Related Party Transactions - Additional Information (Details) - USD ($)		12 Months Ended
	Jul. 07, 2020	Dec. 31, 2024	Dec. 31, 2023	Jan. 01, 2020
Related Party Transaction [Line Items]
Research and development expense		$ 63,095,000	$ 103,731,000
Description Of Agreement With Related Party		In September 2024, the Company entered into a Global Transaction Agreement (the “Himalaya Agreement”) with Himalaya. BioAtla and Himalaya had previously entered into an Amended and Restated Exclusive Rights Agreement (the “Amended Rights Agreement”) in January of 2020. Pursuant to the Amended Rights Agreement, Himalaya controls rights to develop, manufacture and commercialize certain assets, including BA3362 which was licensed to Context (see Note 7), in certain territories as further specified in the Amended Rights Agreement. Pursuant to the Himalaya Agreement, Himalaya consented to BioAtla’s execution and performance of the Agreement, and granted to BioAtla an exclusive, worldwide, sublicensable license for those impacted products and intellectual property. Further, as set forth in the Amended Rights Agreement and further clarified in the Himalaya Agreement, BioAtla agreed to pay, subject to any applicable tax withholdings, to Himalaya (i) a mid-teens percentage of all upfront payments and development milestones received by BioAtla from Context under the Context License Agreement; and (ii) a specified percentage of any and all sales milestones and/or royalties based upon Net Sales (as defined in the Context License Agreement) in the People’s Republic of China and the Special Administrative Regions of Hong Kong, Macao and Taiwan that BioAtla receives from Context under the Context License Agreement.
Inversagen LLC
Related Party Transaction [Line Items]
Royalty Expense	$ 0
Options grants related to royalty payment, Period		10 years
Assets or liabilities associated with related party variable interest		$ 0	0
Himalaya Therapeutics SEZC
Related Party Transaction [Line Items]
Research and development expense		2,200,000	100,000
Royalty Expense		$ 0
Description Of Agreement With Related Party		In January 2024, the Company entered into an amended Clinical Trial Services Agreement (as so amended, the “Clinical Trial Services Agreement”) with Himalaya Therapeutics SEZC (“Himalaya”). Under the Clinical Trial Services Agreement, BioAtla will pay Himalaya for the full-time use of two of its personnel and provide services related to the initiation of clinical trials for evalstotug in China for a period of 12 months. All payments have been made under this agreement as of December 31, 2024.
Assets or liabilities associated with related party variable interest		$ 0
Bio Atla Holdings LLC
Related Party Transaction [Line Items]
Assets or liabilities associated with related party variable interest		$ 0	$ 0
Options grants related to royalty payments, Period	10 years
Share of Royalties under Royalty Sharing Agreement				50.00%