Stock Option Plan - Exercise Price Range (Details) - $ / shares
 11 Months Ended 12 Months Ended
Dec. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Information about stock options outstanding      
Options Outstanding, Number   2,350,582 784,136
Options Outstanding, Weighted Average Remaining Contractual Life   9 years 2 months 16 days 9 years 7 months 17 days
Weighted average exercise price of options outstanding (in dollars per share)   $ 11.88 $ 4.09
Options Vested, Number   397,486 9,637
Options Vested, Weighted Average Remaining Contractual Life   8 years 10 months 2 days 9 years 22 days
Weighted average exercise price of options vested (in dollars per share)   $ 8.02 $ 0.28
Weighted average grant date fair value of options granted (in dollars per share) $ 0.22 10.78 4.37
$0.28      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)   $ 0.28  
Options Outstanding, Number   419,682  
Options Outstanding, Weighted Average Remaining Contractual Life   8 years 5 months 16 days  
Weighted average exercise price of options outstanding (in dollars per share)   $ 0.28  
Options Vested, Number   159,732  
Options Vested, Weighted Average Remaining Contractual Life   8 years 5 months 9 days  
Weighted average exercise price of options vested (in dollars per share)   $ 0.28  
$4.65      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)   $ 4.65  
Options Outstanding, Number   144,500  
Options Outstanding, Weighted Average Remaining Contractual Life   8 years 9 months 22 days  
Weighted average exercise price of options outstanding (in dollars per share)   $ 4.65  
Options Vested, Number   42,449  
Options Vested, Weighted Average Remaining Contractual Life   8 years 9 months 22 days  
Weighted average exercise price of options vested (in dollars per share)   $ 4.65  
$6.75      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)   $ 6.75  
Options Outstanding, Number   5,000  
Options Outstanding, Weighted Average Remaining Contractual Life   8 years 10 months 13 days  
Weighted average exercise price of options outstanding (in dollars per share)   $ 6.75  
Options Vested, Number   1,438  
Options Vested, Weighted Average Remaining Contractual Life   8 years 10 months 13 days  
Weighted average exercise price of options vested (in dollars per share)   $ 6.75  
$13.34 - 16.37      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)   13.34  
Exercise Price, high end of range (in dollars per share)   $ 16.37  
Options Outstanding, Number   1,781,400  
Options Outstanding, Weighted Average Remaining Contractual Life   9 years 5 months 1 day  
Weighted average exercise price of options outstanding (in dollars per share)   $ 15.21  
Options Vested, Number   193,867  
Options Vested, Weighted Average Remaining Contractual Life   9 years 2 months 5 days  
Weighted average exercise price of options vested (in dollars per share)   $ 15.14  
$0.28 - 4.65      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)     0.28
Exercise Price, high end of range (in dollars per share)     $ 4.65
Options Outstanding, Number     629,136
Options Outstanding, Weighted Average Remaining Contractual Life     9 years 6 months 15 days
Weighted average exercise price of options outstanding (in dollars per share)     $ 1.28
Options Vested, Number     9,637
Options Vested, Weighted Average Remaining Contractual Life     9 years 22 days
Weighted average exercise price of options vested (in dollars per share)     $ 0.28
$6.75 - 15.79      
Information about stock options outstanding      
Exercise Price, low end of range (in dollars per share)     6.75
Exercise Price, high end of range (in dollars per share)     $ 15.79
Options Outstanding, Number     155,000
Options Outstanding, Weighted Average Remaining Contractual Life     10 years
Weighted average exercise price of options outstanding (in dollars per share)     $ 15.50