Stock-Based Compensation - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017
Summary of Stock Option Activity [Abstract]
Options Outstanding at July 31, 2014	2,879,801
Options Outstanding at July 31, 2014, Weighted Average Exercise Price	$ 27.40
Options, Grants in Period	364,046
Options, Grants in Period, Weighted Average Exercise Price	$ 36.85	$ 35.13
Options, Exercised in Period	(397,402)
Options, Exercised in Period, Weighted Average Exercise Price	$ 31.01
Options, Forfeitures and Expirations in Period	(62,125)
Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 32.25
Options Outstanding at January 31, 2015	2,784,320
Options Outstanding at January 31, 2015, Weighted Average Exercise Price	$ 28.01
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 26.61	28.67
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 3 months 18 days
Options Outstanding, Aggregate Intrinsic Value	$ 28,850
Options Outstanding, Exercisable, Weighted Average Remaining Contractual Term	5 years 3 months 18 days
Options Outstanding, Exercisable, Aggregate Intrinsic Value	$ 23,097
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	$ 35.12
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	56,290
Summary of Service-Based Restricted Stock Unit and Restricted Share Activity [Abstract]
Service-Based RSUs and Restricted Shares Outstanding	58,206
Service-Based RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 33.12	$ 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	114,496
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 32.57
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	86,032
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	$ 25.61
Service-Based RSUs and Restricted Shares Outstanding	517,108
Service-Based RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 36.68
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(137,237)
Service-Based RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 24.73
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(23,423)
Service-Based RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 26.92
Service-Based RSUs and Restricted Shares Outstanding	442,480
Service-Based RSUs and Restricted Shares Outstanding, Weighted Average Grant Date Fair Value	$ 27.97