Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
QUARTERLY FINANCIAL DATA (unaudited) [Abstract]
Revenues	$ 37,497	$ 12,994	$ 40,336	$ 34,210	$ 31,030	$ 37,192	$ 50,076	$ 12,578
Inventor royalties	7,756	116	1,265	9,325	4,358	4,667	10,694	951	$ 18,462	$ 20,670	$ 29,724
Contingent legal fees	3,901	1,972	5,512	4,784	7,296	7,663	7,077	1,527	16,169	23,563	24,784
Litigation and licensing expenses - patents	11,341	10,345	9,012	8,675	8,208	9,592	10,820	8,994	39,373	37,614	39,335
Amortization of patents	13,113	13,688	13,228	13,038	12,796	13,511	15,532	11,906	53,067	53,745	49,039
Marketing, general and administrative expenses (including non-cash stock compensation expense)	(8,572)	(9,442)	(9,587)	(10,575)	(12,044)	(11,636)	(13,181)	(11,693)	(38,176)	(48,554)	(59,229)
Research, consulting and other expenses - business development	860	802	732	997	637	1,208	1,003	992	3,391	3,840	3,251
Impairment of Patent-Related Intangible Assets	74,731	0	0	0	931	0	0	2,566	74,731	3,497	4,619
Impairment of Goodwill	30,149	0	0	0	0	0	0	0	30,149	0	0
Other	250	3,465	0	426	0	1,548	0	0	4,141	1,548	3,506
Total operating costs and expenses	150,673	39,830	39,336	47,820	46,270	49,825	58,307	38,629	277,659	193,031	213,487
Operating loss	(113,176)	(26,836)	1,000	(13,610)	(15,240)	(12,633)	(8,231)	(26,051)	(152,622)	(62,155)	(82,931)
Total other income (expense)	0	(180)	(104)	228	(451)	(57)	(196)	109	(56)	(595)	2,131
Income (loss) from operations before (provision for) benefit from income taxes	(113,176)	(27,016)	896	(13,382)	(15,691)	(12,690)	(8,427)	(25,942)	(152,678)	(62,750)	(80,800)
(Provision) benefit for income taxes	(4,174)	(337)	(119)	(170)	(450)	(145)	(4,689)	1,372	(4,800)	(3,912)	21,958
Net loss including noncontrolling interests in operating subsidiaries	(117,350)	(27,353)	777	(13,552)	(16,141)	(12,835)	(13,116)	(24,570)	(157,478)	(66,662)	(58,842)
Net (income) loss attributable to noncontrolling interests in operating subsidiaries	(1,440)	(43)	4,463	(422)	103	(420)	(167)	(149)	2,558	(633)	(2,408)
Net loss attributable to Acacia Research Corporation	$ (115,910)	$ (27,310)	$ (3,686)	$ (13,130)	$ (16,244)	$ (12,415)	$ (12,949)	$ (24,421)	$ (160,036)	$ (66,029)	$ (56,434)
Earnings Per Share, Basic and Diluted	$ (2.33)	$ (0.55)	$ (0.08)	$ (0.27)	$ (0.34)	$ (0.26)	$ (0.27)	$ (0.51)	$ (3.25)	$ (1.37)	$ (1.18)
Weighted Average Number of Shares Outstanding, Basic and Diluted	49,749,941	49,630,369	49,423,472	49,212,207	48,944,914	48,806,334	48,543,334	48,329,375	49,505,817	48,658,088	48,155,832