Employee Benefit Plans - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Schedule of Employee Benefit Plans [Line Items]
Employer match and administrative fees for 401(k) plan	$ 316	$ 293	$ 294
Investments under the plan	$ 8,970	$ 8,715