Annual report pursuant to Section 13 and 15(d)

Selected Quarterly Financial Data (Unaudited) (Details)

v3.6.0.2
Selected Quarterly Financial Data (Unaudited) (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Selected Quarterly Financial Information [Line Items]                      
Loss from operations $ (10,204) $ (9,156) $ (9,311) $ (10,581) $ (11,393) $ (11,650) $ (9,730) $ (8,207)      
Net loss $ (2,472) $ (8,489) $ (5,764) $ (11,078) $ (11,296) $ (7,507) $ (13,623) $ (12,359) $ (27,255) $ (43,737) $ (19,784)
Net loss per share - basic (in dollars per share) $ (0.02) $ (0.09) $ (0.06) $ (0.12) $ (0.12) $ (0.08) $ (0.19) $ (0.17)      
Net loss per share - dilutive (in dollars per share) $ (0.02) $ (0.09) $ (0.10) $ (0.12) $ (0.12) $ (0.12) $ (0.19) $ (0.17)      
Weighted average common share - basic (in shares) 103,804,308 91,441,687 91,015,733 90,826,752 90,810,629 85,974,751 72,736,829 72,673,959      
Weighted average common share - dilutive (in shares) 103,804,308 91,441,687 93,930,540 90,826,752 90,810,629 87,585,103 72,736,829 72,673,959