Stock-based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands  | 
3 Months Ended | |
|---|---|---|
Mar. 31, 2021  | 
Mar. 31, 2020  | 
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| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||
| Compensation expense | $ 356 | $ 587 | 
| Sales and marketing | ||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||
| Compensation expense | 99 | 138 | 
| Research and development | ||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||
| Compensation expense | 52 | 73 | 
| General and administrative | ||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||
| Compensation expense | $ 205 | $ 376 | 
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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- 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. 
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