Common Stock Repurchases - Additional Information (Detail) - USD ($)	3 Months Ended	29 Months Ended
	Oct. 31, 2016	Oct. 31, 2016	May 26, 2016	Jun. 02, 2014
2014 repurchase program
Stockholders Equity Note [Line Items]
Repurchase of common stock (in shares)		367,193
Repurchase of common stock		$ 29,000,000
Average purchase price of common stock		$ 78.93
Repurchase of common stock, shares	0
2014 repurchase program | Maximum
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock				$ 30,000,000
2016 Repurchase program | Maximum
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock			$ 15,000,000