Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Apexigen, Inc.	Pfizer License Agreement	ESPP	Common Stock	Common Stock Apexigen, Inc.	Common Stock Pfizer License Agreement	Common Stock ESPP	Additional Paid-in Capital	Additional Paid-in Capital Apexigen, Inc.	Additional Paid-in Capital Pfizer License Agreement	Additional Paid-in Capital ESPP	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance at Dec. 31, 2021	$ 261,313				$ 32				$ 352,999					$ (91,718)
Beginning Balance, Shares at Dec. 31, 2021					32,222,881
Issuance of common stock	4,281				$ 2				4,279
Issuance of common stock (Shares)					2,229,654
Stock options exercised	183								183
Stock options exercised (Shares)					73,841
Issuance of restricted common stock, net of tax withholdings (Shares)					432,354
Stock-based compensation	15,764								15,764
Net loss	(120,717)													(120,717)
Ending balance at Dec. 31, 2022	160,824				$ 34				373,225					(212,435)
Ending balance (in shares) at Dec. 31, 2022					34,958,730
Issuance of common stock		$ 10,732	$ 5,000	$ 132		$ 4	$ 2			$ 10,728	$ 4,998	$ 132
Issuance of common stock (Shares)						4,344,435	1,811,594	79,350
Shares issued pursuant to at-the-market ("ATM") program, net of commission	6,122				$ 1				6,121
Shares issued pursuant to at-the-market ("ATM") program, net of commission (shares)					1,001,208
Stock options exercised	$ 120								120
Stock options exercised (Shares)	83,235				83,235
Issuance of restricted common stock, net of tax withholdings	$ (445)				$ 4				(449)
Issuance of restricted common stock, net of tax withholdings (Shares)					2,476,301
Stock-based compensation	16,946								16,946
Net unrealized gain on marketable debt securities	63												$ 63
Net loss	(73,790)													(73,790)
Ending balance at Dec. 31, 2023	$ 125,704				$ 45				$ 411,821				$ 63	$ (286,225)
Ending balance (in shares) at Dec. 31, 2023					44,754,853