Quarterly report pursuant to Section 13 or 15(d)

Warrants - Summary of Warrant Activity (Details)

v3.19.2
Warrants - Summary of Warrant Activity (Details) - $ / shares
shares in Thousands
 6 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 3.48  
Warrants Outstanding (in shares) 8,378 10,055
Warrants Issued (in shares) 1,998  
Warrants expired (in shares) (3,675)  
Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 3.86  
Warrants Outstanding (in shares) 6,410 4,412
Warrants Issued (in shares) 1,998  
Warrants expired (in shares) 0  
Warrant Issued For | Derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 2.25  
Warrants Outstanding (in shares) 1,968 5,643
Warrants Issued (in shares) 0  
Warrants expired (in shares) (3,675)  
Financing | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 10.00  
Warrants Outstanding (in shares) 243 243
Warrants Issued (in shares) 0  
Warrants expired (in shares) 0  
Financing | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 15.00  
Warrants Outstanding (in shares) 276 276
Warrants Issued (in shares) 0  
Warrants expired (in shares) 0  
2017 Debt | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 0.92  
Warrants Outstanding (in shares) 443 443
Warrants Issued (in shares) 0  
Warrants expired (in shares) 0  
2015 Offering | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 5  
Warrants Outstanding (in shares) 3,450 3,450
Warrants Issued (in shares) 0  
Warrants expired (in shares) 0  
2019 Offering | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 0.2475  
Warrants Outstanding (in shares) 933 0
Warrants Issued (in shares) 933  
Warrants expired (in shares) 0  
2019 Offering | Warrant Issued With | Non-derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 0.253  
Warrants Outstanding (in shares) 1,065 0
Warrants Issued (in shares) 1,065  
Warrants expired (in shares) 0  
2016 Offerings | Warrant Issued For | Derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 2.25  
Warrants Outstanding (in shares) 1,968 1,968
Warrants Issued (in shares) 0  
Warrants expired (in shares) 0  
2017 Offering | Warrant Issued For | Derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 2.35  
Warrants Outstanding (in shares) 0 3,500
Warrants Issued (in shares) 0  
Warrants expired (in shares) (3,500)  
2017 Offering | Warrant Issued For | Derivative warrants    
Class of Warrant or Right [Line Items]    
Warrants Exercise Price (usd per share) $ 2.5  
Warrants Outstanding (in shares) 0 175
Warrants Issued (in shares) 0  
Warrants expired (in shares) (175)