Summary of Significant Accounting Policies - Fair Value and Carrying Value (Details) $ in Thousands	Dec. 31, 2020 USD ($)
2023 Series C Convertible Notes | Fair Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 30,148,000
2023 Series C Convertible Notes | Net Carrying Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	31,922,000
2023 Series D Convertible Notes | Fair Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	1,459,000
2023 Series D Convertible Notes | Net Carrying Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 5,796