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) - USD ($)
$ in Thousands
1 Months Ended
Sep. 22, 2017
Aug. 24, 2017
Sep. 30, 2015
Aug. 31, 2017
Sep. 30, 2017
Dec. 31, 2016
[1]
Sep. 30, 2016
Dec. 31, 2015
Description Of Business [Line Items]                
Accumulated deficit         $ 1,177,740 $ 1,193,613    
Working capital         34,900      
Carrying value of the loan         14,300      
Cash and cash equivalents         $ 47,747 $ 25,742 $ 20,618 $ 65,767
Secured Note Amendment [Member]                
Description Of Business [Line Items]                
Maturity date     Sep. 30, 2020          
Secured Note Amendment [Member] | XOMA-052 License Agreement [Member]                
Description Of Business [Line Items]                
Maturity date Sep. 30, 2022   Sep. 30, 2020          
Novartis Pharma AG [Member]                
Description Of Business [Line Items]                
Cash proceeds received       $ 25,700        
Cash proceeds from sale of shares   $ 5,000            
[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.