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

Annual report pursuant to Section 13 and 15(d)

Capital Stock, Other Offerings and Agreements (Details)

Capital Stock, Other Offerings and Agreements (Details) (USD $)	0 Months Ended	1 Months Ended	12 Months Ended			1 Months Ended	11 Months Ended	0 Months Ended	1 Months Ended
	Mar. 09, 2012	May 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2009	Dec. 31, 2011	Dec. 08, 2014	Dec. 31, 2013	Aug. 31, 2013	Oct. 31, 2012	Feb. 28, 2010	Aug. 23, 2013	Oct. 29, 2012
Registered Direct Offerings and Underwritten Offering [Abstract]
Capital units issued upon the underwriters 30-day over-allotment option (in shares)				1,425,000					1,425,000
Offering expense	$ 3,000,000xoma_OfferingCosts
Offering price (in dollars per share)								$ 4.94us-gaap_SharePrice
Common stock, shares authorized (in shares)		277,333,332us-gaap_CommonStockSharesAuthorized	277,333,332us-gaap_CommonStockSharesAuthorized	138,666,666us-gaap_CommonStockSharesAuthorized					138,666,666us-gaap_CommonStockSharesAuthorized
Common stock, par value (in dollars per share)		$ 0.0075	$ 0.0075	$ 0.0075					$ 0.0075
Additional common shares authorized for issuance (in shares)		138,666,666
ATM Agreement [Abstract]
Proceeds from issuance of common stock			41,442,000	84,338,000	76,498,000
Registered Direct Offerings [Member]
Registered Direct Offerings and Underwritten Offering [Abstract]
Capital units issued (in shares)						695,652
Common stock per capital unit (in shares)						1
Common stock per capital unit called by stock warrant (in shares)						0.50
Gross proceeds from issuance of capital units						12,000,000
Offering expense						800,000
Purchase price of capital units (in dollars per share)						$ 17.25
Number of shares called by warrants (in shares)						347,826
Exercise price of warrants (in dollars per share)						$ 19.50
2011 ATM Agreement [Member]
ATM Agreement [Abstract]
Common stock sold (in shares)				0			7,572,327
Sales commission paid per transaction (in hundredths)							3.00%
Proceeds from issuance of common stock				500,000			14,600,000
Underwritten Offering [Member]
Registered Direct Offerings and Underwritten Offering [Abstract]
Capital units issued (in shares)	29,669,154			10,925,000					10,925,000			2,800,000	8,736,187	13,333,333
Capital units issued upon the underwriters 30-day over-allotment option (in shares)													1,139,502
Common stock per capital unit (in shares)	0.5							1				1
Common stock per capital unit called by stock warrant (in shares)												0.45
Gross proceeds from issuance of capital units	39,200,000							40,000,000	57,400,000	31,600,000	40,000,000	21,000,000
Offering expense								$ 2,300,000	$ 3,800,000	$ 2,200,000	$ 3,000,000
Purchase price of capital units (in dollars per share)	$ 1.32			$ 5.25					$ 5.25				$ 3.62	$ 3.00
Number of shares called by warrants (in shares)	14,834,577
Immediate term for warrants exercisable (in years)	5 years							2 years
Exercise price of warrants (in dollars per share)	$ 1.76							$ 7.90
Period to purchase additional stock									30 days	30 days
Warrant outstanding (in shares)	12,109,418							8,097,165