Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
6 Months Ended
Jun. 30, 2019
Aug. 02, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name XOMA Corp  
Trading Symbol XOMA  
Entity Central Index Key 0000791908  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   8,727,617
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q2  
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Jun. 30, 2019  
Entity Current Reporting Status Yes  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Tax Identification Number 522154066  
Entity File Number 0-14710  
Entity Address, Address Line One 2200 Powell Street  
Entity Address, Address Line Two Suite 310  
Entity Address, City or Town Emeryville  
Entity Address, State or Province California  
Entity Address, Postal Zip Code 94608  
City Area Code (510)  
Local Phone Number 204-7200