Common Stock Repurchases - Additional Information (Detail) - 2016 Repurchase program - USD ($)	3 Months Ended	9 Months Ended	23 Months Ended
	Apr. 30, 2018	Apr. 30, 2018	Apr. 30, 2018	May 26, 2016
Stockholders Equity Note [Line Items]
Amount authorized for repurchase of Company's common stock				$ 15,000,000
Repurchase of common stock (in shares)	0	13,489	61,197
Repurchase of common stock		$ 1,000,000	$ 4,400,000
Average purchase price of common stock		$ 70.52	$ 71.07