Consolidated Condensed Balance Sheets (Parenthetical) - $ / shares	Apr. 30, 2016	Jul. 31, 2015	Apr. 30, 2015
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized	25,000,000	25,000,000	25,000,000
Preferred stock, shares issued	0	0	0
Preferred stock, shares outstanding	0	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000	100,000,000
Common stock, shares issued	41,595,420	41,462,941	41,309,969
Treasury stock, shares	5,434,977	4,949,111	4,949,111