Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Revenue:
Total revenues	$ 25,691	$ 23,509	$ 49,757	$ 51,514
Operating expenses:
Cost of service revenue	(243)	(115)	(380)	(222)
Research and development	(26,710)	(36,771)	(48,231)	(80,696)
General and administrative	(15,518)	(16,816)	(31,237)	(33,672)
Fair value adjustments	69	0	69	0
Operating loss	(16,711)	(30,193)	(30,022)	(63,076)
Other expense:
Non-operating expense	(12)	7,141	(276)	6,036
Interest expense, net	(13,289)	(31,745)	(26,084)	(61,211)
Net loss	(30,012)	(54,797)	(56,382)	(118,251)
Dividends on Series A-1 convertible preferred stock	(54)	(54)	(108)	(107)
Less: net loss attributable to non-controlling interest	(2,057)	(1,716)	(3,161)	(3,284)
Net loss attributable to Agenus Inc. common stockholders	$ (28,009)	$ (53,135)	$ (53,329)	$ (115,074)
Per common share data:
Basic net loss attributable to Agenus Inc. common stockholders	$ (1)	$ (2.52)	$ (2.03)	$ (5.56)
Diluted net loss attributable to Agenus Inc. common stockholders	$ (1)	$ (2.52)	$ (2.03)	$ (5.56)
Weighted average number of Agenus Inc. common shares outstanding:
Basic	28,117	21,062	26,303	20,715
Diluted	28,117	21,062	26,303	20,715
Other comprehensive loss:
Foreign currency translation loss	$ (36)	$ 70	$ (106)	$ (46)
Other comprehensive loss	(36)	70	(106)	(46)
Comprehensive loss	(28,045)	(53,065)	(53,435)	(115,120)
Research and Development Revenue [Member]
Revenue:
Total revenues	334	267	334	267
Service Revenue [Member]
Revenue:
Total revenues	526	660	1,036	898
Non-Cash Royalty Revenue Related to the Sale of Future Royalties [Member]
Revenue:
Total revenues	$ 24,831	$ 22,582	$ 48,387	$ 50,349