Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014
Goodwill [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			$ 3,109
Additions			0
Balance as of November 30, 2015	$ 3,109		3,109
Customer Relationships [Roll Forward]
Amortization	(30)	$ (29)	(59)	$ (41)
Balance as of November 30, 2015	274
Goodwill and Other Intangible Assets [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			3,853
Additions			0
Amortization	(30)	$ (29)	(59)	$ (41)
Balance as of November 30, 2015	3,794		3,794
Customer relationships
Customer Relationships [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			333
Additions			0
Amortization			(59)
Balance as of November 30, 2015	274		333
Goodwill and Other Intangible Assets [Roll Forward]
Amortization			(59)
Trade name
Trade Name [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			411
Additions			0
Balance as of November 30, 2015	$ 411		$ 411