Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jul. 31, 2016	Jul. 31, 2015
Statement of Financial Position [Abstract]
Trade receivables, allowances	$ 616	$ 746
Inventories, reserves	$ 1,713	$ 1,915
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	41,614,432	41,462,941
Treasury stock, shares	5,434,977	4,949,111