60
Outstanding exercisable, Weighted Average Exercise Price	$ 1.65
Options and warrants outstanding, Weighted Average Remaining Contractual Life	2 years 2 months 1 day	3 years 2 months 12 days
Outstanding exercisable, Weighted Average Remaining Contractual Life	2 years 1 month 13 days
Options and warrants outstanding, Aggregate Intrinsic Value	$ 2,308,279
Options and warrants outstanding, Aggregate Intrinsic Value	3,092,853	2,308,279
Outstanding exercisable, Aggregate Intrinsic Value	$ 3,088,165