Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation and Warrants (Details Textual)

v3.8.0.1
Stock-Based Compensation and Warrants (Details Textual) - USD ($)
1 Months Ended 12 Months Ended
Oct. 10, 2014
Nov. 18, 2016
Oct. 25, 2012
Mar. 20, 2007
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Sep. 07, 2017
Aug. 25, 2016
May 15, 2015
Oct. 22, 2013
Nov. 02, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options         $ 2,900,000              
Proceeds from Issuance of Common Stock   $ 300,000     0 $ 25,000,000 $ 46,000,000          
Change in fair value of warrant liabilities         (10,738,000) (11,412,000) 3,811,000          
Proceeds from Stock Options Exercised         166,000 814,000 $ 41,000          
IPO [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Sale of Stock, Price Per Share   $ 1.00                    
Change in fair value of warrant liabilities         9,000,000 3,000,000            
Stock Issued During Period, Shares, New Issues   25,000,000                    
Class of Warrant or Right, Number of Securities Called by Warrants or Rights   50,000,000                    
Warrants Not Settleable in Cash, Fair Value Disclosure   $ 15,700,000     $ 3,700,000 $ 12,700,000            
Series A Warrants [Member] | IPO [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 1.43                    
Series B Warrants [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Investment Warrants Expiration Date   Dec. 31, 2017     Dec. 31, 2017              
Series B Warrants [Member] | IPO [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Investment Warrants Expiration Date   Dec. 31, 2017                    
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 1.72                    
Warrant [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Issuance of Warrants to Purchase of Common Stock     635,855                  
Warrants Exercise Price Per Share     $ 1.60                  
Employees And Directors [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross         3,159,177 3,861,425 3,781,666          
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Fair Value         $ 1,800,000 $ 3,100,000 $ 8,000,000          
Employee [Member] | General and Administrative Expenses and Research and Development Expense [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Allocated Share-based Compensation Expense         3,000,000 3,400,000 2,300,000          
Consultant [Member] | General and Administrative Expenses and Research and Development Expense [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Allocated Share-based Compensation Expense         $ 434,000 603,000 $ 888,000          
2007 Stock Plan [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number       2,500,000 712,258              
2007 Stock Plan [Member] | Maximum [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross       250,000                
2010 Stock Plan [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number         11,851,840             3,000,000
2010 Stock Plan [Member] | Maximum [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Common Stock, Capital Shares Reserved for Future Issuance               17,500,000 14,000,000 8,000,000 6,000,000  
2010 Stock Plan [Member] | Minimum [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Common Stock, Capital Shares Reserved for Future Issuance               8,000,000 8,000,000 6,000,000 3,000,000  
Stock Warrants [Member]                        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                        
Issuance of Warrants to Purchase of Common Stock 0.5                      
Share-based Compensation Arrangement by Share-based Payment Award, Warrants, Exercisable Number 7,029,808                      
Share-based Compensation Arrangement by Share-based Payment Award, Warrants, Vested and Expected to Vest Outstanding, Number 1.75                      
Sale of Stock, Number of Shares Issued in Transaction 14,059,616                      
Sale of Stock, Price Per Share $ 1.47                      
Proceeds from Issuance of Common Stock $ 19,100,000                      
Change in fair value of warrant liabilities $ 7,400,000       $ 1,700,000 8,500,000            
Warrants Not Settleable in Cash, Fair Value Disclosure         $ 416,000 $ 2,100,000