Stockholder's Investments - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($)	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
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, Aggregate Intrinsic Value, Nonvested	$ 17,249
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 8,237	$ 6,512
Options Outstanding, Beginning Balance, Price Lower Range	$ 19.96
Options Outstanding, Beginning Balance, Price Upper Range	38.83
Options Granted, Price Lower Range	36.85
Options Granted, Price Upper Range	36.85
Options Exercised, Price Lower Range	19.96
Options Exercised, Price Upper Range	38.31
Options Cancelled, Price Lower Range	19.96
Options Cancelled, Price Upper Range	38.31
Options Outstanding, Ending Balance, Price Lower Range	19.96	$ 19.96
Options Outstanding, Ending Balance, Price Upper Range	$ 38.83	$ 38.83
Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning Balance	2,879,801
Options Granted	364,046
Options Exercised	(622,916)
Options Cancelled	(116,298)
Shares Outstanding, Ending Balance	2,504,633	2,879,801
Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options Outstanding, Beginning Balance, Weighted Average Exercise Price	$ 27.40
Options Granted, Weighted Average Exercise Price	36.85	$ 35.14	$ 20.02
Options Exercised, Weighted Average Exercise Price	28.84
Options Cancelled, Weighted Average Exercise Price	31.42
Options Outstanding, Ending Balance, Weighted Average Exercise Price	$ 28.23	27.40
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	2,504,633
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	5 years 9 months 18 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 28.23
Exercise Price Range, Number of Exercisable Options	1,722,229
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	4 years 8 months 12 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 26.82
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value		$ 35.15
$20.95 - $26.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	846,353
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	6 years 8 months 12 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 20.84
Exercise Price Range, Number of Exercisable Options	611,735
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	6 years 6 months
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 21.16
$27.00 - $32.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	978,233
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	3 years 3 months 18 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 29.24
Exercise Price Range, Number of Exercisable Options	977,506
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	3 years 3 months 18 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 29.24
$33.00 - $38.31 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	680,047
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	8 years 4 months 24 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 35.97
Exercise Price Range, Number of Exercisable Options	132,988
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	7 years 2 months 12 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 35.13
Service Based Restricted Shares and Restricted Stock Units [Member]
Restricted Shares and RSUs, Nonvested, Number of Shares [Roll Forward]
Restricted Shares and RSUs, Nonvested, Number	517,108
Restricted Shares and RSUs, Grants in Period	94,457
Restricted Shares and RSUs, Vested in Period	(219,389)
Restricted Shares and RSUs, Forfeited in Period	(49,320)
Restricted Shares and RSUs, Nonvested, Number	342,856	517,108
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 25.61
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	36.80
Restricted Shares and RSUs, Vested in Period, Weighted Average Grant Date Fair Value	24.76
Restricted Shares and RSUs, Forfeitures, Weighted Average Grant Date Fair Value	26.94
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 29.05	$ 25.61
Performance Based Restricted Shares and Restricted Stock Units [Member]
Restricted Shares and RSUs, Nonvested, Number of Shares [Roll Forward]
Restricted Shares and RSUs, Nonvested, Number	58,206
Restricted Shares and RSUs, Grants in Period	56,290
Restricted Shares and RSUs, Vested in Period	0
Restricted Shares and RSUs, Forfeited in Period	(6,399)
Restricted Shares and RSUs, Nonvested, Number	108,097	58,206
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 32.03
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	33.12
Restricted Shares and RSUs, Vested in Period, Weighted Average Grant Date Fair Value	0.00
Restricted Shares and RSUs, Forfeitures, Weighted Average Grant Date Fair Value	32.57
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 32.57	$ 32.03