Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 66,861	$ 128,809
Trading securities - debt	86,390	33,642
Trading securities - equity	16,080	3,012
Accounts receivable	1,799	32,884
Prepaid expenses and other current assets	2,329	3,125
Total current assets	173,459	201,472
Investment at fair value (Note 5)	2,674	7,459
Other investments (Note 5)	0	8,195
Patents, net of accumulated amortization	8,671	6,587
Other non-current assets	2,126	236
Total assets	186,930	223,949
Current liabilities:
Accounts payable and accrued expenses	8,268	8,347
Royalties and contingent legal fees payable	2,274	22,688
Other current liabilities	29	0
Total current liabilities	10,571	31,035
Other liabilities	2,050	1,674
Total liabilities	12,621	32,709
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; 50,343,305 and 49,639,319 shares issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	50	50
Treasury stock, at cost, 2,919,828 shares as of September 30, 2019 and December 31, 2018	(39,272)	(39,272)
Additional paid-in capital	651,988	651,156
Accumulated deficit	(440,290)	(422,541)
Total Acacia Research Corporation stockholders' equity	172,476	189,393
Noncontrolling interests	1,833	1,847
Total stockholders' equity	174,309	191,240
Total liabilities and stockholders' equity	$ 186,930	$ 223,949