Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

Document and Entity Information - shares
9 Months Ended
Sep. 30, 2020
Nov. 02, 2020
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2020  
Document Transition Report false  
Entity File Number 0-14710  
Entity Registrant Name XOMA Corporation  
Entity Incorporation State Country Code DE  
Entity Tax Identification Number 52-2154066  
Entity Address Address Line1 2200 Powell Street  
Entity Address Address Line2 Suite 310  
Entity Address City Or Town Emeryville  
Entity Address State Or Province CA  
Entity Address Postal Zip Code 94608  
City Area Code 510  
Local Phone Number 204-7200  
Security12b Title Common Stock  
Trading Symbol XOMA  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   11,022,143
Entity Central Index Key 0000791908  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q3  
Amendment Flag false