Acquisitions Pro Forma Information (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Business Acquisition [Line Items]
Revenues	$ 99,040	$ 61,130
Total operating costs and expenses	35,334	44,485
Operating income	63,706	16,645
Total other incomes	56	29
Income from operations before provision for income taxes	63,762	16,674
Provision for income taxes	(14,747)	(7,148)
Net income including noncontrolling interests in operating subsidiaries	49,015	9,526
Net (income) loss attributable to noncontrolling interests in operating subsidiaries	275	(1,203)
Net income attributable to Acacia Research Corporation	$ 49,290	$ 8,323
Pro forma income per common share attributable to Acacia Research Corporation: Basic earnings per share	$ 1.11	$ 0.24
Pro forma income per common share attributable to Acacia Research Corporation: Diluted earnings per share	$ 1.08	$ 0.23
Weighted average number of shares outstanding, basic	44,367,499	35,182,811
Weighted average number of shares outstanding, diluted	45,771,228	36,448,005