Unaudited Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 3,815	$ 3,387
Portfolio operations:
Inventor royalties	426	1,353
Contingent legal fees	234	177
Litigation and licensing expenses - patents	1,037	3,801
Amortization of patents	1,043	656
Other portfolio expenses (income)	(234)	650
Total portfolio expenses	2,506	6,637
Net portfolio income (loss)	1,309	(3,250)
General and administrative expenses	4,878	3,655
Operating loss	(3,569)	(6,905)
Other income (expense):
Change in fair value of investment, net (Note 5)	4,108	6,908
Loss on sale of investment (Note 5)	(3,316)	(5,590)
Change in fair value of the Series A and B warrants and embedded derivative	(4,382)	0
Change in fair value of trading securities	(6,117)	675
Gain (loss) on sale of trading securities	112	(43)
Interest income and other	535	871
Total other income (expense)	(9,060)	2,821
Loss before income taxes	(12,629)	(4,084)
Income tax benefit (expense)	1,338	(314)
Net loss including noncontrolling interests in subsidiaries	(11,291)	(4,398)
Net (income) loss attributable to noncontrolling interests in subsidiaries	0	14
Net loss attributable to Acacia Research Corporation	(11,291)	(4,384)
Less: Dividend on Series A redeemable convertible preferred stock	(263)	0
Less: Accretion of Series A redeemable convertible preferred stock	(631)	0
Net loss attributable to common stockholders - basic and diluted	$ (12,185)	$ (4,384)
Basic and diluted net loss per common share	$ (0.24)	$ (0.09)
Weighted average number of shares outstanding - basic and diluted	49,875,396	49,655,881