Acquisitions Pro Forma Information (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Business Acquisition [Line Items]
Revenues	$ 50,484	$ 39,746	$ 149,524	$ 100,876
Total operating costs and expenses	40,711	41,893	76,045	86,870
Operating income (loss)	9,773	(2,147)	73,479	14,006
Interest and investment income	102	24	158	53
Income (loss) from operations before provision for income taxes	9,875	(2,123)	73,637	14,059
Provision for income taxes	(3,494)	(306)	(18,241)	(7,454)
Net income (loss) including noncontrolling interests in operating subsidiaries	6,381	(2,429)	55,396	6,605
Net (income) loss attributable to noncontrolling interests in operating subsidiaries	(60)	300	215	(903)
Net income (loss) attributable to Acacia Research Corporation	$ 6,321	$ (2,129)	$ 55,611	$ 5,702
Pro forma income (loss) per common share attributable to Acacia Research Corporation: Basic earnings (loss) per share	$ 0.13	$ (0.05)	$ 1.20	$ 0.15
Pro forma income (loss) per common share attributable to Acacia Research Corporation: Diluted earnings (loss) per share	$ 0.13	$ (0.05)	$ 1.18	$ 0.14
Weighted average number of shares outstanding, basic	47,944,193	40,994,082	46,155,846	38,104,500
Weighted average number of shares outstanding, diluted	48,938,766	42,453,782	47,208,105	39,477,616