Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Nov. 30, 2011	Nov. 30, 2010
Cash flows from operating activities:
Net income	$ 14,524	$ 12,340
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	26,542	24,176
Put option loss		952
Realized gain on redemption of trading securities		(952)
Remeasurement loss (gain) on foreign currency	75	(3)
Provision for losses on accounts receivable	132	169
Gain on sale of rental and lease equipment	(4,948)	(5,064)
Gain on bargain purchase, net of deferred taxes	(3,382)	(202)
Stock compensation expense	710	436
Excess tax benefit from share based compensation	(50)	(25)
Deferred income taxes	5,200	6,995
Changes in operating assets and liabilities:
Accounts receivable	(3,958)	(2,789)
Other assets	205	(3,225)
Accounts payable	(1,556)	20
Accrued expenses	156	(4,809)
Deferred revenue	654	45
Net cash provided by operating activities	34,304	28,064
Cash flows from investing activities:
Proceeds from sale of rental and lease equipment	11,152	12,993
Cash paid for acquisition	(10,625)
Proceeds from acquisition purchase price adjustment		202
Payments for purchase of rental and lease equipment	(53,773)	(49,701)
Redemptions of investments, trading		14,275
Payments for purchase of other property	(475)	(535)
Net cash used in investing activities	(53,721)	(22,766)
Cash flows from financing activities:
Proceeds from issuance of common stock		197
Excess tax benefit from share based compensation	50	25
Payment of dividends	(9,653)	(7,237)
Net cash used in financing activities	(9,603)	(7,015)
Net decrease in cash and cash equivalents	(29,020)	(1,717)
Effect of exchange rate changes on cash	109	(122)
Cash and cash equivalents at beginning of period	41,441	32,906
Cash and cash equivalents at end of period	$ 12,530	$ 31,067