Net loss per share attributable to common stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Numerator: | |||||||||||
| Net loss attributable to common stockholders, basic and diluted | $ (22,292) | $ (19,521) | $ (3,968) | ||||||||
| Denominator: | |||||||||||
| Weighted average common stock, basic and diluted (in shares) | 36,849 | 35,753 | 35,578 | ||||||||
| Net loss per share attributable to common stockholders: | |||||||||||
| Basic and diluted (in dollars per share) | $ (0.10) | $ (0.13) | $ (0.16) | $ (0.22) | $ (0.18) | $ (0.11) | $ (0.10) | $ (0.15) | $ (0.60) | $ (0.55) | $ (0.11) |