Stockholders' Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified			12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014 Common Stock	Sep. 15, 2011 Common Stock
Class of Stock [Line Items]
Stock repurchase program, authorized amount				$ 25
Share repurchase program, term			The Company determines the timing and amount of the transaction based on its evaluation of market conditions and other factors. The repurchase program may be suspended or discontinued at any time and has no expiration date.
Stock repurchased during period, shares			3,294,666
Stock repurchased during period, value			$ 18.7
Common stock reserved for possible issuance under stock based compensation plan and employee stock purchase plan	5,274,122	5,234,279