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, 2019	Jan. 31, 2018
Summary of Stock Option Activity [Abstract]
Outstanding at July 31, 2018	2,504,633
Options Outstanding at July 31, 2018, Weighted Average Exercise Price	$ 28.23
New grants	276,238
Options, Grants in Period, Weighted Average Exercise Price	$ 43.96	$ 36.85
Exercised	(799,529)
Options, Exercised in Period, Weighted Average Exercise Price	$ 27.32
Forfeited or expired	(24,809)
Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 37.37
Outstanding at January 31, 2019	1,956,533
Options Outstanding at January 31, 2019, Weighted Average Exercise Price	$ 30.71
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 26.87	26.61
Options Outstanding, Weighted Average Remaining Contractual Term	6 years 8 months 12 days
Options Outstanding, Aggregate Intrinsic Value	$ 26,750
Options Outstanding, Exercisable, Weighted Average Remaining Contractual Term	5 years 8 months 12 days
Options Outstanding, Exercisable, Aggregate Intrinsic Value	$ 24,141
Performance-Based RSUs
Summary of Service and Performance-Based RSU Activity [Abstract]
Outstanding at July 31, 2018	108,097
Service and Performance-Based RSUs Outstanding, Weighted Average Grant Date Fair Value	$ 32.57
New grants	50,313
Service and Performance-Based RSUs, Grants in Period, Weighted Average Grant Date Fair Value	$ 50.70	33.12
Vested	0
Service and Performance-Based RSUs, Vested in Period, Weighted Average Grant Date Fair Value	$ 0.00
Forfeited	0
Service and Performance-Based RSUs, Forfeitures, Weighted Average Grant Date Fair Value	$ 0.00
Outstanding at January 31, 2019	158,410
Service and Performance-Based RSUs Outstanding, Weighted Average Grant Date Fair Value	$ 38.33
Service-Based RSUs
Summary of Service and Performance-Based RSU Activity [Abstract]
Outstanding at July 31, 2018	342,856
Service and Performance-Based RSUs Outstanding, Weighted Average Grant Date Fair Value	$ 29.05
New grants	78,254
Service and Performance-Based RSUs, Grants in Period, Weighted Average Grant Date Fair Value	$ 44.00	$ 36.68
Vested	(118,921)
Service and Performance-Based RSUs, Vested in Period, Weighted Average Grant Date Fair Value	$ 28.12
Forfeited	(24,228)
Service and Performance-Based RSUs, Forfeitures, Weighted Average Grant Date Fair Value	$ 30.53
Outstanding at January 31, 2019	277,961
Service and Performance-Based RSUs Outstanding, Weighted Average Grant Date Fair Value	$ 33.52