Stock-Based Compensation - Employee Stock Purchase Plan (Details) - USD ($) shares in Thousands, $ in Thousands |
1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended | ||||
|---|---|---|---|---|---|---|---|---|
Mar. 31, 2021 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||
| Stock-based compensation expense | $ 4,848 | $ 1,619 | $ 12,100 | $ 3,561 | $ 20,527 | $ 1,680 | $ 1,442 | |
| 2021 Employee Stock Purchase Plan | ||||||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||
| Common Stock, Capital Shares Reserved for Future Issuance | 3,000 | |||||||
| Share-based compensation arrangement by share-based payment award, annual increase in shares authorized as a percentage of outstanding common shares | 1.00% | |||||||
| Maximum | 2021 Employee Stock Purchase Plan | ||||||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||
| Stock-based compensation expense | $ 100 | $ 100 | ||||||
| X | ||||||||||
- Definition Annual increase in shares authorized as a percentage of outstanding shares of common stock on the last day of the immediately preceding fiscal year under the share based compensation plan. No definition available.
|
| X | ||||||||||
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Aggregate number of common shares reserved for future issuance. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|