Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 1,711	$ 13,725	$ 10,558	$ 82,303
Portfolio operations:
Inventor royalties	776	1,181	4,752	24,166
Contingent legal fees	35	2,949	587	19,745
Patent acquisition expenses	0	0	0	4,000
Litigation and licensing expenses - patents	987	1,549	6,643	7,177
Amortization of patents	863	4,952	2,337	15,560
Other portfolio expenses	(475)	2,202	175	2,202
Total portfolio expenses	2,186	12,833	14,494	72,850
Net portfolio income (loss)	(475)	892	(3,936)	9,453
General and administrative expenses	4,670	5,855	12,175	16,072
Impairment of patent-related intangible assets	0	0	0	28,210
Operating loss	(5,145)	(4,963)	(16,111)	(34,829)
Other income (expense):
Change in fair value of investment, net (Note 5)	(4,266)	(24,211)	9,622	(53,961)
Loss on sale of investment (Note 5)	(915)	(3,705)	(8,147)	(3,705)
Impairment of other investment	0	0	(8,195)	(1,000)
Gain on disposal of other investment	2,000	0	2,000	0
Interest income and other	718	321	3,391	796
Total other expense	(2,463)	(27,595)	(1,329)	(57,870)
Loss before provision for income taxes	(7,608)	(32,558)	(17,440)	(92,699)
Provision for income taxes	0	(306)	(323)	(782)
Net loss including noncontrolling interests in subsidiaries	(7,608)	(32,864)	(17,763)	(93,481)
Net (income) loss attributable to noncontrolling interests in subsidiaries	0	(331)	14	(179)
Net loss attributable to Acacia Research Corporation	(7,608)	(33,195)	(17,749)	(93,660)
Net loss attributable to common stockholders - basic and diluted	$ (7,608)	$ (33,195)	$ (17,749)	$ (93,660)
Basic and diluted net loss per common share	$ (0.15)	$ (0.67)	$ (0.36)	$ (1.87)
Weighted average number of shares outstanding - basic and diluted	49,828,361	49,557,748	49,727,385	50,080,234