Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Details)

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Stockholders' Equity (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Class of Stock [Line Items]      
Shares of common stock outstanding (in shares) 53,974,184   45,017,062
Shares of preferred stock outstanding (in shares) 2,907   4,963
Par value of common stock (in dollars per share) $ 0.001   $ 0.001
Par value of preferred stock (in dollars per share) $ 0.001   $ 0.001
Cash proceeds from option exercises $ 826 $ 0  
Cash proceeds from exercise of warrants $ 126 $ 0  
Preferred Stock      
Class of Stock [Line Items]      
Shares of preferred stock converted to common stock (in shares) 2,056    
Common Shares      
Class of Stock [Line Items]      
Shares of common stock issued upon conversion of preferred stock (in shares) 2,056,000    
Cash proceeds from option exercises $ 800    
Cash proceeds from exercise of warrants $ 100    
Common Shares | Options      
Class of Stock [Line Items]      
Shares of common stock issued upon exercises (in shares) 512,960 0  
Common Shares | Warrants      
Class of Stock [Line Items]      
Shares of common stock issued upon exercises (in shares) 63,162 0