Segment Reporting and Related Disclosures - Revenues from External Customers and Long-Lived Assets, by Geographical Areas (Detail) - USD ($) $ in Thousands		3 Months Ended
		Aug. 31, 2015	Aug. 31, 2014	May. 31, 2015
Revenues:
Total revenues	[1]	$ 53,343	$ 61,871
Net Long-Lived Assets:
Total net long-lived assets	[2]	239,665		$ 244,791
U.S.
Revenues:
Total revenues	[1]	44,347	51,152
Net Long-Lived Assets:
Total net long-lived assets	[2]	191,166		197,514
Other
Revenues:
Total revenues	[1],[3]	8,996	$ 10,719
Net Long-Lived Assets:
Total net long-lived assets	[2],[3]	$ 48,499		$ 47,277

[1] Revenues by country are based on the shipping destination.

[2] Net long-lived assets include rental and lease equipment and other property, net of accumulated depreciation and amortization.

[3] Other consists of countries other than the U.S. Each foreign country individually accounts for less than 10% of the total consolidated revenues and net long-lived assets.