Segment Reporting and Related Disclosures - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Nov. 30, 2013 Customer Segment	Nov. 30, 2012 Customer	Nov. 30, 2013 T&M	May 31, 2013 T&M	Nov. 30, 2013 DP	May 31, 2013 DP
Revenue from External Customer [Line Items]
Number of operating segment	2
Minimum percentage of revenue accounted for major customer	10.00%
Equipment pool, based on acquisition cost			$ 432,488	$ 423,306	$ 36,832	$ 35,947
Number of major customer accounted for more than 10% of total revenues	0	0