Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill and Other Intangible Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Goodwill [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			$ 3,109
Additions			0
Balance as of February 29, 2016	$ 3,109		3,109
Customer Relationships [Roll Forward]
Amortization	(29)	$ (30)	(88)	$ (100)
Balance as of February 29, 2016	245
Goodwill and Other Intangible Assets [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			3,853
Additions			0
Amortization	(29)	$ (30)	(88)	$ (100)
Balance as of February 29, 2016	3,765		3,765
Customer relationships
Customer Relationships [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			333
Additions			0
Amortization			(88)
Balance as of February 29, 2016	245		333
Goodwill and Other Intangible Assets [Roll Forward]
Amortization			(88)
Trade name
Trade Name [Roll Forward]
Balance as of June 1, 2015 (net of amortization)			411
Additions			0
Balance as of February 29, 2016	$ 411		$ 411