Quarterly report pursuant to Section 13 or 15(d)

Document And Entity Information

Document And Entity Information (USD $)
6 Months Ended
Jun. 30, 2011
Aug. 02, 2011
Jun. 30, 2010
Entity Registrant Name XOMA LTD /DE/    
Entity Central Index Key 0000791908    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 104,378,157
Entity Common Stock, Shares Outstanding   32,554,155  
Document Fiscal Year Focus 2011    
Document Fiscal Period Focus Q2    
Document Type 10-Q    
Amendment Flag false    
Document Period End Date Jun. 30, 2011