Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Restricted Cash, Concentration Risk, and Potentially Dilutive Securities (Details)

v3.10.0.1
Summary of Significant Accounting Policies - Restricted Cash, Concentration Risk, and Potentially Dilutive Securities (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 20,892 $ 22,793 $ 25,458 $ 20,141
Restricted cash     1,124 11,667
Cash and cash equivalents $ 20,892 $ 22,793 $ 26,582 $ 31,808
Total potential dilutive securities 4,833,766 3,802,839 5,420,391  
Restricted Stock (in shares)        
Total potential dilutive securities 96,623 180,951    
Consulting Warrants (in shares)        
Total potential dilutive securities   0 486,364  
Employee Stock Option (in shares)        
Total potential dilutive securities 1,694,068 578,813 915,572  
Warrant (in shares)        
Total potential dilutive securities 2,340,828 2,340,828 3,316,208  
Convertible Notes Payable (in shares)        
Total potential dilutive securities 702,247 702,247 702,247  
Customer Concentration Risk | Sales Revenue, Net        
Concentration risk, percentage 88.00% 96.10% 0.00%  
Customer Concentration Risk | Accounts Receivable        
Concentration risk, percentage 94.80% 95.40%