XOMA Corporation Annual report pursuant to Section 13 and 15(d)

Dispositions - Additional Information (Details)

Dispositions - Additional Information (Details) - USD ($)				3 Months Ended	12 Months Ended
	Dec. 31, 2015	Nov. 05, 2015	Nov. 04, 2015	Dec. 31, 2015	Dec. 31, 2015
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on sale of business					$ 3,505,000
Biodefense Business [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Sales of business, number of common stock shares eligible to receive			23,008
Royalties receivable percentage on net sales			15.00%
Biodefense Business [Member] \| Maximum [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash payments from Nanotherapeutics			$ 4,500,000
Manufacturing Facility in Berkeley, California [Member] \| Other Income (Expense), Net [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on sale of business				$ 3,500,000
Manufacturing Facility in Berkeley, California [Member] \| Agenus Purchase Agreement [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash received from sale of business	$ 4,700,000
Sale of business, value of common stock shares received	500,000			500,000	500,000
Liabilities assumed	$ 300,000
Sales of business, number of common stock shares received	109,211
Contingent consideration value of common stock to be received					500,000
Consideration received for employees who would not have otherwise been retained					200,000
Carrying value of business sold	$ 2,200,000			$ 2,200,000	2,200,000
Manufacturing Facility in Berkeley, California [Member] \| Agenus Purchase Agreement [Member] \| Other Income (Expense), Net [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on sale of business					$ 3,500,000
Manufacturing Facility in Berkeley, California [Member] \| Maximum [Member] \| Agenus Purchase Agreement [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Cash received from sale of business		$ 5,000,000
Sale of business, value of common stock shares received		$ 1,000,000