Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended								6 Months Ended	12 Months Ended
		May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	Nov. 30, 2014	May 31, 2016	May 31, 2015	May 31, 2014
Schedule Of Quarterly Financial Information [Line Items]
Total revenues		$ 39,182	$ 39,498	$ 43,310	$ 53,343	$ 60,413	$ 56,342	$ 59,703	$ 61,871	$ 238,329	$ 175,333	$ 238,329	$ 241,137
Gross Profit	[1]	16,220	15,172	17,881	18,964	20,580	18,356	20,825	22,480	82,241	68,237
Income Before Taxes		(1,197)	1,492	3,541	3,951	5,646	3,746	7,696	7,562	24,650	7,787	24,650	32,526
Net income		$ (885)	$ 1,009	$ 2,190	$ 2,470	$ 3,441	$ 2,425	$ 4,795	$ 4,771	$ 15,432	$ 4,784	$ 15,432	$ 20,408
Basic, in dollars per share		$ (0.04)	$ 0.04	$ 0.09	$ 0.10	$ 0.14	$ 0.10	$ 0.20	$ 0.20	$ 0.63	$ 0.20	$ 0.63	$ 0.84
Diluted, in dollars per share		$ (0.04)	$ 0.04	$ 0.09	$ 0.10	$ 0.14	$ 0.10	$ 0.20	$ 0.20	$ 0.63	$ 0.20	$ 0.63	$ 0.84

[1] Gross profit is calculated as total revenues less depreciation of rental and lease equipment, costs of rentals and leases and costs of sales of equipment and other revenues.