CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Nov. 30, 2014	May 31, 2014
Allowance for doubtful accounts	$ 659	$ 555
Accumulated depreciation on rental and lease equipment	241,856	237,151
Accumulated depreciation and amortization for other property	19,329	18,983
Accumulated amortization of intangibles	$ 1,702	$ 1,632
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	24,008,683	24,007,709
Common stock, shares outstanding	24,008,683	24,007,709