Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Summary of stock option activity (Details)

v3.19.2
Stock-Based Compensation - Summary of stock option activity (Details) - Stock Option [Member] - USD ($)
6 Months Ended 12 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Options, Beginning Balance 938,982 359,076  
Options, Granted   671,500  
Options, Expired (52,419) (78,667)  
Options, Forfeited (43,444) (12,927)  
Options, Ending Balance 843,119 938,982 359,076
Options, Exercisable 289,660    
Weighted Average Exercise Price, Beginning Balance $ 15.18 $ 53.93  
Weighted Average Exercise Price, Granted   0.69  
Weighted Average Exercise Price, Expired 68.96 67.02  
Weighted Average Exercise Price, Forfeited 8.30 23.72  
Weighted Average Exercise Price, Ending Balance 12.19 $ 15.18 $ 53.93
Weighted Average Exercise Price, Exercisable $ 32.81    
Weighted Average Remaining Contractual Life, Balance Outstanding 5 years 10 months 6 days 6 years 2 months 9 days 4 years 7 months 6 days
Weighted Average Remaining Contractual Life, Exercisable 4 years 9 months 18 days    
Aggregate Intrinsic Value, Ending Balance $ 0 $ 0 $ 1,800
Aggregate Intrinsic Value, Exercisable 0    
Grant date fair value of options granted $ 0 $ 301,000  
Weighted average grant date fair value $ 0 $ 0.45