Consolidated Statement of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Beginning Balance at May. 31, 2014	$ 536,835,000	$ 353,000	$ 508,354,000	$ 31,501,000	$ (1,269,000)	$ (2,104,000)
Beginning Balance,Treasury Shares at May. 31, 2014	(142,305)
Beginning Balance, Shares at May. 31, 2014		35,442,004
Net income (loss)	470,000			470,000
Exercise of stock options	206,000	1,000	205,000
Exercise of stock options, Shares		17,008
Purchase of common stock under ESPP	751,000	1,000	750,000
Purchase of common stock under ESPP, Shares		62,574
Issuance of performance shares	1,000	1,000
Issuance of performance shares, Shares		124,905
Stock based compensation	1,395,000		1,395,000
Other comprehensive income, net of tax	26,000				26,000
Ending Balance at Aug. 31, 2014	$ 539,684,000	$ 356,000	$ 510,704,000	$ 31,971,000	$ (1,243,000)	$ (2,104,000)
Ending Balance,Treasury Shares at Aug. 31, 2014	(142,305)					(142,305.000)
Ending Balance, Shares at Aug. 31, 2014		35,646,491