Condensed Consolidated Statement of Stockholders' Equity Statement - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Noncontrolling Interests in Operating Subsidiaries [Member]
Common Shares, outstanding at period start (in shares) at Dec. 31, 2017		50,639,926
Balance at period start at Dec. 31, 2017	$ 295,659	$ 51	$ (34,640)	$ 648,996	$ (88)	$ (320,018)	$ 1,358
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to Acacia Research Corporation	(32,038)					(32,038)
Stock options exercised (in shares)		10,000
Stock options exercised	$ 31			$ 31
Compensation expense for share-based awards, net of forfeitures	704,000			704,000
Repurchase of restricted common stock (in shares)		(2,044)
Repurchase of restricted common stock	$ (7)			$ (7)
Net income attributable to noncontrolling interests in subsidiaries	(73)						(73)
Unrealized gain on foreign currency translation	(17)				(17)
Unrealized loss on short-term investments	(20)				(20)
Common shares, outstanding at period end (in shares) at Mar. 31, 2018		50,647,882
Balance at period end at Mar. 31, 2018	$ 267,053	$ 51	(34,640)	649,724	(125)	(349,550)	1,593
Common Shares, outstanding at period start (in shares) at Dec. 31, 2018	49,639,319	49,639,319
Balance at period start at Dec. 31, 2018	$ 191,240	$ 50	(39,272)	651,156	0	(422,541)	1,847
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss attributable to Acacia Research Corporation	(4,384)					(4,384)
Stock options exercised (in shares)		16,748
Stock options exercised	(8)			(8)
Net income attributable to noncontrolling interests in subsidiaries	$ (14)						(14)
Common shares, outstanding at period end (in shares) at Mar. 31, 2019	49,656,067	49,656,067
Balance at period end at Mar. 31, 2019	$ 186,834	$ 50	$ (39,272)	$ 651,148	$ 0	$ (426,925)	$ 1,833