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

Fair Value Measurements - Outstanding Debt Carrying Amount and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing obligations, Carrying amount	$ 48,667	$ 35,308
Interest bearing obligations, Fair value	49,810	36,461
Hercules Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing obligations, Carrying amount	19,653
Interest bearing obligations, Fair value	21,231
Servier Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing obligations, Carrying amount	15,331	16,290
Interest bearing obligations, Fair value	15,185	17,068
Novartis Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing obligations, Carrying amount	13,683	13,357
Interest bearing obligations, Fair value	$ 13,394	12,923
General Electric Capital Corporation Term Loan [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest-bearing obligations, Carrying amount		5,661
Interest bearing obligations, Fair value		$ 6,470