Stockholder's Equity (Details 3) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended					12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Apr. 30, 2015	Oct. 31, 2014	Oct. 31, 2013	Jul. 31, 2016
Number Of Options [Roll Forward]
Exercise of stock options, net of repurchased shares (in shares)	(1,130,000)	(200,000)	(139,690)	(201,333)	(14,000)
Weighted Average Exercise Price [Roll Forward]
Exercises (in dollars per share)	$ 18.64	$ 12.02	$ 20.27	$ 19.59	$ 16.43
Stock Options
Number Of Options [Roll Forward]
Outstanding at July 31, 2015 (in shares)						21,011,000
Grants of options (in shares)						432,000
Exercise of stock options, net of repurchased shares (in shares)						(1,830,000)
Forfeitures or expirations (in shares)						(162,000)
Outstanding at July 31, 2016 (in shares)	19,451,000	21,011,000				19,451,000
Exercisable at July 31, 2016 (in shares)	14,640,000					14,640,000
Vested and expected to vest at July 31, 2016 (in shares)	19,121,000					19,121,000
Weighted Average Exercise Price [Roll Forward]
Outstanding at July 31, 2015 (in dollars per share)						$ 23.65
Grants of options (in dollars per share)						38.71
Exercises (in dollars per share)						19.19
Forfeitures or expirations (in dollars per share)						35.87
Outstanding at July 31, 2016 (in dollars per share)	$ 24.30	$ 23.65				24.30
Exercisable at July 31, 2016 (in dollars per share)	20.47					20.47
Vested and expected to vest at July 31, 2016 (in dollars per share)	$ 24.10					$ 24.10
Weighted-Average Remaining Contractual Term [Roll Forward]
Outstanding at July 31, 2015						5 years 9 months 11 days
Outstanding at July 31, 2016						4 years 11 months 16 days
Exercisable at July 31, 2016						3 years 10 months 28 days
Vested and expected to vest at July 31, 2016						4 years 10 months 24 days
Aggregate Intrinsic Value [Roll Forward]
Outstanding at July 31, 2015						$ 261,339
Outstanding at July 31, 2016	$ 508,401	$ 261,339				508,401
Exercisable at July 31, 2016	438,774					438,774
Vested and expected to vest at July 31, 2016	$ 503,601					$ 503,601