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

Capital Stock - Summary of Common Stock Warrants Outstanding (Details) - $ / shares	1 Months Ended	12 Months Ended
	Feb. 29, 2016	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2012
Class Of Warrant Or Right [Line Items]
Expiration Date	2021-02
Exercise price of warrants (in dollars per share)	$ 15.40
Number of Shares		17,312	498,556
Five Year Warrants Issued in March 2012 [Member]
Class Of Warrant Or Right [Line Items]
Exercise price of warrants (in dollars per share)				$ 35.20
Five Year Warrants Issued in March 2012 [Member] \| Contingent Warrant Liability [Member]
Class Of Warrant Or Right [Line Items]
Issuance Date		2012-03
Expiration Date		2017-03
Exercise price of warrants (in dollars per share)		$ 35.20
Number of Shares			479,277
Five Year Warrants Issued in September 2012 [Member] \| Stockholders' Equity (Deficit) [Member]
Class Of Warrant Or Right [Line Items]
Issuance Date		2012-09
Expiration Date		2017-09
Exercise price of warrants (in dollars per share)		$ 70.80
Number of Shares			1,967
Five Year Warrants Issued in February 2015 [Member] \| Stockholders' Equity (Deficit) [Member]
Class Of Warrant Or Right [Line Items]
Issuance Date		2015-02
Expiration Date		2020-02
Exercise price of warrants (in dollars per share)		$ 66.20
Number of Shares		9,063	9,063
Five Year Warrants Issued in February 2016 [Member] \| Stockholders' Equity (Deficit) [Member]
Class Of Warrant Or Right [Line Items]
Issuance Date		2016-02
Expiration Date		2021-02
Exercise price of warrants (in dollars per share)		$ 15.40
Number of Shares		8,249	8,249