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Stock-based Compensation - Restricted Stock and Restricted Stock Units Activity (Details) - Restricted stock
9 Months Ended
Sep. 30, 2017
$ / shares
shares
NUMBER OF SHARES  
Beginning balance (in shares) | shares 164,194
Granted (in shares) | shares 332,512
Vested (in shares) | shares (54,591)
Canceled (in shares) | shares (2,566)
Ending balance (in shares) | shares 439,549
WEIGHTED AVERAGE FAIR VALUE PER SHARE  
Beginning balance (in dollars per share) | $ / shares $ 19.87
Granted (in dollars per share) | $ / shares 47.61
Vested (in dollars per share) | $ / shares 20.47
Canceled (in dollars per share) | $ / shares 43.90
Ending balance (in dollars per share) | $ / shares $ 40.64