Net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Numerator: | ||
| Net loss attributable to common stockholders | $ (53,281) | $ (32,068) |
| Denominator: | ||
| Weighted-average common shares outstanding—basic and diluted | 20,199 | 5,196 |
| Net loss per share attributable to common stockholders—basic and diluted | $ (2.64) | $ (6.17) |