Convertible Senior Notes - Schedule of Carrying Amount of the Liability and Equity (Details) - Convertible Senior Notes - USD ($) $ in Thousands	Oct. 31, 2020	Jun. 05, 2020
2023 Notes
Liability component:
Principal amount	$ 776,661	$ 776,700
Unamortized discount	(99,870)
Unamortized issuance costs	(3,897)
Net carrying amount	672,894
2023 Notes, Total prior to partial repurchase
Liability component:
Principal amount		1,265,000
Unamortized discount		(184,336)
Unamortized issuance costs		(7,194)
Net carrying amount		1,073,470
2023 Notes, Partial repurchase
Liability component:
Principal amount		488,339
Unamortized discount		(71,161)
Unamortized issuance costs		(2,777)
Net carrying amount		$ 414,401
2025 Notes
Liability component:
Principal amount	862,500
Unamortized discount	(175,741)
Unamortized issuance costs	(4,835)
Net carrying amount	681,924
2027 Notes
Liability component:
Principal amount	1,265,000
Unamortized discount	(331,022)
Unamortized issuance costs	(13,483)
Net carrying amount	$ 920,495