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 6 Months Ended
Nov. 18, 2016
Oct. 10, 2014
Oct. 25, 2012
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Dec. 31, 2016
Mar. 31, 2016
Equity, Class of Treasury Stock [Line Items]                  
Change in fair value of warrant liability       $ (2,159) $ (3,513) $ (7,249) $ (3,015)    
Warrant liabilities       $ 7,573   $ 7,573   $ 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   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 liability   $ 7,400   $ 200 $ 3,500 $ 1,100 $ 3,000    
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              
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       1,000   1,000     $ 7,600
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     6,600   6,600      
Change in fair value of warrant liability       $ 2,000   $ 6,100      
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