Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Apexigen, Inc.	Pfizer License Agreement	Common Stock	Common Stock Apexigen, Inc.	Common Stock Pfizer License Agreement	Additional Paid-in Capital	Additional Paid-in Capital Apexigen, Inc.	Additional Paid-in Capital Pfizer License Agreement	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance at Dec. 31, 2022	$ 160,824			$ 34			$ 373,225				$ (212,435)
Beginning Balance, Shares at Dec. 31, 2022				34,958,730
Issuance of common stock		$ 10,732	$ 5,000		$ 4	$ 2		$ 10,728	$ 4,998
Issuance of common stock (Shares)					4,344,435	1,811,594
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7) (Shares)				1,001,208
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7)	6,122			$ 1			6,121
Issuance of common stock under employee stock purchase plan ("ESPP")	105						105
Issuance of common stock under employee stock purchase plan ("ESPP") (Shares)				60,567
Issuance of restricted common stock, net of tax withholdings	(390)			$ 3			(393)
Issuance of restricted common stock, net of tax withholdings, (Shares)				2,040,288
Shares issued pursuant to the ATM program, net of commission (shares)				1,001,208
Stock options exercised	120						120
Stock options exercised (Shares)				77,270
Stock-based compensation	13,731						13,731
Net unrealized (loss) gain on marketable debt securities	(105)									$ (105)
Net Income (Loss)	(58,193)										(58,193)
Ending balance at Sep. 30, 2023	137,946			$ 44			408,635			(105)	(270,628)
Ending balance (in shares) at Sep. 30, 2023				44,294,092
Beginning balance at Jun. 30, 2023	145,275			$ 39			392,900			(85)	(247,579)
Beginning Balance, Shares at Jun. 30, 2023				39,376,941
Issuance of common stock		$ 10,732			$ 4			$ 10,728
Issuance of common stock (Shares)					4,344,435
Vesting of restricted common stock, net of tax withholdings (Shares)				455,375
Vesting of restricted common stock, net of tax withholdings	(393)			$ 1			(394)
Issuance of common stock under employee stock purchase plan ("ESPP")	105						105
Issuance of common stock under employee stock purchase plan ("ESPP") (Shares)				60,567
Shares issued pursuant to the ATM program, net of commission (shares)				0
Stock options exercised	117						117
Stock options exercised (Shares)				56,774
Stock-based compensation	5,179						5,179
Net unrealized (loss) gain on marketable debt securities	(20)									(20)
Net Income (Loss)	(23,049)										(23,049)
Ending balance at Sep. 30, 2023	137,946			$ 44			408,635			(105)	(270,628)
Ending balance (in shares) at Sep. 30, 2023				44,294,092
Beginning balance at Dec. 31, 2023	125,704			$ 45			411,821			63	(286,225)
Beginning Balance, Shares at Dec. 31, 2023				44,754,853
Issuance of common stock in private placement, net of offering costs (See Note 7) (Shares)				8,849,371
Issuance of common stock in private placement, net of offering costs (See Note 7)	39,172			$ 9			39,163
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7) (Shares)				4,050,000
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7)	12,174			$ 4			12,170
Issuance of pre-funded warrants in private placement, net of offering costs (See Note 8)	7,700						7,700
Issuance of common stock under employee stock purchase plan ("ESPP")	177						177
Issuance of common stock under employee stock purchase plan ("ESPP") (Shares)				86,481
Issuance of restricted common stock, net of tax withholdings	(240)			$ 1			(241)
Issuance of restricted common stock, net of tax withholdings, (Shares)				1,587,161
Shares issued pursuant to the ATM program, net of commission (shares)				4,050,000
Stock options exercised	$ 293						293
Stock options exercised (Shares)	122,132			122,132
Stock-based compensation	$ 10,172						10,172
Net unrealized (loss) gain on marketable debt securities	288									288
Net Income (Loss)	(41,760)										(41,760)
Ending balance at Sep. 30, 2024	153,680			$ 59			481,255			351	(327,985)
Ending balance (in shares) at Sep. 30, 2024				59,449,998
Beginning balance at Jun. 30, 2024	169,794			$ 59			476,619			(102)	(306,782)
Beginning Balance, Shares at Jun. 30, 2024				58,914,712
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7) (Shares)				450,000
Issuance of common stock pursuant to at-the-market program, net of offering costs (See Note 7)	1,584						1,584
Issuance of common stock under employee stock purchase plan ("ESPP")	72						72
Issuance of common stock under employee stock purchase plan ("ESPP") (Shares)				26,599
Issuance of restricted common stock, net of tax withholdings	(1)						(1)
Issuance of restricted common stock, net of tax withholdings, (Shares)				58,687
Shares issued pursuant to the ATM program, net of commission (shares)				450,000
Stock-based compensation	2,981						2,981
Net unrealized (loss) gain on marketable debt securities	453									453
Net Income (Loss)	(21,203)										(21,203)
Ending balance at Sep. 30, 2024	$ 153,680			$ 59			$ 481,255			$ 351	$ (327,985)
Ending balance (in shares) at Sep. 30, 2024				59,449,998