Segment Reporting and Related Disclosures - Revenues from External Customers and Long-Lived Assets, by Geographical Areas (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2014		Feb. 28, 2013		Feb. 28, 2014		Feb. 28, 2013		May 31, 2013
Revenues:
Total revenues	$ 62,016	[1]	$ 64,672	[1]	$ 180,060	[1]	$ 188,365	[1]
Net Long-Lived Assets:
Total net long-lived assets	237,012	[2]			237,012	[2]			248,682	[2]
U.S.
Revenues:
Total revenues	52,638	[1]	56,069	[1]	151,775	[1]	161,611	[1]
Net Long-Lived Assets:
Total net long-lived assets	195,472	[2]			195,472	[2]			198,956	[2]
Other
Revenues:
Total revenues	9,378	[1],[3]	8,603	[1],[3]	28,285	[1],[3]	26,754	[1],[3]
Net Long-Lived Assets:
Total net long-lived assets	$ 41,540	[2],[3]			$ 41,540	[2],[3]			$ 49,726	[2],[3]

[1] Revenues by country are based on the location of shipping destination, and not whether the order originates in the United States parent or a foreign subsidiary.

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

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