Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Aug. 24, 2011	Aug. 31, 2011	May 31, 2012	May 31, 2011	May 31, 2013	Aug. 31, 2012
Business Acquisition [Line Items]
Total cash consideration	$ 10,673
Preliminary purchase price allocation:
Accounts receivable	542					972
Rental and lease equipment	15,896		243,173		234,856
Deferred tax liability	(2,092)
Deferred revenue	(479)
Net assets acquired	13,867
Bargain purchase gain, net of deferred taxes of $2,092	$ (3,194)	$ (3,194)	$ (3,435)	$ (202)