XML 61 R68.htm IDEA: XBRL DOCUMENT
v3.20.1

Stock-based Compensation - ESPP (Details) | 3 Months Ended
--- | ---
Mar. 31, 2020
2015 ESPP |
Share-based compensation |
Percentage related to employees to purchase shares at the lower fair market value at offering period | 85.00%

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Purchase price of common stock expressed as a percentage of its fair value. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePriceOfCommonStockPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_PlanNameAxis=xoma_TwoThousandFifteenEmployeeStockPurchasePlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |