Intangible Assets & Goodwill - Additional Information (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Goodwill and Intangible Assets Disclosure [Abstract] | ||||||
| Amortization expense | $ 3,300 | $ 500 | $ 7,847 | $ 1,700 | $ 2,993 | $ 1,753 |