Quarterly report pursuant to Section 13 or 15(d)

Stock Purchase Warrants (Details Textual)

v3.7.0.1
Stock Purchase Warrants (Details Textual) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended
Nov. 18, 2016
Oct. 10, 2014
Oct. 25, 2012
Mar. 31, 2017
Mar. 31, 2016
Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]            
Change in fair value of warrant liabilities       $ (5,090) $ 498  
Warrant liabilities       $ 9,731   $ 14,821
Warrant [Member]            
Equity, Class of Treasury Stock [Line Items]            
Issuance Of Warrants To Purchase Of Common Stock     635,855      
Warrants Exercise Price Per Share     $ 1.60      
Class of Warrant or Right, Outstanding       311,834    
Stock Warrants [Member]            
Equity, Class of Treasury Stock [Line Items]            
Sale of Stock, Price Per Share   $ 1.47        
Change in fair value of warrant liabilities   $ 7,400   $ 1,000    
Proceeds from Issuance of Common Stock   $ 19,100        
Sale of Stock, Number of Shares Issued in Transaction   14,059,616        
Issuance Of Warrants To Purchase Of Common Stock   0.5     500,000  
Share-Based Compensation Arrangement By Share-Based Payment Award, Options, Exercisable, Number   7,029,808        
Share Based Compensation Arrangement By Share Based Payment Award Warrants Vested and Expected To Vest Outstanding Number   1.75        
Warrant liabilities       1,100 $ 11,100  
IPO [Member]            
Equity, Class of Treasury Stock [Line Items]            
Sale of Stock, Price Per Share $ 1.00          
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     8,600    
Change in fair value of warrant liabilities       $ 4,100    
IPO [Member] | Series A [Member]            
Equity, Class of Treasury Stock [Line Items]            
Class of Warrant or Right, Exercise Price of Warrants or Rights $ 1.43          
IPO [Member] | Series B [Member]            
Equity, Class of Treasury Stock [Line Items]            
Class of Warrant or Right, Exercise Price of Warrants or Rights $ 1.72          
Investment Warrants Expiration Date1 Dec. 31, 2017