Stock-Based Compensation - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Summary of Stock Option Activity [Abstract]
Options Outstanding at July 31, 2014	3,714,039
Options Outstanding at July 31, 2014, Weighted Average Exercise Price	$ 27.34
Options, Grants in Period	378,939
Options, Grants in Period, Weighted Average Exercise Price	$ 35.14	$ 20.02
Options, Exercised in Period	(856,057)
Options, Exercised in Period, Weighted Average Exercise Price	$ 27.68
Options, Forfeitures and Expirations in Period	(304,823)
Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 35.06
Options Outstanding at January 31, 2015	2,932,098
Options Outstanding at January 31, 2015, Weighted Average Exercise Price	$ 27.44
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 28.37	$ 30.09
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 1 month 6 days
Options Outstanding, Aggregate Intrinsic Value	$ 34,919,577
Options Outstanding, Exercisable, Weighted Average Remaining Contractual Term	4 years 9 months 18 days
Options Outstanding, Exercisable, Aggregate Intrinsic Value	$ 20,664,011
Summary of Service-Based Restricted Stock Unit and Restricted Share Activity [Abstract]
Service-Based RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 20.07
Performance Based Restricted Shares and Restricted Stock Units [Member] [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	58,206
Summary of Service-Based Restricted Stock Unit and Restricted Share Activity [Abstract]
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 0.00
Service-Based RSUs and Restricted Shares Outstanding	0
Service-Based RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 32.03
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	0
Service-Based RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 0.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	0
Service-Based RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 0.00
Service-Based RSUs and Restricted Shares Outstanding	58,206
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 32.03
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	93,355
Summary of Service-Based Restricted Stock Unit and Restricted Share Activity [Abstract]
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 23.57
Service-Based RSUs and Restricted Shares Outstanding	678,381
Service-Based RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 35.13
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(118,000)
Service-Based RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 22.89
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(47,235)
Service-Based RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 24.35
Service-Based RSUs and Restricted Shares Outstanding	606,501
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 25.42