Quarterly Financial Data (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
QUARTERLY FINANCIAL DATA (unaudited) [Abstract]
Revenues	$ 15,065	$ 15,520	$ 23,110	$ 76,861	$ 66,264	$ 34,939	$ 50,484	$ 99,040
Inventor royalties	3,280	2,353	5,610	18,481	3,829	5,032	9,573	7,594	29,724	26,028	43,727
Contingent legal fees	3,181	2,547	4,024	15,032	5,463	8,833	6,607	3,748	24,784	24,651	40,281
Litigation and licensing expenses - patents	8,899	10,870	9,918	9,648	6,969	5,973	5,268	3,381	39,335	21,591	13,005
Amortization of patents	16,735	12,615	12,578	11,730	18,088	10,412	5,393	5,126	53,658	39,019	9,745
Marketing, general and administrative expenses (including non-cash stock compensation expense)	(13,988)	(18,222)	(13,175)	(13,844)	(16,535)	(11,914)	(11,903)	(13,731)	(59,229)	(54,083)	(35,693)
Research, consulting and other expenses - business development	742	743	735	1,031	721	1,139	1,967	1,116	3,251	4,943	4,338
Other	0	3,506	0	0	0	0	0	0	3,506	0	0
Total operating costs and expenses	46,825	50,856	46,040	69,766	51,605	43,303	40,711	34,696	213,487	170,315	141,999
Operating income (loss)	(31,760)	(35,336)	(22,930)	7,095	14,659	(8,364)	9,773	64,344	(82,931)	80,412	30,257
Total other income (expense)	161	280	400	1,290	820	(41)	102	56	2,131	937	96
Income (loss) from operations before benefit from (provision for) income taxes	(31,599)	(35,056)	(22,530)	8,385	15,479	(8,405)	9,875	64,400	(80,800)	81,349	30,353
(Provision) benefit for income taxes	(3,390)	19,570	9,050	(3,272)	(5,757)	1,938	(3,494)	(14,747)	21,958	(22,060)	(8,708)
Net income (loss) including noncontrolling interests in operating subsidiaries	(34,989)	(15,486)	(13,480)	5,113	9,722	(6,467)	6,381	49,653	(58,842)	59,289	21,645
Net (income) loss attributable to noncontrolling interests	1,656	(225)	977	0	101	(152)	(60)	275	2,408	164	(539)
Net Income (Loss) Attributable to Acacia Research Corporation	$ (33,333)	$ (15,711)	$ (12,503)	$ 5,113	$ 9,823	$ (6,619)	$ 6,321	$ 49,928	$ (56,434)	$ 59,453	$ 21,106
Basic income (loss) per share - As Adjusted(1)	$ (0.69)	$ (0.33)	$ (0.26)	$ 0.10	$ 0.20	$ (0.14)	$ 0.13	$ 1.08	$ (1.18)	$ 1.22	$ 0.51
Diluted income (loss) per share - As Adjusted(1)	$ (0.69)	$ (0.33)	$ (0.26)	$ 0.10	$ 0.20	$ (0.14)	$ 0.13	$ 1.08	$ (1.18)	$ 1.21	$ 0.50
Weighted-average number of shares outstanding, basic - As Adjusted(1)	48,415,684	48,330,149	48,008,998	47,859,774	48,335,865	48,332,878	47,944,193	44,367,499	48,155,832	47,251,061	39,743,433
Weighted-average number of shares outstanding, diluted - As Adjusted(1)	48,415,684	48,330,149	48,008,998	48,104,242	48,607,141	48,332,878	48,294,782	44,764,064	48,155,832	47,584,120	40,150,600
Earnings (loss) per share, basic, as previously reported			$ (0.26)	$ 0.11	$ 0.20	$ (0.14)	$ 0.13	$ 1.13
Earnings (loss) per share, diluted as previously reported			$ (0.26)	$ 0.11	$ 0.20	$ (0.14)	$ 0.13	$ 1.09
Weighted average number of shares, basic, as previously reported			48,008,998	47,859,774	48,335,865	48,332,878	47,944,193	44,367,499
Weighted average number of shares, diluted, as previously reported			48,008,998	48,354,444	48,797,304	48,332,878	48,938,766	45,771,228