Consolidated Balance Sheets Statement (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and Cash Equivalents	$ 315,498	$ 314,733
Short-term investments	134,185	6,597
Accounts receivable	1,280	2,915
Prepaid expenses and other current assets	2,431	803
Total current assets	453,394	325,048
Property and equipment, net of accumulated depreciation	212	220
Patents, net of accumulated amortization	171,262	25,188
Goodwill	36,202	0
Investments - noncurrent	1,956	1,956
Other assets	465	465
Total assets	663,491	352,877
Current Liabilities [Abstract]
Accounts payable and accrued expenses	8,407	6,625
Royalties and contingent legal fees payable	14,095	23,508
Total current liabilities	22,502	30,133
Deferred Tax Liabilities, Noncurrent	32,363	0
Other liabilities	642	632
Total liabilities	55,507	30,765
Commitments and contingencies (Note 5)
Stockholders' Equity [Abstract]
Preferred stock, par value $0.001 per share; 10,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, par value $0.001 per share; 100,000,000 shares authorized; 42,873,001 and 36,029,068 shares issued and outstanding as of September 30, 2011 and December 31, 2010, respectively	50	43
Additional paid-in capital	618,683	386,821
Accumulated comprehensive loss	600	(1,830)
Accumulated deficit	(15,157)	(65,085)
Total Acacia Research Corporation stockholders' equity	604,176	319,949
Noncontrolling interests in operating subsidiaries	3,808	2,163
Total stockholders' equity	607,984	322,112
Total liabilities and stockholders' equity	$ 663,491	$ 352,877