Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 63	$ 197
Marketable securities	5,574	3,998
Prepaid expenses and other assets	228	150
Total current assets	5,865	4,345
Property and equipment, net	2	3
Patent portfolios and patent rights, net	3,240	3,578
Investments at fair value	1,045	1,020
Deposit	26	26
Total assets	10,178	8,972
Current liabilities
Accounts payable and accrued expenses	166	56
Accrued salaries and benefits	625	695
Warrant liabilities	634	822
Short-term deferred revenue		957
Short-term lease liabilities		48
Total current liabilities	1,425	2,578
Long-term deferred revenue		2,288
Total liabilities	1,425	4,866
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized; 8,517,132 and 6,234,910 shares issued at March 31, 2018 and December 31, 2017, respectively; 8,517,120 and 6,234,898 shares outstanding at March 31, 2018 and December 31, 2017, respectively	1
Additional paid-in-capital	152,312	149,425
Treasury stock, at cost, 12 shares at March 31, 2018 and December 31, 2017	(264)	(264)
Accumulated deficit	(143,296)	(145,055)
Total stockholders' equity	8,753	4,106
Total liabilities and stockholders' equity	10,178	8,972
Series D Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series D-1 Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.