XML 42 R31.htm IDEA: XBRL DOCUMENT
v3.21.2

Description of Business - Stock Issuance (Details) - shares |  |  | 9 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Apr. 09, 2021 | Dec. 15, 2020 | Sep. 30, 2021 | Dec. 31, 2020
8.625% Series A Cumulative, Perpetual Preferred Stock |  |  |  |
Stock |  |  |  |
Preferred stock, dividend rate (as a percent) |  | 8.625% | 8.625% | 8.625%
8.375% Series B Cumulative, Perpetual Preferred Stock |  |  |  |
Stock |  |  |  |
Preferred stock, dividend rate (as a percent) | 8.375% |  | 8.375% | 8.375%
Depositary share's fractional interest in share of preferred stock | 0.001 |  | 0.001 |

X
- Definition The percentage rate used to calculate dividend payments on preferred stock. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644 + Details
Name: | us-gaap_PreferredStockDividendRatePercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
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_SubsidiarySaleOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents depositary share's fractional interest in share of preferred stock. + References No definition available. + Details
Name: | xoma_DepositarySharesRatioToPreferredStock
Namespace Prefix: | xoma_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesAPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesBPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |