Segment Reporting and Related Disclosures - Revenues from External Customers and Long-Lived Assets, by Geographical Areas (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	May. 31, 2015
Revenues:
Total revenues	[1]	$ 39,498	$ 56,342	$ 136,151	$ 177,916
Net Long-Lived Assets:
Total net long-lived assets	[2]	220,152		220,152		$ 244,791
U.S.
Revenues:
Total revenues	[1]	30,528	47,922	110,451	149,320
Net Long-Lived Assets:
Total net long-lived assets	[2]	174,482		174,482		197,514
Other
Revenues:
Total revenues	[1],[3]	8,970	$ 8,420	25,700	$ 28,596
Net Long-Lived Assets:
Total net long-lived assets	[2],[3]	$ 45,670		$ 45,670		$ 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.