Stock incentive plans - Compensation expenses (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
|
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 3,006 | $ 2,256 | $ 9,690 | $ 6,190 |
| Stock-based compensation expense capitalized | 182 | 177 | 553 | 602 |
| Network operations | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 483 | 336 | 1,660 | 1,095 |
| Development and technology | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 267 | 319 | 830 | 546 |
| Selling and marketing | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | 424 | 600 | 1,431 | 1,769 |
| General and administrative | ||||
| Recognized stock-based compensation expense | ||||
| Total stock-based compensation | $ 1,832 | $ 1,001 | $ 5,769 | $ 2,780 |