Commitments and Contingencies - Operating Lease (Details) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2018
USD ($)
lease
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
|
|
| Commitments and Contingencies | |||
| Number of leases | lease | 3 | ||
| Rent expense | $ 2,400 | $ 1,000 | $ 400 |
| Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] | |||
| 2019 | 956 | ||
| 2020 | 713 | ||
| 2021 | 547 | ||
| Total | $ 2,216 | ||