Stock Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value			$ 24
Shares authorized	4,630,354		4,630,354
Shares reserved for future issuance	2,368,731		2,368,731
Share-based compensation expense	$ 1,678,000	$ 1,085,000	$ 6,247,000	$ 3,556,000
Share-based compensation expense (net of tax)	1,040,000	$ 673,000	3,873,000	$ 2,205,000
Unrecognized compensation cost related to share-based compensation, pre tax	$ 17,206,000		$ 17,206,000
Weighted average period remaining			2 years 7 months 6 days
Options Outstanding, Exercisable	2,679,527	2,706,566	2,679,527	2,706,566
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 30.09	$ 30.84	$ 30.09	$ 30.84
Proceeds from stock options exercised	$ 610,000	$ 744,000	$ 663,000	$ 1,591,000
Tax benefit on stock options exercised	37,000	35,000	40,000	79,000
Intrinsic value of stock options exercised	105,000	202,000
Fair value of stock options vested	3,193,000	$ 3,909,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Nonvested	$ 19,218		19,218
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value			$ 1,471	$ 805
Service Based Restricted Shares and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value			$ 20.07