CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Feb. 28, 2014	May 31, 2013
Allowance for doubtful accounts	$ 479	$ 457
Accumulated depreciation on rental and lease equipment	236,796	224,397
Accumulated depreciation and amortization for other property	19,538	18,873
Accumulated amortization of intangibles	$ 1,591	$ 1,468
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued
Common stock, par value
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	24,007,708	23,995,626
Common stock, shares outstanding	24,007,708	23,995,626