UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement [Abstract]
Revenues	$ 19,466	$ 1,711	$ 25,399	$ 10,558
Portfolio operations:
Inventor royalties	5,772	776	6,843	4,752
Contingent legal fees	6,609	35	6,855	587
Litigation and licensing expenses - patents	1,001	987	3,497	6,643
Amortization of patents	1,174	863	3,522	2,337
Other portfolio expenses (income)	0	(475)	(308)	175
Total portfolio operations	14,556	2,186	20,409	14,494
Net portfolio income (loss)	4,910	(475)	4,990	(3,936)
General and administrative expenses(1)	7,692	4,630	18,089	12,048
Operating loss	(2,782)	(5,105)	(13,099)	(15,984)
Other income (expense):
Change in fair value of investment, net (Note 5)	(3,081)	(4,266)	3,704	9,622
Loss on sale of investment (Note 5)	0	(915)	(2,762)	(8,147)
Impairment of other investment	0	0	0	(8,195)
Gain on disposal of other investment	0	2,000	0	2,000
Change in fair value of the Series A and B warrants and embedded derivatives	20,672	0	(46,612)	0
Change in fair value of equity securities derivative and forward contract	(64,011)	0	17,542	0
Gain on sale of prepaid investment and derivative	2,845	0	2,845	0
Change in fair value of trading securities and equity securities - private	84,499	(482)	81,907	132
Gain (loss) on sale of trading securities	2,737	238	(4,272)	226
Loss on foreign currency exchange	(48)	(106)	(4,938)	(106)
Interest expense on Senior Secured Notes	(2,410)	0	(3,178)	0
Interest income and other	10	1,028	811	3,012
Total other income (expense)	41,213	(2,503)	45,047	(1,456)
Income (loss) before income taxes	38,431	(7,608)	31,948	(17,440)
Income tax benefit (expense)	(83)	0	1,257	(323)
Net income (loss) including noncontrolling interests in subsidiaries	38,348	(7,608)	33,205	(17,763)
Net loss attributable to noncontrolling interests in subsidiaries	0	0	0	14
Net income (loss) attributable to Acacia Research Corporation	38,348	(7,608)	33,205	(17,749)
Net income (loss) attributable to common stockholders - basic	$ 30,529	$ (7,608)	$ 24,838	$ (17,749)
Basic net income (loss) per common share	$ 0.63	$ (0.15)	$ 0.51	$ (0.36)
Weighted average number of shares outstanding - basic	48,467,885	49,828,361	48,949,706	49,727,385
Net income (loss) attributable to common stockholders - diluted	$ 29,204	$ (7,608)	$ 21,380	$ (17,749)
Diluted net income (loss) per common share	$ 0.32	$ (0.15)	$ 0.36	$ (0.36)
Weighted average number of shares outstanding - diluted	90,624,702	49,828,361	60,153,773	49,727,385