Segment Reporting and Related Disclosures - Additional Information (Detail) $ in Thousands	6 Months Ended
	Nov. 30, 2015 USD ($) Segment Customer	Nov. 30, 2014 Customer	May. 31, 2015 USD ($)
Revenue from External Customer [Line Items]
Number of operating segment | Segment	2
Number of major customer accounted for more than 10% of total revenues | Customer	0	0
DP
Revenue from External Customer [Line Items]
Equipment pool, based on acquisition cost	$ 37,241		$ 37,824
T&M
Revenue from External Customer [Line Items]
Equipment pool, based on acquisition cost	$ 417,562		$ 434,963