Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Private Placement and Preferred Stock (Details)

v3.8.0.1
Stockholders' Equity - Private Placement and Preferred Stock (Details)
$ / shares in Units, $ in Millions
 1 Months Ended
Jun. 30, 2016
USD ($)
$ / shares
shares
Dec. 31, 2017
$ / shares
shares
Dec. 31, 2016
$ / shares
shares
Class of Stock [Line Items]      
Number of shares per unit (in shares) 1    
Warrant exercise period 5 years    
Par value of preferred stock (in dollars per share) | $ / shares $ 0.001 $ 0.001 $ 0.001
Shares of common stock issued (in shares)   45,017,062 43,058,827
Shares of preferred stock issued (in shares)   4,963 4,963
Shares of preferred stock outstanding (in shares)   4,963 4,963
Preferred Stock      
Class of Stock [Line Items]      
Percentage of beneficial ownership 9.99%    
Securities Purchase Agreement      
Class of Stock [Line Items]      
Number of capital units sold in private placement transaction (in units) 8,188,804    
Gross proceeds from private placement units sold | $ $ 16.5    
Net proceeds from private placement units sold | $ $ 15.3    
Issue price per share of preferred stock (in dollars per share) | $ / shares $ 2.015    
2016 PIPE      
Class of Stock [Line Items]      
Shares of common stock issued (in shares) 3,225,804    
Series A Convertible Preferred Stock      
Class of Stock [Line Items]      
Price per unit issued (in dollars per share) | $ / shares $ 2.015    
Number of shares per unit (in shares) 1    
Shares issued upon conversion of convertible preferred stock (in shares) 1,000    
Series A Convertible Preferred Stock | Private Placement | 2016 PIPE      
Class of Stock [Line Items]      
Shares of preferred stock issued (in shares) 4,963    
Tranche A Warrants      
Class of Stock [Line Items]      
Number of warrants 1    
Number of shares to be purchased by a warrant (in shares) 0.4    
Exercise price (in dollars per share) | $ / shares $ 2.00    
Tranche B Warrants      
Class of Stock [Line Items]      
Number of warrants 1    
Number of shares to be purchased by a warrant (in shares) 0.2    
Exercise price (in dollars per share) | $ / shares $ 3.00