Fair Value Measurements - Schedule of Carrying Amounts and Estimated Fair Values of Convertible Note (Details) - Senior Notes $ in Thousands	Oct. 31, 2020 USD ($)
Net Carrying Amount | Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Convertible senior notes	$ 35,614
Net Carrying Amount | Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Convertible senior notes	876,852
Net Carrying Amount | Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Convertible senior notes	856,489
Estimated Fair Value | Convertible Senior Notes Due 2023
Debt Instrument [Line Items]
Convertible senior notes	182,234
Estimated Fair Value | Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Convertible senior notes	1,393,052
Estimated Fair Value | Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Convertible senior notes	$ 1,316,750