Share Repurchase Programs - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended				18 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2011 June 2010 Repurchase Program	Jun. 30, 2010 June 2010 Repurchase Program
Stock Repurchase Program [Line Items]
Repurchase of common stock					$ 10,000,000
Repurchased number of shares					0.7
Cost of repurchase	158,000	188,000	1,633,000		4,800,000
Special dividend declared				$ 40,000,000