XOMA Corporation Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

Licensing and Other Arrangements - Rezolute - Additional Information (Details)

Licensing and Other Arrangements - Rezolute - Additional Information (Details) - Rezolute [Member]							1 Months Ended			3 Months Ended	6 Months Ended	12 Months Ended		18 Months Ended		21 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Jan. 30, 2019 USD ($)	Jan. 07, 2019 USD ($) CashPayment	Apr. 03, 2018 USD ($) Obligation shares	Dec. 06, 2017 USD ($) shares	Feb. 28, 2019 USD ($)	Apr. 30, 2018 USD ($) shares	Mar. 31, 2018 USD ($) shares	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2020 shares	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)	Jun. 01, 2019 USD ($)	Sep. 30, 2020 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contract revenue										$ 0
License Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Future milestone payments, maximum						$ 232,000,000									$ 237,000,000
Upfront option fee															$ 1,000,000
Agreement termination notice period						90 days
Reimbursable technology transfer expenses received					$ 300,000
Common stock value receivable				$ 8,500,000
Number of future cash payments upon closing of the qualified financing \| CashPayment				5
Percentage of net proceeds of each future financing upon closing of the qualified financing				15.00%
License Agreement [Member] \| Forecast [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Future cash payments upon closing of the qualified financing																$ 8,500,000
License Agreement and Common Stock Purchase Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible to receive in cash									$ 6,000,000
Eligible to receive common stock, financing activities									$ 8,500,000
Eligible to receive shares of common stock \| shares									7,000,000
Gross proceeds from qualified financing		$ 20,000,000
Additional common stock receive for qualified financing		$ 8,500,000
Common stock, trading period		10 days
Contract revenue											$ 8,000,000
Common stock received \| shares					8,093,010
Cash received					$ 500,000
Reimbursable technology transfer expenses received					$ 300,000
Number of performance obligations \| Obligation					1
Upfront consideration to incremental discount for future payment					$ 0
Remaining performance obligations					0
License agreement transaction price					1,800,000
Value of common stock received					$ 1,000,000
Contract assets											0		$ 0
Contract liabilities											0		0
Capitalized contract costs											0		0
Doubtful revenue reversal of future cash payments											2,500,000
Consideration due upon qualified financing event											5,500,000
Future cash payments of revenue recognized											2,500,000
Outstanding receivable											$ 2,500,000
License Agreement and Common Stock Purchase Agreement [Member] \| Licenses and Related Materials, Product Data/Filing, Process and Know-how [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Recognized the entire transaction price as revenue upon completion of delivery													$ 1,800,000
License Agreement and Common Stock Purchase Agreement [Member] \| Forecast [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible to receive, in order to maintain license agreement	$ 15,000,000
Future cash payments upon closing of the qualified financing														$ 2,900,000		$ 8,500,000
Common Stock Purchase Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of shares of common stock held for future issuance \| shares						5,000,000
Common stock purchase agreement description											Under the common stock purchase agreement, Rezolute granted the Company the right and option to sell the greater of (i) 5,000,000 shares of common stock or (ii) one third of the aggregate shares held by the Company upon failure by Rezolute to list its shares of its common stock on the Nasdaq Stock Market or a similar national exchange on or prior to December 31, 2018.
Percentage of aggregate shares held for future issuance						33.33%
Cash received							$ 5,500,000
Reimbursable technology transfer expenses received							$ 300,000
Gross proceeds from preferred stock financing			$ 25,000,000
Common Stock Purchase Agreement [Member] \| Interim Financing Closing and Initial Closing Financing Activities [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Common stock received \| shares								8,093,010
Cash received								$ 500,000
Common Stock Purchase Agreement [Member] \| Forecast [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Maximum number of shares of common stock sold back \| shares												5,000,000
Number of shares of common stock sold back \| shares												2,500,000