UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF SERIES A REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Series A Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Beginning balance, value at Dec. 31, 2018		$ 50	$ (39,272)	$ 651,156	$ (422,541)	$ 1,847	$ 191,240
Beginning balance, shares at Dec. 31, 2018		49,639,319
Net income (loss) attributable to Acacia Research Corporation					(17,749)		(17,749)
Stock options exercised				79			79
Stock options exercised, shares		25,136
Compensation expense for share-based awards, net of forfeitures				753			753
Compensation expense for share-based awards, net of forfeitures, shares		678,850
Net income attributable to noncontrolling interests in subsidiaries						(14)	(14)
Ending balance, value at Sep. 30, 2019		$ 50	(39,272)	651,988	(440,290)	1,833	174,309
Ending balance, shares at Sep. 30, 2019		50,343,305
Beginning balance, value at Jun. 30, 2019		$ 50	(39,272)	651,688	(432,682)	1,833	181,617
Beginning balance, shares at Jun. 30, 2019		50,132,871
Net income (loss) attributable to Acacia Research Corporation					(7,608)		(7,608)
Compensation expense for share-based awards, net of forfeitures				300			300
Compensation expense for share-based awards, net of forfeitures, shares		210,434
Net income attributable to noncontrolling interests in subsidiaries							(0)
Ending balance, value at Sep. 30, 2019		$ 50	(39,272)	651,988	(440,290)	1,833	174,309
Ending balance, shares at Sep. 30, 2019		50,343,305
Beginning balance, value at Dec. 31, 2019	$ 8,089	$ 50	(39,272)	652,003	(439,656)	1,833	174,958
Beginning balance, shares at Dec. 31, 2019	350,000	50,370,987
Net income (loss) attributable to Acacia Research Corporation					33,205		33,205
Accretion of Series A Redeemable Convertible Preferred Stock to redemption value	2,045			(2,045)			(2,045)
Stock options exercised				48			48
Stock options exercised, shares
Dividend on Series A Redeemable Convertible Preferred Stock				(1,119)			(1,119)
Compensation expense for share-based awards, net of forfeitures				1,243			1,243
Compensation expense for share-based awards, net of forfeitures, shares		593,003
Repurchase of common stock		$ (1)	(3,998)				(3,999)
Repurchase of common stock, shares		(1,684,537)
Net income attributable to noncontrolling interests in subsidiaries							(0)
Ending balance, value at Sep. 30, 2020	$ 10,134	$ 49	(43,270)	650,130	(406,451)	1,833	202,291
Ending balance, shares at Sep. 30, 2020	350,000	49,279,453
Beginning balance, value at Jun. 30, 2020	$ 9,400	$ 49	(43,270)	650,843	(444,799)	1,833	164,656
Beginning balance, shares at Jun. 30, 2020	350,000	49,306,137
Net income (loss) attributable to Acacia Research Corporation					38,348		38,348
Accretion of Series A Redeemable Convertible Preferred Stock to redemption value	734			(734)			(734)
Dividend on Series A Redeemable Convertible Preferred Stock				(467)			(467)
Compensation expense for share-based awards, net of forfeitures				488			488
Compensation expense for share-based awards, net of forfeitures, shares		(26,684)
Net income attributable to noncontrolling interests in subsidiaries							(0)
Ending balance, value at Sep. 30, 2020	$ 10,134	$ 49	$ (43,270)	$ 650,130	$ (406,451)	$ 1,833	$ 202,291
Ending balance, shares at Sep. 30, 2020	350,000	49,279,453