Stock-Based Compensation - Summary of Activity under Company's Share-Based Compensation Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 7 months 6 days
Summary of Stock Option Activity [Abstract]
Options Outstanding at July 31, 2014	3,500,951
Options Outstanding at July 31, 2014, Weighted Average Exercise Price	$ 29.64
Options, Grants in Period	881,744
Options, Grants in Period, Weighted Average Exercise Price	$ 20.02	$ 22.73
Options, Exercised in Period	(28,782)
Options, Exercised in Period, Weighted Average Exercise Price	$ 23.04
Options, Forfeitures and Expirations in Period	(449,029)
Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 30.90
Options Outstanding at January 31, 2015	3,904,884
Options Outstanding at January 31, 2015, Weighted Average Exercise Price	$ 27.37
Options Outstanding, Exercisable	2,679,527	2,706,566
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 30.09	$ 30.84
Options Outstanding, Weighted Average Remaining Contractual Term	5 years 8 months 12 days
Options Outstanding, Aggregate Intrinsic Value	$ 7,963,025
Options Outstanding, Exercisable, Weighted Average Remaining Contractual Term	4 years 2 months 12 days
Options Outstanding, Exercisable, Aggregate Intrinsic Value	$ 1,483,578
Summary of Restricted Stock Unit and Restricted Share Activity [Abstract]
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 24
Service Based Restricted Shares and Restricted Stock Units [Member]
Summary of Restricted Stock Unit and Restricted Share Activity [Abstract]
RSUs and Restricted Shares Outstanding at July 31, 2014	677,454
RSUs and Restricted Shares Outstanding at July 31, 2014, Weighted Average Grant Date Fair Value	$ 24.72
RSUs and Restricted Shares, Grants in Period	173,394
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 20.07
RSUs and Restricted Shares, Vested in Period	(72,164)
RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 25.12
RSUs and Restricted Shares, Forfeited in Period	(53,214)
RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 23.77
RSUs and Restricted Shares Outstanding at January 31, 2015	725,470
RSUs and Restricted Shares Outstanding at January 31, 2015, Weighted Average Grant Date Fair Value	$ 23.64