Stock Based Compensation - Restricted Stock and Stock Options (Details) - USD ($)
$ / shares in Units, $ in Thousands |
3 Months Ended |
12 Months Ended |
|
Mar. 31, 2016 |
Mar. 31, 2015 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Mar. 31, 2016 |
| Changes in unvested restricted stock |
|
|
|
|
|
| Unvested restricted common stock, beginning of period (in shares) |
1,596,853
|
|
|
|
|
| Vested (in shares) |
(193,551)
|
|
|
|
|
| Unvested restricted common stock, end of period(in shares) |
1,403,302
|
|
1,596,853
|
|
|
| Weighted Average Grant Date Fair Value |
|
|
|
|
|
| Balance, beginning of period |
$ 0.0188
|
|
|
|
|
| Vested (in dollars per share) |
0.0162
|
|
|
|
|
| Balance, beginning of period |
$ 0.0192
|
|
$ 0.0188
|
|
|
| Compensation expense |
$ 4,210
|
$ 65
|
|
|
|
| Changes in unvested stock options |
|
|
|
|
|
| Options exercised prior to vesting (in shares) |
|
|
|
75,304
|
|
| Options exercised prior to vesting , exercise price per share |
|
|
|
$ 0.03
|
|
| Unvested stock options (in shares) |
|
|
39,338
|
|
34,992
|
| Outstanding, beginning of period (in shares) |
1,713,385
|
|
|
|
|
| Granted (in shares) |
695,312
|
|
|
|
|
| Exercised (in shares) |
(8,673)
|
|
|
|
|
| Outstanding, end of period (in shares) |
2,400,024
|
|
1,713,385
|
|
|
| Vested and expected to vest (in shares) |
|
|
|
|
2,360,999
|
| Exercisable (in shares) |
|
|
|
|
113,801
|
| Outstanding, beginning of period (in dollars per share) |
$ 6.31
|
|
|
|
|
| Granted (in dollars per share) |
18.68
|
|
|
|
|
| Exercised (in dollars per share) |
3.85
|
|
|
|
|
| Outstanding, end of period (in dollars per share) |
$ 9.90
|
|
$ 6.31
|
|
|
| Vested and expected to vest outstanding, weighted average exercise price (in dollars per share) |
|
|
|
|
$ 9.90
|
| Exercisable (in dollar per share) |
|
|
|
|
$ 4.88
|
| Remaining contractual life |
9 years 4 months 24 days
|
|
9 years 7 months 6 days
|
|
|
| Vested and expected to vest, remaining contractual life |
9 years 4 months 24 days
|
|
|
|
|
| Exercisable, remaining contractual life |
9 years 1 month 6 days
|
|
|
|
|
| Outstanding, beginning of Period aggregate intrinsic |
$ 15,580
|
|
|
|
|
| Outstanding, end of Period aggregate intrinsic |
$ 15,580
|
|
$ 15,580
|
|
$ 59,134
|
| Vesting and expected to vest, aggregate intrinsic value |
|
|
|
|
58,172
|
| Exercisable, aggregated intrinsic value |
|
|
|
|
3,376
|
| Employees and directors |
|
|
|
|
|
| Changes in unvested stock options |
|
|
|
|
|
| Weighted average fair value of options granted (per share) |
$ 13.03
|
$ 0.47
|
|
|
|
| Employees |
|
|
|
|
|
| Weighted Average Grant Date Fair Value |
|
|
|
|
|
| Compensation expense |
$ 900
|
$ 3,000
|
|
|
|
| Unrecognized stock-based compensation expense |
|
|
|
|
14,800
|
| Period for recognition |
3 years 4 months 24 days
|
|
|
|
|
| Restricted Stock | Employees |
|
|
|
|
|
| Weighted Average Grant Date Fair Value |
|
|
|
|
|
| Compensation expense |
$ 0
|
0
|
|
|
|
| Unrecognized stock-based compensation expense |
|
|
|
|
0
|
| Restricted Stock | Non-employees |
|
|
|
|
|
| Weighted Average Grant Date Fair Value |
|
|
|
|
|
| Compensation expense |
$ 2,400
|
$ 59,000
|
|
|
|
| Unrecognized stock-based compensation expense |
|
|
|
|
$ 16,600
|
| Period for recognition |
1 year 3 months 18 days
|
|
|
|
|