Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Collaboration and other revenue		$ 250	$ 429	$ 5,200
Operating expenses:
Research and development expense (includes related party amounts of $0, $0, and $1,885, respectively)		58,274	19,933	25,919
General and administrative expense (includes related party amounts of $0, $0, and $15, respectively)		38,416	10,595	7,549
Total operating expenses		96,690	30,528	33,468
Loss from operations		(96,440)	(30,099)	(28,268)
Other income (expense):
Interest income		350	100	128
Interest expense (includes related party amounts of $0, $147 and $52, respectively)		(3)	(1,389)	(1,630)
Change in fair value of derivative liability		0	(1,581)	(63)
Gain (loss) on extinguishment of long-term debt		690	(2,883)	0
Other income (expense)		1	(1)	(22)
Total other income (expense)		1,038	(5,754)	(1,587)
Consolidated net loss and comprehensive loss		(95,402)	(35,853)	(29,855)
Net loss attributable to noncontrolling interests		0	0	61
Net loss attributable to BioAtla, Inc./BioAtla LLC		$ (95,402)	$ (35,853)	(29,794)
Net loss allocable to Class C preferred unit holders				9,089
Class C preferred return				(8,026)
Net loss attributable to Class A unit holders				$ (28,731)
Net loss per common share, basic and diluted	[1]	$ (2.76)	$ (3.19)
Weighted-average shares of common stock outstanding, basic and diluted	[1]	34,561,245	8,428,153
Class A units
Other income (expense):
Net loss per common share, basic and diluted				$ (0.53)
Weighted-average shares of common stock outstanding, basic and diluted				54,600,000

[1] The net loss attributable to common stockholders and related per share amounts for the year ended December 31, 2020 are based on the period from July 10, 2020 to December 31, 2020, the period where the Company had outstanding common stock (see Note 1).