XML 62 R41.htm IDEA: XBRL DOCUMENT
v3.20.1

Consolidated Financial Statements Detail - Equity Securities (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018
Equity Securities |  |
Equity securities | $ 681 | $ 392
Change in fair value of equity securities | 289 | $ (563)
Rezolute |  |
Equity Securities |  |
Equity securities | 700 |
Change in fair value of equity securities | $ 300 |

X
- Definition Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 321 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714 + Details
Name: | us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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_ScheduleOfTradingSecuritiesAndOtherTradingAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity securities FvNi non current. + References No definition available. + Details
Name: | xoma_EquitySecuritiesFvNiNonCurrent
Namespace Prefix: | xoma_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=xoma_RezoluteIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |