Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 392	$ 142
Marketable securities	5,671	3,392
Prepaid expenses and other assets	99	330
Total current assets	6,162	3,864
Property and equipment, net	7	5
Patent portfolios and patent rights, net	8,737	9,799
Deposit	26	26
Total assets	14,932	13,694
Current liabilities
Accounts payable and accrued expenses	260	384
Accrued salaries and benefits	74	645
Warrant liabilities	1,928	2,959
Short-term deferred revenue	1,246	290
Short-term lease liabilities	179	178
Total current liabilities	3,687	4,456
Long-term deferred revenue	3,843	259
Long-term lease liabilities	138	229
Total liabilities	7,668	4,944
Series I redeemable convertible preferred stock, $0.0001 par value; no shares issued and outstanding at June 30, 2016 and December 31, 2015; liquidation preference of $167 per share
Commitments and contingencies
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized; 3,228,612 and 2,539,859 shares issued at June 30, 2016 and December 31, 2015, respectively; 3,228,600 and 2,539,847 shares outstanding at June 30, 2016 and December 31, 2015, respectively
Additional paid-in-capital	144,928	144,287
Treasury stock, at cost, 12 shares at June 30, 2016 and December 31, 2015	(264)	(264)
Accumulated deficit	(137,400)	(135,273)
Total stockholders' equity	7,264	8,750
Total liabilities and stockholders' equity	14,932	13,694
Series A Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series C Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series D Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series D-1 Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series F-1 Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series H Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series J Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series K Preferred Stock [Member]
Stockholders' equity
Preferred Stock