Stock incentive plans - Compensation expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Jun. 30, 2016 |
|
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 4,288 | $ 3,079 | $ 7,332 | $ 6,684 |
| Stock-based compensation expense capitalized | 173 | 189 | 367 | 371 |
| Network operations | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 562 | 531 | 1,108 | 1,177 |
| Development and technology | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 280 | 251 | 550 | 563 |
| Selling and marketing | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 639 | 458 | 1,065 | 1,007 |
| General and administrative | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 2,807 | $ 1,839 | $ 4,609 | $ 3,937 |