Goodwill and Intangible Assets - Estimated Future Amortization Expense (Details) - USD ($) $ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Estimated future amortization expense | ||
| 2018 (remaining nine months) | $ 1,172 | |
| 2019 | 1,130 | |
| 2020 | 1,015 | |
| 2021 | 384 | |
| Carrying Value | $ 3,701 | $ 4,092 |