Stock Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 35.13
Shares authorized	3,275,315		3,275,315
Shares reserved for future issuance	4,046,476		4,046,476
Share-based compensation expense	$ 1,684	$ 2,051	$ 7,581	$ 7,445
Share-based compensation expense (net of tax)	1,263	$ 1,272	5,685	$ 4,616
Unrecognized compensation cost related to share-based compensation, pre tax	$ 12,273		$ 12,273
Weighted average period remaining			1 year 292 days
Options Outstanding, Exercisable	1,950,754	1,882,244	1,950,754	1,882,244
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 26.63	$ 28.37	$ 26.63	$ 28.37
Proceeds from stock options exercised	$ 63	$ 4,015	$ 10,011	$ 18,674
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	15	1,514	910	2,967
Intrinsic value of stock options exercised	2,983	7,809
Fair value of stock options vested	3,006	$ 2,901
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value			5	$ 4
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	$ 20		$ 20
Service Based Restricted Shares and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 36.79