Notes Payable Related Party - Summary of Notes Payable Related Party (Details) - USD ($) $ in Thousands |
Sep. 30, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|---|---|
| Notes Payable Related Party [Abstract] | ||||
| Notes payable due to related parties, with varying interest rates between 8% to 12% annual, with varying maturity dates | $ 12,000 | $ 12,011 | $ 12,952 | $ 14,215 |
| Less debt discount | (49) | (141) | ||
| Less current portion | $ (12,000) | $ (12,011) | (924) | (1,427) |
| Non-current portion | $ 11,979 | $ 12,647 |