Stock-Based Compensation - Restricted Stock Units (Details) - Restricted Stock Units
12 Months Ended
Dec. 31, 2016
USD ($)
$ / shares
shares
Restricted Stock Units  
Granted (in shares) | shares 163,784
Cancelled (in shares) | shares (4,138)
Unvested at end of year (in shares) | shares 159,646
Weighted-Average Grant Date Fair Value  
Granted (in dollars per share) | $ / shares $ 17.30
Cancelled (in dollars per share) | $ / shares 26.33
Unvested at the end of year (in dollars per share) | $ / shares $ 17.07
Unrecognized compensation cost | $ $ 2,234,847
Weighted-average period expected to be recognized 3 years 1 month 6 days