Warrants - Narrative (Details) - Rockport Warrants - $ / shares |
Sep. 30, 2021 |
Dec. 31, 2020 |
Mar. 31, 2017 |
|---|---|---|---|
| Class of Stock [Line Items] | |||
| Exercise price of warrants (in dollars per share) | $ 3.80 | $ 3.80 | |
| Warrants outstanding (in shares) | 5,500 | 5,500 | |
| Common Class B | |||
| Class of Stock [Line Items] | |||
| Number of shares called by warrants (in shares) | 145,000 |