Segment Reporting and Related Disclosures - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Aug. 31, 2014 Customer Segment	Aug. 31, 2013 Customer	Aug. 31, 2014 T&M	May 31, 2014 T&M	Aug. 31, 2014 DP	May 31, 2014 DP
Revenue from External Customer [Line Items]
Number of operating segment	2
Equipment pool, based on acquisition cost			$ 424,600	$ 421,128	$ 39,055	$ 37,911
Number of major customer accounted for more than 10% of total revenues	0	0

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration