Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 63,487	$ 128,809
Trading securities - debt	90,482	33,642
Trading securities - equity	10,934	3,012
Accounts receivable	15,308	32,884
Prepaid expenses and other current assets	3,289	3,125
Total current assets	183,500	201,472
Investment at fair value (Note 5)	9,070	7,459
Other investments (Note 5)	0	8,195
Patents, net of accumulated amortization	9,534	6,587
Other non-current assets	1,658	236
Total assets	203,762	223,949
Current liabilities:
Accounts payable and accrued expenses	9,461	8,347
Royalties and contingent legal fees payable	10,518	22,688
Other current liabilities	35	0
Total current liabilities	20,014	31,035
Other liabilities	2,131	1,674
Total liabilities	22,145	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; 50,132,871 and 49,639,319 shares issued and outstanding as of June 30, 2019 and December 31, 2018, respectively	50	50
Treasury stock, at cost, 2,919,828 shares as of June 30, 2019 and December 31, 2018	(39,272)	(39,272)
Additional paid-in capital	651,688	651,156
Accumulated deficit	(432,682)	(422,541)
Total Acacia Research Corporation stockholders' equity	179,784	189,393
Noncontrolling interests	1,833	1,847
Total stockholders' equity	181,617	191,240
Total liabilities and stockholders' equity	$ 203,762	$ 223,949