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, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Net income (loss) attributable to Acacia Research Corporation	$ (16,244)	$ (12,415)	$ (12,949)	$ (24,421)	$ (33,333)	$ (15,711)	$ (12,503)	$ 5,113	$ (66,029)	$ (56,434)	$ 59,453
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic									0	0	(1,889)
Net Income (Loss) Available to Common Stockholders, Basic									(66,755)	(56,945)	57,564
Undistributed Earnings (Loss) Allocated to Participating Securities, Diluted									0	0	(1,876)
Payments of Dividends									(25,039)	(18,633)	0
Dividends attributable to common stockholders under the two class method									24,313	18,122	0
Net Income (Loss) Available to Common Stockholders, Diluted									$ (66,755)	$ (56,945)	$ 57,577
Weighted-average number of shares outstanding, basic - As Adjusted(1)	48,944,914	48,806,334	48,543,334	48,329,375	48,415,684	48,330,149	48,008,998	47,859,774	48,658,088	48,155,832	47,251,061
Weighted Average Number Diluted Shares Outstanding Adjustment									0	0	333,059
Weighted-average number of shares outstanding, diluted - As Adjusted(1)	48,944,914	48,806,334	48,543,334	48,329,375	48,415,684	48,330,149	48,008,998	48,104,242	48,658,088	48,155,832	47,584,120
Basic income (loss) per common share	$ (0.34)	$ (0.26)	$ (0.27)	$ (0.51)	$ (0.69)	$ (0.33)	$ (0.26)	$ 0.10	$ (1.37)	$ (1.18)	$ 1.22
Diluted income (loss) per common share	$ (0.34)	$ (0.26)	$ (0.27)	$ (0.51)	$ (0.69)	$ (0.33)	$ (0.26)	$ 0.10	$ (1.37)	$ (1.18)	$ 1.21
Anti-dilutive equity-based incentive awards excluded from the computation of diluted income (loss) per share									27,760	27,760	30,812