Royalty and Commercial Payment Purchase Agreements - Summary (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Royalty and Commercial Payment Purchase Agreements
Short-term royalty and commercial payment receivables	$ 12,682	$ 14,215
Long-term royalty and commercial payment receivables	$ 54,207	$ 57,952

Royalty and commercial payment receivables probable and reasonably estimable to be received after one year or beyond the normal operating cycle, if longer.

No definition available.

Name:	xoma_LongTermRightsReceivableNonCurrent
Namespace Prefix:	xoma_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant