Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Cash flows from operating activities:
Net income	$ 15,432	$ 20,408	$ 22,754
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	57,562	58,286	58,109
Remeasurement (gain)/loss on foreign currency	5	152	(2)
Provision for losses on accounts receivable	591	860	445
Gain on sale of rental and lease equipment	(13,622)	(14,195)	(13,189)
Stock compensation expense	1,292	1,356	1,330
Excess tax benefit for share-based compensation	(358)	(183)	(251)
Deferred income taxes	(4,160)	(7,928)	(4,631)
Change in operating assets and liabilities:
Accounts receivable	(503)	(2,366)	1,322
Other assets	(7,532)	(6,568)	(931)
Accounts payable	1,195	260	(467)
Accrued expenses	4,586	(1,125)	4,068
Deferred revenue	(1,869)	229	373
Net cash provided by operating activities	52,619	49,186	68,930
Cash flows from investing activities:
Proceeds from sales of rental and lease equipment	34,261	35,224	31,119
Payments for purchase of rental and lease equipment	(70,954)	(58,678)	(64,088)
Payments for purchase of other property	(986)	(384)	(1,105)
Net cash used in investing activities	(37,679)	(23,838)	(34,074)
Cash flows from financing activities:
Borrowings under bank lines of credit	45,702	56,018	63,500
Payments under bank lines of credit	(43,315)	(66,018)	(53,500)
Minimum tax withholdings on share-based compensation	(462)	(11)	(36)
Excess tax benefit for share-based compensation	358	183	251
Payment of dividends	(19,656)	(19,657)	(43,765)
Net cash used in financing activities	(17,373)	(29,485)	(33,550)
Effect of exchange rate changes on cash	551	(319)	(194)
Net increase (decrease) in cash and cash equivalents	(1,882)	(4,456)	1,112
Cash and cash equivalents at beginning of year	5,946	10,402	9,290
Cash and cash equivalents at end of year	4,064	5,946	10,402
Supplemental Cash Flow Information [Abstract]
Interest paid, during the period	31	106	180
Income taxes paid, during the period	8,063	23,778	15,579
Dividends accrued during the period, not yet paid	155	211	340
Rental equipment acquisitions, not yet paid	4,430	4,479	4,965
Used equipment sales in accounts receivable and other assets, not yet collected	7,426	9,050	11,419
Transfers from other assets to rental and lease equipment	$ 14,338	$ 4,535	$ 2,937