Stock-Based Compensation - Summary of Option Activity (Detail)	6 Months Ended
	Nov. 30, 2016 $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Outstanding	225,000
Number of Shares, Granted	25,000
Number of Shares, Outstanding	250,000
Vested and exercisable options	40,000
Weighted average exercise price per share of vested and exercisable options | $ / shares	$ 3.12
Non-vested options	210,000
Weighted average grant-date fair value per share of non-vested options | $ / shares	$ 2.67