Net loss per share (Details) - shares shares in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2015 |
Jun. 30, 2014 |
Jun. 30, 2015 |
Jun. 30, 2014 |
|
| Antidilutive securities excluded from the computation of diluted net loss per share | ||||
| Antidilutive securities excluded from computation of earnings per share (in shares) | 20,561 | 17,816 | 20,482 | 17,748 |
| Employee Stock Option | ||||
| Antidilutive securities excluded from the computation of diluted net loss per share | ||||
| Antidilutive securities excluded from computation of earnings per share (in shares) | 20,138 | 17,417 | 20,138 | 17,417 |
| Warrant to purchase common stock | ||||
| Antidilutive securities excluded from the computation of diluted net loss per share | ||||
| Antidilutive securities excluded from computation of earnings per share (in shares) | 200 | 200 | 200 | 200 |
| Employee Stock | ||||
| Antidilutive securities excluded from the computation of diluted net loss per share | ||||
| Antidilutive securities excluded from computation of earnings per share (in shares) | 223 | 199 | 144 | 131 |