Stockholder's Investments - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Beginning Balance, Price Lower Range	$ 19.96
Options Outstanding, Beginning Balance, Price Upper Range	43.98
Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Price	54.05
Options Exercised, Price Lower Range	19.96
Options Exercised, Price Upper Range	43.98
Options Cancelled, Price Lower Range	22.66
Options Cancelled, Price Upper Range	54.05
Options Outstanding, Ending Balance, Price Lower Range	19.96	$ 19.96
Options Outstanding, Ending Balance, Price Upper Range	$ 54.05	$ 43.98
Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning Balance	1,594,716
Options Granted	247,297
Options Exercised	(556,143)
Options Cancelled	(12,488)
Shares Outstanding, Ending Balance	1,273,382	1,594,716
Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options Outstanding, Beginning Balance, Weighted Average Exercise Price	$ 31.63
Options Granted, Weighted Average Exercise Price	54.05	$ 43.96	$ 36.85
Options Exercised, Weighted Average Exercise Price	27.21
Options Cancelled, Weighted Average Exercise Price	39.59
Options Outstanding, Ending Balance, Weighted Average Exercise Price	$ 37.84	$ 31.63
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	1,273,382
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	$ 37.84
Exercise Price Range, Number of Exercisable Options	776,273
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	5 years 6 months
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 31.50
$19.96 - $26.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	265,600
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	4 years 1 month 6 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 22.07
Exercise Price Range, Number of Exercisable Options	265,600
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	4 years 1 month 6 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 22.07
$27.00 - $32.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	519,870
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	6 years 2 months 12 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 35.36
Exercise Price Range, Number of Exercisable Options	433,576
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	6 years
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 35.07
$33.00 - $43.98 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	487,912
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	8 years 8 months 12 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 49.06
Exercise Price Range, Number of Exercisable Options	77,097
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	8 years 2 months 12 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 43.96
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, Vested in Period, Fair Value	$ 9,776	$ 9,859
Restricted Shares and RSUs, Nonvested, Number of Shares [Roll Forward]
Restricted Shares and RSUs, Nonvested, Number	188,638
Restricted Shares and RSUs, Grants in Period	76,358
Restricted Shares and RSUs, Vested in Period	(107,187)
Restricted Shares and RSUs, Forfeited in Period	(2,849)
Restricted Shares and RSUs, Nonvested, Number	154,960	188,638
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 38.15
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	53.38	$ 44.20
Restricted Shares and RSUs, Vested in Period, Weighted Average Grant Date Fair Value	35.49
Restricted Shares and RSUs, Forfeitures, Weighted Average Grant Date Fair Value	43.73
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 47.39	$ 38.15
Performance 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, Aggregate Intrinsic Value, Nonvested	$ 14,013	$ 17,953
Restricted Shares and RSUs, Nonvested, Number of Shares [Roll Forward]
Restricted Shares and RSUs, Nonvested, Number	158,410
Restricted Shares and RSUs, Grants in Period	71,921
Restricted Shares and RSUs, Vested in Period	(87,928)
Restricted Shares and RSUs, Forfeited in Period	(16,343)
Restricted Shares and RSUs, Nonvested, Number	126,060	158,410
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 38.33
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	75.00	$ 50.70
Restricted Shares and RSUs, Vested in Period, Weighted Average Grant Date Fair Value	32.03
Restricted Shares and RSUs, Forfeitures, Weighted Average Grant Date Fair Value	52.16
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 50.61	$ 38.33