XOMA Corporation Quarterly report pursuant to Section 13 or 15(d)

Royalty and Commercial Payment Purchase Agreements - Agenus (Details) $ in Thousands		1 Months Ended	9 Months Ended
	Sep. 20, 2018 USD ($) item	Nov. 30, 2020 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Agreements
Payments of consideration under RPAs, AAAs and CPPAs			$ 14,650	$ 8,000
Long-term royalty and commercial payment receivables			74,696		$ 63,683
Royalty Purchase Agreement \| Merck Immuno-Oncology Product \| Agenus
Agreements
Amount of milestone earned under agreement		$ 10,000
Agenus \| Royalty Purchase Agreement
Agreements
Payments of consideration under RPAs, AAAs and CPPAs	$ 15,000
Long-term royalty and commercial payment receivables	$ 15,000
Amount of allowance for credit losses			$ 0		$ 0
Agenus \| Royalty Purchase Agreement \| Incyte Immuno-Oncology Assets
Agreements
Royalties entity has right to receive (as a percent)	33.00%
Number of licensed products related to milestone and royalties \| item	6
Purchased percentage of milestones	10.00%
Agenus \| Royalty Purchase Agreement \| Merck Immuno-Oncology Product
Agreements
Royalties entity has right to receive (as a percent)	33.00%
Purchased percentage of milestones	10.00%
Purchased eligible milestone payments receivable upon achievement of potential development, regulatory and commercial milestones	$ 59,500
Amount of milestone earned under agreement		1,000
Reduction in long-term royalty receivable balance due to receipt of payment		$ 1,000