Share-Based Compensation - Restricted Stock Award Activity (Details) - $ / shares |
3 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
Dec. 31, 2012 |
|
| Shares | |||||
| Granted | 683,401 | ||||
| Restricted Stock Awards | |||||
| Shares | |||||
| Outstanding at beginning of period | 2,477,465 | 458,299 | 160,220 | ||
| Granted | 8,994,729 | 2,365,000 | 508,303 | ||
| Vested | (1,892,049) | (127,084) | (50,004) | ||
| Forfeited | (324,213) | (218,750) | (160,220) | ||
| Outstanding at end of period | 9,255,932 | 2,477,465 | 458,299 | 160,220 | |
| Weighted- Average Grant Date Fair Value | |||||
| Outstanding at beginning of period (in dollars per share) | $ 8.71 | $ 11.45 | $ 21.23 | ||
| Granted (in dollars per share) | 3.34 | 8.39 | 11.46 | ||
| Vested (in dollars per share) | 5.24 | 11.46 | 11.47 | ||
| Forfeited (in dollars per share) | 7.61 | 9.40 | 21.23 | ||
| Outstanding at end of period (in dollars per share) | $ 4.24 | $ 8.71 | $ 11.45 | $ 21.23 | |
| Weighted- Average Remaining Contractual Term (in years) | |||||
| Outstanding at end of period | 9 years 4 months 24 days | 9 years 3 months 18 days | 9 years 4 months 24 days | 9 years | |