Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Schedule of Options Activity (Details)

v3.19.1
Stock-Based Compensation - Schedule of Options Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Weighted Average Remaining Life (in years)        
Weighted Average Remaining Life (in years) 2 years 1 month 6 days      
Communicated Option Awards [Member]        
Options outstanding        
Beginning balance   933,500 933,500  
Granted   30,000    
Ending balance   963,500   933,500
Exercisable at the end of the period   769,507    
Vested and expected to vest at the end of the period   963,500    
Weighted Average Exercise Price        
Beginning balance   $ 3.92 $ 3.92  
Granted   25.00    
Ending balance   4.58   $ 3.92
Exercisable at the end of the period   3.19    
Vested and expected to vest at the end of the period   $ 4.58    
Weighted Average Remaining Life (in years)        
Weighted Average Remaining Life (in years)   4 years 8 months 15 days   3 years 6 months 25 days
Granted   10 years    
Exercisable at the end of the period   4 years    
Vested and expected to vest at the end of the period   4 years 8 months 15 days    
Aggregate Intrinsic Value        
Balance   $ 19,676 $ 19,676  
Balance   19,676   $ 19,676
Exercisable at the end of the period   14,015    
Vested and expected to vest at the end of the period   $ 19,676    
Stock Options [Member]        
Options outstanding        
Beginning balance 1,920,100      
Forfeited (12,000)      
Ending balance 1,908,100   1,920,100  
Exercisable at the end of the period 90,999      
Vested and expected to vest at the end of the period 1,908,100      
Weighted Average Exercise Price        
Beginning balance $ 28.59      
Forfeited 15.07      
Ending balance 28.68   $ 28.59  
Exercisable at the end of the period 28.94      
Vested and expected to vest at the end of the period $ 28.68      
Weighted Average Remaining Life (in years)        
Weighted Average Remaining Life (in years) 9 years 2 months 8 days   9 years 5 months 4 days  
Exercisable at the end of the period 9 years 2 months 4 days      
Vested and expected to vest at the end of the period 9 years 2 months 8 days