Annual report pursuant to Section 13 and 15(d)

Subsequent Events (Details)

v3.3.1.900
Subsequent Events (Details) - USD ($)
 1 Months Ended 12 Months Ended
Jul. 07, 2015
May. 08, 2015
Feb. 29, 2016
Dec. 31, 2015
Dec. 31, 2014
Subsequent Event.          
Proceeds from issuance of common stock, net       $ 90,310,634 $ 107,290,323
At-the-market sales facility          
Subsequent Event.          
Issuance of common stock (in shares) 1,000,000 2,700,000      
Proceeds from issuance of common stock, net $ 5,800,000 $ 16,200,000      
Subsequent event | At-the-market sales facility          
Subsequent Event.          
Issuance of common stock (in shares)     1,350,755    
Proceeds from issuance of common stock, net     $ 11,800,000    
Weighted-average | At-the-market sales facility          
Subsequent Event.          
Offering price (in dollars per share) $ 6.0001 $ 6.2503      
Weighted-average | Subsequent event | At-the-market sales facility          
Subsequent Event.          
Offering price (in dollars per share)     $ 9.00