Quarterly report pursuant to Section 13 or 15(d)

Description of Business - Additional Information (Details)

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Description of Business - Additional Information (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended
Oct. 31, 2016
$ / shares
Mar. 31, 2017
USD ($)
$ / shares
Dec. 31, 2016
USD ($)
$ / shares
Mar. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Description Of Business [Abstract]          
Accumulated deficit   $ 1,204,370 $ 1,193,613 [1]    
Working capital deficiency   600      
Carrying value of the loan   26,629      
Cash and cash equivalents   $ 20,045 $ 25,742 [1] $ 46,153 $ 65,767
Reverse stock split, description   In October 2016, the Company’s stockholders voted at a special meeting of stock holders to approve a series of alternate amendments to the Company’s Amended Certificate of Incorporation to effect a reverse stock split of the Company’s issued and outstanding common stock. The Company’s Board of Directors then approved a specific ratio of 1-for-20.      
Reverse stock split ratio 0.05        
Common stock, par value per share | $ / shares $ 0.0075 $ 0.0075 $ 0.0075    
[1] The condensed consolidated balance sheet as of December 31, 2016 has been derived from the audited consolidated financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.