Debt - Summary of Information about the Equity and Liability Components of Notes (Details) - USD ($)	Dec. 31, 2020	Feb. 10, 2020	Dec. 31, 2019	Apr. 15, 2019
Debt Instrument [Line Items]
Total notes payable	$ 105,844,000		$ 62,414,000
Convertible Debt
Debt Instrument [Line Items]
Contractual interest expense	4,026,000		2,550,000	$ 80,000,000.0
Unamortized discount (including unamortized debt issuance cost)	4,355,000		2,529,000
Total notes payable	8,381,000		5,079,000
Convertible Debt | Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Contractual interest expense	13,750,000		80,000,000
Unamortized discount (including unamortized debt issuance cost)	(2,619,000)		(18,955,000)
Total notes payable	11,131,000		$ 61,045,000
Convertible Debt | Convertible Senior Notes Due 2026
Debt Instrument [Line Items]
Contractual interest expense	120,000,000	$ 120,000,000.0
Unamortized discount (including unamortized debt issuance cost)	(25,986,000)
Total notes payable	$ 94,014,000