Description of Business - Additional Information (Details) $ in Thousands |
9 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Oct. 17, 2016 |
Oct. 14, 2016 |
Sep. 30, 2016
USD ($)
|
Dec. 31, 2015
USD ($)
|
[1] |
Sep. 30, 2015
USD ($)
|
Dec. 31, 2014
USD ($)
|
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| Description Of Business [Line Items] | |||||||||
| Accumulated deficit | $ (1,176,133) | $ (1,140,083) | |||||||
| Cash and cash equivalents | $ 20,618 | $ 65,767 | $ 32,046 | $ 78,445 | |||||
| Reverse stock split, description | In October 2016, the Company’s stockholders voted at a special meeting of stock holders to approve a series of alternate amendments to the Company’s Amended Certificate of Incorporation to effect a reverse stock split of the Company’s issued and outstanding common stock. The Company’s Board of Directors then approved a specific ratio of 1-for-20. | ||||||||
| Subsequent Event [Member] | |||||||||
| Description Of Business [Line Items] | |||||||||
| Reverse stock split, description | Upon the effectiveness of the reverse stock split, (i) every 20 shares of the Company’s outstanding common stock was combined into 1 share of common stock, (ii) the number of shares of common stock available for issuance under the 2010 Plan and ESPP was proportionally decreased, (iii) the number of shares of common stock issuable upon the exercise of the outstanding stock options and warrants was proportionally decreased, (iv) the exercise price of the outstanding stock options and warrants was proportionally increased, and (v) the number of shares of common stock issuable upon the vesting of the outstanding restricted stock units was proportionally decreased. The par value per share and the authorized number of shares of common stock and preferred stock were not adjusted as a result of the reverse stock split. | At a special meeting held on October 14, 2016, XOMA’s stockholders approved the reverse stock split and gave XOMA’s Board of Directors’ discretion to effect the reverse split within a range of ratios. The Board subsequently decided to effect a reverse stock split in a ratio of 1-for-20, effective after market close on October 17, 2016. | |||||||
| Reverse stock split ratio | 0.05 | ||||||||
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