Summary of Significant Accounting Policies - Disaggregation of Revenue - Revenue by Region (Details) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Revenue: | ||
| Revenue | $ 48,434 | $ 35,945 |
| United States | ||
| Revenue: | ||
| Revenue | 40,493 | 31,730 |
| All other countries | ||
| Revenue: | ||
| Revenue | $ 7,941 | $ 4,215 |