Net Income (Loss) Per Share (Details) - shares
|
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
18,571,555
|
12,997,374
|
7,800,841
|
| Stock appreciation rights |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
2,422,716
|
2,072,130
|
1,400,824
|
| Options to purchase common stock |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
43,513
|
87,026
|
87,026
|
| Warrants to purchase common stock |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
0
|
0
|
17,916
|
| 2019 Convertible notes |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
7,895,675
|
10,838,218
|
6,295,075
|
| 2036 Convertible notes |
|
|
|
| Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |
|
|
|
| Anti-dilutive securities (in shares) |
8,209,651
|
0
|
0
|