Summary of Significant Accounting Policies - Fair Value and Carrying Value (Details) $ in Thousands	Mar. 31, 2021 USD ($)
2023 Series D Convertible Notes | Estimate of Fair Value Measurement
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 126
2023 Series D Convertible Notes | Reported Value Measurement
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	297
Series D Preferred Stock | Estimate of Fair Value Measurement
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	10,627
Series D Preferred Stock | Reported Value Measurement
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 15,374