Annual report pursuant to Section 13 and 15(d)

Concentration of Risk, Segment and Geographic Information (Details)

v2.4.1.9
Concentration of Risk, Segment and Geographic Information (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Segment
Dec. 31, 2013
Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Number of operating segments                 1us-gaap_NumberOfOperatingSegments    
Revenues $ 4,347us-gaap_Revenues $ 5,136us-gaap_Revenues $ 5,973us-gaap_Revenues $ 3,410us-gaap_Revenues $ 12,535us-gaap_Revenues $ 6,312us-gaap_Revenues $ 7,151us-gaap_Revenues $ 9,453us-gaap_Revenues $ 18,866us-gaap_Revenues $ 35,451us-gaap_Revenues $ 33,782us-gaap_Revenues
United States [Member] | Reportable Geographical Components [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues                 11,756us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= country_US
19,955us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= country_US
14,134us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= country_US
Europe [Member] | Reportable Geographical Components [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues                 5,510us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
15,396us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
18,454us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_EuropeMember
Asia Pacific [Member] | Reportable Geographical Components [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Revenues                 $ 1,600us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaPacificMember
$ 100us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaPacificMember
$ 1,194us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_ReportableGeographicalComponentsMember
/ us-gaap_StatementGeographicalAxis
= us-gaap_AsiaPacificMember
Revenues [Member] | Customer Concentration Risk [Member]                      
Concentration Risk [Line Items]                      
Number of major customers                 2xoma_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
3xoma_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
 
Revenues [Member] | Customer Concentration Risk [Member] | Customer 1 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                 51.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer1Member
43.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer1Member
 
Revenues [Member] | Customer Concentration Risk [Member] | Customer 2 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                 28.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer2Member
26.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer2Member
 
Revenues [Member] | Customer Concentration Risk [Member] | Customer 3 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                   20.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_SalesRevenueGoodsNetMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer3Member
 
Accounts Receivable [Member] | Customer Concentration Risk [Member]                      
Concentration Risk [Line Items]                      
Number of major customers                 3xoma_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
2xoma_NumberOfMajorCustomers
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
 
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer 1 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                 44.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer1Member
73.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer1Member
 
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer 2 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                 34.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer2Member
13.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer2Member
 
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer 3 [Member]                      
Concentration Risk [Line Items]                      
Concentration risk, percentage (in hundredths)                 12.00%us-gaap_ConcentrationRiskPercentage1
/ us-gaap_ConcentrationRiskByBenchmarkAxis
= us-gaap_AccountsReceivableMember
/ us-gaap_ConcentrationRiskByTypeAxis
= us-gaap_CustomerConcentrationRiskMember
/ us-gaap_MajorCustomersAxis
= xoma_Customer3Member