Stockholders' Equity and Stock-based Compensation (Details 2) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended			3 Months Ended
	Oct. 31, 2014		Jul. 31, 2014		Oct. 31, 2014	Oct. 31, 2014 Restricted Stock Units (RSUs)	Oct. 31, 2013 Restricted Stock Units (RSUs)
Number of RSUs Outstanding
Balance at beginning of period						3,384,221
Granted						1,096,112
Released						(519,154)
Canceled						(129,085)
Balance at end of period						3,832,094
Weighted Average Grant Date Fair Value
Balance at beginning of period						$ 30.70
Granted						$ 45.27	$ 43.74
Released						$ 21.84
Canceled						$ 32.70
Balance at end of period						$ 36.00
Number of Stock Options Outstanding
Balance at beginning of period	2,400,253
Granted	103,643
Exercised	(173,842)
Canceled	(40,803)
Balance at end of period	2,289,251		2,400,253
Vested and expected to vest as of October 31, 2014					2,261,137
Exercisable as of October 31, 2014	1,887,279
Weighted Average Exercise Price
Balance at beginning of period	$ 11.24
Granted	$ 45.27
Exercised	$ 8.32
Canceled	$ 24.18
Balance at end of period	$ 12.77		$ 11.24
Vested and expected to vest as of October 31, 2014					$ 12.40
Exercisable as of October 31, 2014	$ 6.78
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Life	5 years 3 months 18 days		5 years 6 months
Vested and expected to vest as of October 31, 2014	5 years 3 months 18 days
Exercisable as of October 31, 2014	5 years 3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Aggregate Intrinsic Value [Abstract]
Balance at beginning of period	$ 71,640	[1]
Balance at end of period	85,102	[1]	71,640	[1]
Vested and expected to vest as of October 31, 2014	84,889	[1]
Exercisable as of October 31, 2014	$ 81,469	[1]
Share Price	$ 49.94		$ 40.50

[1] Aggregate intrinsic value represents the difference between the Company's closing stock prices of $49.94 and $40.50 on October 31, 2014 and July 31, 2014, respectively, and the exercise price of outstanding, in-the-money options.