Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Additional Information (Details)

v3.19.2
Stock-based Compensation - Additional Information (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Number of shares exercised 54,720  
Unamortized stock-based compensation cost related to unvested stock options $ 707  
Unamortized stock-based compensation cost, weighted average period of recognition 3 years  
2012 Equity Incentive Plan    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Number of shares available to be issued 459,075  
Expiration period 10 years  
Number of shares exercised 0 0
2012 Equity Incentive Plan | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Vesting period 2 years  
2012 Equity Incentive Plan | Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Vesting period 4 years  
2012 Equity Incentive Plan | Options and SARs | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Exercise price options granted from fair value common stock, percent 100.00%  
2012 Equity Incentive Plan | Granted to Ten Percent Stockholders | Minimum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Exercise price options granted from fair value common stock, percent 110.00%  
2012 Equity Incentive Plan | Granted to Ten Percent Stockholders | Maximum    
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Vesting period 5 years