Common Stock Repurchases - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Jan. 31, 2017	Jan. 31, 2017	May 26, 2016	Jun. 02, 2014
Stockholders Equity Note [Line Items]
Repurchase of common stock, shares	0	0
2014 repurchase program | Maximum
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock				$ 30,000,000
Remaining amount authorized for repurchase of Company's common stock				$ 1,000,000
2016 Repurchase program | Maximum
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock			$ 15,000,000