Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 65,402	$ 152,699	$ 125,037
Cost of revenues:
Inventor royalties	4,952	22,730	18,462
Contingent legal fees	16,682	26,474	16,169
Litigation and licensing expenses - patents	18,219	27,858	39,373
Amortization of patents	22,154	34,208	53,067
General and administrative expenses (including non-cash stock compensation expense of $8,885 in 2017, $9,062 in 2016 and $11,048 in 2015)	26,030	32,919	38,176
Other expenses - business development	1,189	3,079	3,391
Impairment of Patent-Related Intangible Assets	2,248	42,340	74,731
Impairment of Goodwill	0	0	30,149
Other	1,200	500	4,141
Total operating costs and expenses	92,674	190,108	277,659
Operating loss	(27,272)	(37,409)	(152,622)
Gain on Conversion of Loan and Accrued Interest	2,671	0	0
Gain on exercise of Primary Warrant	4,616	0	0
Change in fair value of investment	42,239	0	0
Income (Loss) from Equity Method Investments	(220)	0	0
Other Income	1,000	0	0
Investment Income, Interest	1,605	798	(56)
Total other income (expense)	51,911	798	(56)
Income (loss) from operations before provision for income taxes	24,639	(36,611)	(152,678)
Provision for income taxes	(2,955)	(18,188)	(4,800)
Net income (loss) including noncontrolling interests in subsidiaries	21,684	(54,799)	(157,478)
Net (income) loss attributable to noncontrolling interests in subsidiaries	496	732	(2,558)
Net income (loss) attributable to Acacia Research Corporation	22,180	(54,067)	(160,036)
Net Loss Available to Common Stockholders, Basic and Diluted	$ 22,147	$ (54,067)	$ (160,730)
Earnings Per Share, Basic and Diluted	$ 0.44	$ (1.08)	$ (3.25)
Weighted Average Number of Shares Outstanding, Basic	50,495,119	50,075,847	49,505,817
Weighted Average Number of Shares Outstanding, Diluted	50,692,012	50,075,847	49,505,817
Common Stock, Dividends, Per Share, Cash Paid	$ 0.000	$ 0.000	$ 0.500