Condensed Consolidated Statements 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, 2017		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)	(408,667)				(408,667)
Other comprehensive income (loss)	2,312			2,312
Repurchase of common stock - repurchase program (in shares)		(3,028,118)
Repurchase of common stock - repurchase program	(74,787)	$ (30)	(74,757)
Issuance of shares from employee equity plans (in shares)		3,035,071
Issuance of shares from employee equity plans	22,735	$ 31	22,704
Share-based compensation expense	38,896		38,896
Ending balance (in shares) at Jul. 31, 2018		143,050,180
Ending balance at Jul. 31, 2018	$ 1,778,954	$ 1,431	6,797,857	(8,705)	(5,011,629)
Beginning balance (in shares) at Oct. 31, 2018	154,318,531	154,318,531
Beginning balance at Oct. 31, 2018	$ 1,929,334	$ 1,543	6,881,223	(5,780)	(4,947,652)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	173,103				173,103
Other comprehensive income (loss)	(17,984)			(17,984)
Repurchase of common stock - repurchase program (in shares)		(2,881,564)
Repurchase of common stock - repurchase program	(111,925)	$ (29)	(111,896)
Issuance of shares from employee equity plans (in shares)		2,717,534
Issuance of shares from employee equity plans	22,895	$ 27	22,868
Share-based compensation expense	44,446		44,446
Settlement of debt conversion liability (in shares)		1,585,140
Settlement of debt conversion liability	52,944	$ 16	52,928
Shares repurchased for tax withholdings on vesting of restricted stock units (in shares)		(626,629)
Shares repurchased for tax withholdings on vesting of stock unit awards	$ (23,234)	$ (6)	(23,228)
Ending balance (in shares) at Jul. 31, 2019	155,113,012	155,113,012
Ending balance at Jul. 31, 2019	$ 2,119,384	$ 1,551	$ 6,866,341	$ (23,764)	$ (4,724,744)