| Stock-based Compensation - Compensation Expense (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | |
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||||
| Compensation expense | $ 508 | $ 557 | $ 1,095 | $ 1,193 | 
| Sales and marketing | ||||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||||
| Compensation expense | 98 | 156 | 236 | 379 | 
| Research and development | ||||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||||
| Compensation expense | 40 | 73 | 113 | 118 | 
| General and administrative | ||||
| Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] | ||||
| Compensation expense | $ 370 | $ 328 | $ 746 | $ 696 | 
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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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