Stock-Based Compensation - Summary of Activity under Company's Share-Based Compensation Plans (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Summary of Stock Option Activity [Abstract]
Options Outstanding at July 31, 2014	4,204,260
Options Outstanding at July 31, 2014, Weighted Average Exercise Price	$ 30.82
Options, Grants in Period	622,983
Options, Grants in Period, Weighted Average Exercise Price	$ 22.73	$ 30.98
Options, Exercised in Period	(66,033)
Options, Exercised in Period, Weighted Average Exercise Price	$ 23.83
Options, Forfeitures and Expirations in Period	(1,118,335)
Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price	$ 30.97
Options Outstanding at April 30, 2015	3,642,875
Options Outstanding at April 30, 2015, Weighted Average Exercise Price	$ 29.52
Options Outstanding, Exercisable	2,706,566	3,131,418
Options Outstanding, Exercisable, Weighted Average Exercise Price	$ 30.84	$ 30.97
Options Outstanding, Weighted Average Remaining Contractual Term	5 years 7 months 6 days
Options Outstanding, Aggregate Intrinsic Value	$ 3,420,880
Options Outstanding, Exercisable, Weighted Average Remaining Contractual Term	4 years 4 months 24 days
Options Outstanding, Exercisable, Aggregate Intrinsic Value	$ 1,054,126
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	104,857
RSUs and Restricted Shares Outstanding at July 31, 2014, Weighted Average Grant Date Fair Value	$ 31.02
RSUs and Restricted Shares, Grants in Period	241,447
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 23.59
RSUs and Restricted Shares, Vested in Period	(34,247)
RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 30.79
RSUs and Restricted Shares, Forfeited in Period	(29,756)
RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 29.53
RSUs and Restricted Shares Outstanding at April 30, 2015	282,301
RSUs and Restricted Shares Outstanding at April 30, 2015, Weighted Average Grant Date Fair Value	$ 24.85
Performance 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	80,000
RSUs and Restricted Shares Outstanding at July 31, 2014, Weighted Average Grant Date Fair Value	$ 32.50
RSUs and Restricted Shares, Grants in Period	0
RSUs and Restricted Shares, Grants in Period, Weighted Average Grant Date Fair Value	$ 0.00
RSUs and Restricted Shares, Vested in Period	0
RSUs and Restricted Shares, Vested in Period, Weighted Average Grant Date Fair Value	$ 0.00
RSUs and Restricted Shares, Forfeited in Period	(80,000)
RSUs and Restricted Shares, Forfeitures, Weighted Average Grant Date Fair Value	$ 32.50
RSUs and Restricted Shares Outstanding at April 30, 2015	0
RSUs and Restricted Shares Outstanding at April 30, 2015, Weighted Average Grant Date Fair Value	$ 0.00