Stockholder's Investments - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($)	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
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	$ 19,100
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 6,512	$ 2,797
Options Outstanding, Beginning Balance, Price Lower Range	$ 19.96
Options Outstanding, Beginning Balance, Price Upper Range	38.31
Options Granted, Price Lower Range	32.83
Options Granted, Price Upper Range	38.83
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	$ 38.31
Options, Outstanding [Roll Forward]
Shares Outstanding, Beginning Balance	3,708,706
Options Granted	378,939
Options Exercised	(874,128)
Options Cancelled	(333,716)
Shares Outstanding, Ending Balance	2,879,801	3,708,706
Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Options Outstanding, Beginning Balance, Weighted Average Exercise Price	$ 27.34
Options Granted, Weighted Average Exercise Price	35.14	$ 20.02	$ 22.76
Options Exercised, Weighted Average Exercise Price	27.81
Options Cancelled, Weighted Average Exercise Price	34.29
Options Outstanding, Ending Balance, Weighted Average Exercise Price	$ 27.40	27.34
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	2,879,801
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	5 years 10 months 24 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 27.83
Exercise Price Range, Number of Exercisable Options	1,859,959
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	4 years 6 months
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 28.20
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		$ 20.07
$20.95 - $26.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	1,091,151
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	7 years 8 months 12 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 21.28
Exercise Price Range, Number of Exercisable Options	435,311
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	7 years 3 months 18 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 20.89
$27.00 - $32.99 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	1,205,146
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	$ 29.14
Exercise Price Range, Number of Exercisable Options	1,201,652
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	$ 29.14
$33.00 - $38.31 [Member]
Options Outstanding, Range of Exercise Prices [Abstract]
Exercise Price Range, Number of Outstanding Options	583,504
Exercise Price Range, Options Outstanding, Weighted Average Remaining Contractual Term	6 years 1 month 6 days
Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 37.37
Exercise Price Range, Number of Exercisable Options	222,996
Exercise Price Range, Exercisable Options, Weighted Average Remaining Contractual Term	1 year 2 months 12 days
Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 37.37
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	678,381
Restricted Shares and RSUs, Grants in Period	96,137
Restricted Shares and RSUs, Vested in Period	(187,532)
Restricted Shares and RSUs, Forfeited in Period	(69,878)
Restricted Shares and RSUs, Nonvested, Number	517,108	678,381
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 23.57
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	35.15
Restricted Shares and RSUs, Vested in Period, Weighted Average Grant Date Fair Value	23.56
Restricted Shares and RSUs, Forfeitures, Weighted Average Grant Date Fair Value	24.47
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 25.61	$ 23.57
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	0
Restricted Shares and RSUs, Grants in Period	58,206
Restricted Shares and RSUs, Vested in Period	0
Restricted Shares and RSUs, Forfeited in Period	0
Restricted Shares and RSUs, Nonvested, Number	58,206	0
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 0.00
Restricted Shares and RSUs, Grants in Period, Weighted Average Grant Date Fair Value	32.03
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	0.00
Restricted Shares and RSUs, Nonvested, Weighted Average Grant Date Fair Value	$ 32.03	$ 0.00