Consolidated Balance Sheets (Parenthetical) - $ / shares	Jul. 31, 2015	Jul. 31, 2014
Stockholders’ equity:
Preferred stock, par value (in dollars per share)	$ 0.1	$ 0.1
Preferred stock, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, shares Issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.1	$ 0.1
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	31,165,401	31,016,469
Treasury stock, shares (in shares)	15,033,317	14,857,582