CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and cash equivalents	$ 102,732	$ 66,029
Cash held in escrow		6,434
Marketable securities	70,231	110,957
Restricted marketable securities	6	10
Prepaid expenses and other current assets	1,334	2,408
Total current assets	174,303	185,838
Property and equipment, net	164	193
Ownership interests in and advances to partner companies and funds (of which $19,363 and $20,972 are measured at fair value at June 30, 2013 and December 31, 2012, respectively)	143,100	148,639
Loan participations receivable	8,310	7,085
Available-for-sale securities	18	58
Long-term marketable securities	7,146	29,059
Other assets	3,077	3,272
Total Assets	336,118	374,144
Current Liabilities:
Convertible senior debentures-current	470
Accounts payable	203	610
Accrued compensation and benefits	3,634	4,050
Accrued expenses and other current liabilities	3,631	2,601
Total current liabilities	7,938	7,261
Other long-term liabilities	3,862	3,921
Convertible senior debentures-non-current	48,970	48,991
Total Liabilities	60,770	60,173
Commitments and contingencies
Equity:
Preferred stock, $0.10 par value; 1,000 shares authorized
Common stock, $0.10 par value; 83,333 shares authorized; 20,977 and 20,968 shares issued and outstanding at June 30, 2013 and December 31, 2012, respectively	2,098	2,097
Additional paid-in capital	817,384	815,946
Accumulated deficit	(544,134)	(504,072)
Total Equity	275,348	313,971
Total Liabilities and Equity	$ 336,118	$ 374,144