Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenues	$ 5,460	$ 6,485	$ 8,847	$ 68,578
Portfolio operations:
Inventor royalties	2,623	1,241	3,976	22,985
Contingent legal fees	375	1,037	552	16,796
Patent acquisition expenses	0	0	0	4,000
Litigation and licensing expenses - patents	1,855	2,639	5,656	5,628
Amortization of patents	818	5,278	1,474	10,608
Other portfolio expenses	0	0	650	0
Total portfolio expenses	5,671	10,195	12,308	60,017
Net portfolio income (loss)	(211)	(3,710)	(3,461)	8,561
General and administrative expenses(1)	3,810	6,916	7,505	10,217
Impairment of patent-related intangible assets	0	28,210	0	28,210
Operating loss	(4,021)	(38,836)	(10,966)	(29,866)
Other income (expense):
Change in fair value of investment, net (Note 5)	6,980	11,347	13,888	(29,750)
Loss on sale of investment (Note 5)	(1,642)	0	(7,232)	0
Impairment of other investment	(8,195)	(1,000)	(8,195)	(1,000)
Interest income and other	1,130	268	2,673	475
Total other income (expense)	(1,727)	10,615	1,134	(30,275)
Loss before provision for income taxes	(5,748)	(28,221)	(9,832)	(60,141)
Provision for income taxes	(9)	(285)	(323)	(476)
Net loss including noncontrolling interests in subsidiaries	(5,757)	(28,506)	(10,155)	(60,617)
Net loss attributable to noncontrolling interests in subsidiaries	0	79	14	152
Net loss attributable to Acacia Research Corporation	(5,757)	(28,427)	(10,141)	(60,465)
Net loss attributable to common stockholders - basic and diluted	$ (5,757)	$ (28,427)	$ (10,141)	$ (60,465)
Basic and diluted net loss per common share	$ (0.12)	$ (0.57)	$ (0.20)	$ (1.20)
Weighted average number of shares outstanding - basic and diluted	49,696,016	50,061,812	49,676,059	50,345,808
General and administrative expenses	$ 3,349	$ 5,710	$ 7,052	$ 10,035
Non-cash stock compensation expense - G&A	461	521	453	1,225
Non-cash stock compensation expense - Profits Interests (Note 9)	0	685	0	(1,043)
Total general and administrative expenses	$ 3,810	$ 6,916	$ 7,505	$ 10,217