Quarterly report pursuant to Section 13 or 15(d)

Description of Business - Additional Information (Details)

v3.3.0.814
Description of Business - Additional Information (Details) - USD ($)
$ in Thousands
 9 Months Ended
Sep. 30, 2015
Dec. 31, 2014
Sep. 30, 2014
Dec. 31, 2013
Description Of Business [Line Items]        
Accumulated deficit $ (1,165,435) $ (1,119,477) [1]    
Cash and cash equivalents 32,046 78,445 [1] $ 54,060 $ 101,659
Novartis Note [Member]        
Description Of Business [Line Items]        
Outstanding principal balance $ 13,500 $ 13,400    
Maturity date Jun. 30, 2015      
Collaborative Arrangement | Novartis Note [Member]        
Description Of Business [Line Items]        
Upfront payment received $ 37,000      
Outstanding principal balance $ 13,500      
Maturity date Sep. 30, 2020      
[1] The condensed consolidated balance sheet as of December 31, 2014 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, 2014.