Stock incentive plans - Compensation expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2019 |
Jun. 30, 2018 |
Jun. 30, 2019 |
Jun. 30, 2018 |
|
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 2,036 | $ 2,946 | $ 4,380 | $ 6,072 |
| Stock-based compensation expense capitalized | 235 | 206 | 465 | 392 |
| Network operations | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 348 | 516 | 854 | 1,053 |
| Development and technology | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 334 | 314 | 637 | 592 |
| Selling and marketing | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 548 | 393 | 1,077 | 866 |
| General and administrative | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 806 | $ 1,723 | $ 1,812 | $ 3,561 |