CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash and cash equivalents	$ 20,751	$ 22,058
Marketable securities	4,452	8,384
Trading securities	3,761	0
Prepaid expenses and other current assets	4,644	2,109
Total current assets	33,608	32,551
Property and equipment, net	1,513	1,873
Ownership interests in and advances to partner companies	134,691	183,470
Long-term marketable securities	0	7,302
Long-term restricted cash equivalents	6,336	6,336
Other assets	316	296
Total Assets	176,464	231,828
Current Liabilities:
Accounts payable	155	140
Accrued compensation and benefits	3,321	3,498
Accrued expenses and other current liabilities	1,851	2,223
Convertible senior debentures - current	40,485	0
Total current liabilities	45,812	5,861
Other long-term liabilities	3,535	3,630
Credit facility	45,321	0
Convertible senior debentures - non-current	0	52,560
Total Liabilities	94,668	62,051
Commitments and contingencies
Equity:
Preferred stock, $0.10 par value; 1,000 shares authorized	0	0
Common stock, $0.10 par value; 83,333 shares authorized; 21,573 issued at December 31, 2017 and 2016, respectively	2,157	2,157
Additional paid-in capital	812,536	816,016
Treasury stock, at cost; 999 and 1,209 shares at December 31, 2017 and 2016, respectively	(17,308)	(21,061)
Accumulated deficit	(715,476)	(626,904)
Accumulated other comprehensive loss	(113)	(431)
Total Equity	81,796	169,777
Total Liabilities and Equity	$ 176,464	$ 231,828