Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 109,562	$ 136,604
Short-term investments - debt securities	30,837	0
Short-term investments - equity securities	3,011	0
Accounts receivable	10,572	153
Prepaid expenses and other current assets	3,121	2,938
Total current assets	157,103	139,695
Investments at fair value	36,648	104,754
Investment - other	8,195	2,195
Patents, net	18,147	61,917
Other assets	183	207
Total assets	220,276	308,768
Current liabilities:
Accounts payable and accrued expenses	9,067	7,956
Royalties and contingent legal fees payable	7,193	1,601
Total current liabilities	16,260	9,557
Other liabilities	1,874	3,552
Total liabilities	18,134	13,109
Commitments and contingencies (Note 6)
Stockholders' equity:
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; 49,639,319 and 50,639,926 shares issued and outstanding as of September 30, 2018 and December 31, 2017, respectively	50	51
Treasury stock, at cost, 2,919,828 and 1,729,408 shares as of September 30, 2018 and December 31, 2017, respectively	(39,272)	(34,640)
Additional paid-in capital	650,814	648,996
Accumulated comprehensive loss	(122)	(88)
Accumulated deficit	(411,172)	(320,018)
Total Acacia Research Corporation stockholders' equity	200,298	294,301
Noncontrolling interests in operating subsidiaries	1,844	1,358
Total stockholders' equity	202,142	295,659
Total liabilities and stockholders' equity	$ 220,276	$ 308,768