Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 61,808,000	$ 53,054,000
Inventories	0	55,000
Accounts Receivable	16,293,000	938,000
Prepaid expenses	7,420,000	19,265,000
Other current assets	1,015,000	1,496,000
Total current assets	86,536,000	74,808,000
Property, plant and equipment, net of accumulated amortization and depreciation of $42,861 and $38,068 at December 31, 2019 and 2018, respectively	26,326,000	25,116,000
Operating lease right-of-use assets	7,364,000
Goodwill	23,188,000	22,925,000
Acquired intangible assets, net of accumulated amortization of $9,431 and $7,472 at December 31, 2019 and 2018, respectively	10,504,000	12,338,000
Other long-term assets	1,417,000	1,214,000
Total assets	155,335,000	136,401,000
LIABILITIES, CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ DEFICIT
Current portion, long-term debt	646,000	146,000
Current portion, liability related to sale of future royalties and milestones	45,961,000	27,443,000
Current portion, deferred revenue	29,174,000	1,814,000
Current portion, operating lease liabilities	1,347,000
Accounts payable	13,564,000	13,624,000
Accrued liabilities	31,332,000	24,551,000
Other current liabilities	185,000	484,000
Total current liabilities	122,209,000	68,062,000
Long-term debt	13,380,000	13,212,000
Liability related to sale of future royalties and milestones, net of current portion	175,408,000	182,817,000
Deferred revenue, net of current portion	27,705,000	1,165,000
Operating lease liabilities, net of current portion	8,020,000
Contingent purchase price consideration	8,843,000	3,038,000
Other long-term liabilities	4,190,000	2,773,000
Commitments and contingencies (Note 19)
STOCKHOLDERS’ DEFICIT
Common stock, par value $0.01 per share; 400,000,000 shares and 240,000,000 shares authorized; 137,818,068 shares and 119,996,331 shares issued at December 31, 2019 and 2018, respectively	1,378,000	1,200,000
Additional paid-in capital	1,059,583,000	1,005,183,000
Accumulated other comprehensive loss	(1,324,000)	(1,539,000)
Accumulated deficit	(1,284,993,000)	(1,177,311,000)
Total stockholders’ deficit attributable to Agenus Inc.	(225,356,000)	(172,467,000)
Non-controlling interest	(5,981,000)	(2,078,000)
Total stockholders’ deficit	(231,337,000)	(174,545,000)
Total liabilities, convertible preferred stock and stockholders’ deficit	155,335,000	136,401,000
Series C-1 Convertible Preferred Stock [Member]
CONVERTIBLE PREFERRED STOCK
Series C-1 convertible preferred stock; 12,459 shares and 18,459 shares designated, issued, and outstanding at December 31, 2019 and 2018, respectively	26,917,000	39,879,000
Series A-1 convertible preferred stock [Member]
STOCKHOLDERS’ DEFICIT
Series A-1 convertible preferred stock; 31,620 shares designated, issued, and outstanding at December 31, 2019 and 2018; liquidation value of $33,040 and $32,832 at December 31, 2019, and 2018, respectively	0	0
Total stockholders’ deficit	$ 0	$ 0