Summary of Significant Accounting Policies - Fair Value and Carrying Value (Details) $ in Thousands	Jun. 30, 2021 USD ($)
2023 Series D Convertible Notes | Fair Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 135
2023 Series D Convertible Notes | Net Carrying Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	297
Series D Preferred Stock | Fair Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	9,366
Series D Preferred Stock | Net Carrying Value
Summary of Significant Accounting Policies [Line Items]
Debt instrument, fair value disclosure	$ 15,374