Net Loss per Share - Summary of Antidilutive Securities (Details) - Class A [Member] - shares
shares in Thousands |
12 Months Ended |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |
16,362
|
17,906
|
81,338
|
| Convertible Preferred Stock [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |
0
|
0
|
64,476
|
| Stock Options and Restricted Common Stock [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |
16,247
|
17,791
|
16,687
|
| Warrants [Member] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |
115
|
115
|
175
|