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

Annual report pursuant to Section 13 and 15(d)

Subsequent Event - Additional Information (Details)

Subsequent Event - Additional Information (Details) $ / shares in Units, $ in Millions							1 Months Ended		12 Months Ended
	Mar. 04, 2019 $ / shares shares	Feb. 25, 2019 Agreement	Jan. 07, 2019 USD ($) CashPayment	May 07, 2018 $ / shares shares	Apr. 14, 2018 Facility	Nov. 21, 2017 Facility	Jan. 31, 2019 USD ($) Facility	Oct. 31, 2018 USD ($) Facility	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Subsequent Event [Line Items]
Operating leases, number of portions of leased facilities \| Facility					1	1		1
Operating leases, number of leased facilities \| Facility					3	3		3
Operating leases, sublease commencement date					May 01, 2018	Dec. 26, 2017		Oct. 24, 2018
Operating leases sublease income receivable								$ 1.7
Operating leases sublease expiry date					2023-04	2023-04		2021-05
Loan and Security Agreement [Member] \| Silicon Valley Bank [Member] \| Warrants for Common Stock [Member]
Subsequent Event [Line Items]
Earlier effecitve date of term loan				Mar. 31, 2019
Aggregate number of unregistered shares of common stock called by warrants (in shares) \| shares				6,332
Exercise price of warrants (in dollars per share) \| $ / shares				$ 23.69
Exercisable period of warrants				10 years
Subsequent Event [Member] \| Sublease Agreement [Member]
Subsequent Event [Line Items]
Operating leases, number of portions of leased facilities \| Facility							1
Operating leases, number of leased facilities \| Facility							3
Operating leases, sublease commencement date							Jan. 18, 2019
Operating leases sublease income receivable							$ 1.7
Operating leases sublease expiry date							2023-04
Subsequent Event [Member] \| Loan and Security Agreement [Member] \| Silicon Valley Bank [Member] \| Warrants for Common Stock [Member]
Subsequent Event [Line Items]
Effective date of term loan extended	Mar. 31, 2020
Aggregate number of unregistered shares of common stock called by warrants (in shares) \| shares	4,845
Exercise price of warrants (in dollars per share) \| $ / shares	$ 14.71
Exercisable period of warrants	10 years
Subsequent Event [Member] \| Rezolute [Member] \| License Agreement [Member]
Subsequent Event [Line Items]
Number of future cash payments upon closing of the qualified financing \| CashPayment			5
Future cash payments upon closing of the qualified financing			$ 8.5
Percentage of net proceeds of each future financing upon closing of the qualified financing			15.00%
Additional cash receipts upon closing of qualified financing			$ 5.5
Subsequent Event [Member] \| Bioasis Technologies Inc [Member] \| Royalty Purchase Agreement [Member]
Subsequent Event [Line Items]
Percentage of Option to purchase royalty right on future license agreements		1.00%
Number of license agreements \| Agreement		2
Cooley [Member]
Subsequent Event [Line Items]
Payments to related party									$ 0.7	$ 1.5
Cooley [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Percentage of related party payment on related party gross revenues									5.00%