Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Related Party Transaction [Line Items]
Research and development expense	$ 16,198	$ 30,960	$ 35,050	$ 52,657
Due to related party	100		$ 100
Himalaya Therapeutics SEZC
Related Party Transaction [Line Items]
Description of agreement with related party			In January 2024, the Company entered into an amended Clinical Trial Services Agreement with Himalaya Therapeutics SEZC (as so amended, the “Clinical Trial Services Agreement”). Under the Clinical Trial Services Agreement, BioAtla will pay Himalaya Therapeutics SEZC 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. For the three and six months ended June 30, 2024, the Company recognized $0.1 million and $0.3 million, respectively, in research and development expense related to the Clinical Trial Services Agreement, compared to $0 and $0.1 million for the three and six months ended June 30, 2023, respectively. As of June 30, 2024, the Company had $0.1 million due to Himalaya Therapeutics SEZC, related to the Clinical Trial Services Agreement.
Research and development expense	$ 100	$ 0	$ 300	$ 100