Summary of Significant Accounting Policies Earnings per share (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
Accounting Policies [Abstract]
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
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted									0	(1,876)	(833)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									0	(1,889)	(841)
Payments of Dividends									18,633	0	0
Dividends attributable to common stockholders under the two class method									18,122	0	0
Net Income (Loss) Available to Common Stockholders, Basic									(56,945)	57,564	20,265
Net Income (Loss) Available to Common Stockholders, Diluted									$ (56,945)	$ 57,577	$ 20,273
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 Diluted Shares Outstanding Adjustment									0	333,059	407,167
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
Basic income (loss) per common share	$ (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 common share	$ (0.69)	$ (0.33)	$ (0.26)	$ 0.10	$ 0.20	$ (0.14)	$ 0.13	$ 1.08	$ (1.18)	$ 1.21	$ 0.50
Anti-dilutive equity-based incentive awards excluded from the computation of diluted income (loss) per share									27,760	30,812	7,760