Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Cash flows from operating activities:
Net income	$ 25,772	$ 23,756	$ 11,597
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	54,960	49,127	43,759
Put option loss		952	671
Realized gain on redemption of trading securities		(952)	(671)
Remeasurement loss on foreign currency	267	43	93
Provision for losses on accounts receivable	233	500	529
Realized gain on sale of investments available for sale			(841)
Gain on sale of rental and lease equipment	(10,954)	(12,083)	(10,768)
Gain on bargain purchase, net of taxes	(3,435)	(202)	(679)
Stock compensation expense	1,438	956	610
Excess tax benefit for share based compensation	(102)	(37)	(62)
Deferred income taxes	11,120	23,454	(2,802)
Change in operating assets and liabilities:
Accounts receivable	(5,594)	(4,819)	(7,545)
Other assets	(5,839)	(8,950)	(4,268)
Accounts payable	(120)	1,184	939
Accrued expenses	1,516	(3,974)	2,467
Deferred revenue	613	(204)	1,144
Net cash provided by operating activities	69,875	68,751	34,173
Cash flows from investing activities:
Proceeds from sale of rental and lease equipment	25,042	32,917	36,661
Cash paid for acquisition	(10,327)		(24,653)
Proceeds from acquisition purchase price adjustment		260
Payments for purchase of rental and lease equipment	(96,709)	(91,538)	(56,891)
Redemptions of investments, available-for-sale			28,737
Redemptions of investments, trading		14,275	7,325
Payments for purchase of other property	(900)	(1,563)	(682)
Net cash used in investing activities	(82,894)	(45,649)	(9,503)
Cash flows from financing activities:
Borrowing under bank line of credit	3,250
Payment under bank line of credit	(3,250)
Proceeds from issuance of common stock		197	454
Minimum tax withholdings on share based compensation	(47)
Excess tax benefit for share based compensation	102	37	62
Payments for repurchase of common stock			(395)
Payment of dividends	(19,378)	(14,449)	(14,360)
Net cash used in financing activities	(19,323)	(14,215)	(14,239)
Net (decrease) increase in cash and cash equivalents	(32,342)	8,887	10,431
Effect of exchange rate changes on cash	191	(352)	260
Cash and cash equivalents at beginning of year	41,441	32,906	22,215
Cash and cash equivalents at end of year	$ 9,290	$ 41,441	$ 32,906