Convertible Senior Notes - Summary of Net Carrying Amount of Liability Component of 2025 and 2026 Convertible Notes (Details) - Convertible Debt - USD ($)	Sep. 30, 2020	Mar. 31, 2020
Convertible senior notes due 2026
Debt Instrument [Line Items]
Principal	$ 650,000,000
Unamortized discount	(137,991,000)
Unamortized issuance cost	(7,627,000)
Net carrying amount	504,382,000
Convertible senior notes due 2025
Debt Instrument [Line Items]
Principal	1,000,000,000	$ 1,000,000,000.0
Unamortized discount	(174,624,000)
Unamortized issuance cost	(9,856,000)
Net carrying amount	$ 815,520,000

Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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