Business Combination - Pro forma combined revenue and net loss (Details) - USD ($) $ / shares in Units, $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Business Combination | ||
| Pro forma revenue | $ 294,446 | $ 223,532 |
| Pro forma net loss | $ (37,267) | $ (27,959) |
| Pro forma net loss per share, basic and diluted | $ (0.76) | $ (0.60) |