Condensed Consolidated Statement of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Oct. 31, 2016		139,767,627
Beginning balance at Oct. 31, 2016	$ 766,341	$ 1,398	$ 6,715,478	$ (24,329)	$ (5,926,206)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	41,887				41,887
Other comprehensive income	3,143			3,143
Issuance of shares from employee equity plans (in shares)		2,000,821
Issuance of shares from employee equity plans	10,345	$ 20	10,325
Share-based compensation expense	24,830		24,830
Ending balance (in shares) at Apr. 30, 2017		141,768,448
Ending balance at Apr. 30, 2017	846,546	$ 1,418	6,750,633	(21,186)	(5,884,319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of adoption of new accounting standard	$ 62,123		832		61,291
Beginning balance (in shares) at Oct. 31, 2017	143,043,227	143,043,227
Beginning balance at Oct. 31, 2017	$ 2,136,342	$ 1,430	6,810,182	(11,017)	(4,664,253)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(459,507)				(459,507)
Other comprehensive income	$ 5,945			5,945
Repurchase of common stock (in shares)	(1,627,233)	(1,627,233)
Repurchase of common stock	$ (39,147)	$ (16)	(39,131)
Issuance of shares from employee equity plans (in shares)		2,011,982
Issuance of shares from employee equity plans	11,804	$ 20	11,784
Share-based compensation expense	$ 26,559		26,559
Ending balance (in shares) at Apr. 30, 2018	143,427,976	143,427,976
Ending balance at Apr. 30, 2018	$ 1,744,119	$ 1,434	$ 6,810,226	$ (5,072)	$ (5,062,469)