CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 78,718	$ 146,470
Available-for-sale securities	99,910	49,897
Prepaid expenses and other current assets	3,649	3,836
Total Current Assets	182,277	200,203
Property and equipment, net	617	642
Security deposits	219	163
Deferred financing costs, net	11,719	12,336
Total Assets	194,832	213,344
Current Liabilities:
Accounts payable	11,170	13,869
Accrued expenses	1,710	1,962
Interest payable on Senior Convertible Debentures	6,250	2,500
Total Current Liabilities	19,130	18,331
Senior Convertible Debentures	200,000	200,000
Derivative financial instruments, at estimated fair value-warrants	440	172
Total Liabilities	219,570	218,503
Commitments and contingencies
Stockholders' Deficit:
Preferred stock, Authorized 20,000,000 shares and none outstanding, at March 31, 2015 and December 31, 2014
Common stock, par value of $.0001 authorized 200,000,000 shares at March 31, 2015 and December 31, 2014. Issued and outstanding 97,952,062 shares and 96,609,764 shares at March 31, 2015 and December 31, 2014, respectively	10	11
Additional paid-in capital	269,526	261,715
Accumulated deficit	(294,274)	(266,885)
Total Stockholders' Deficit	(24,738)	(5,159)
Total Liabilities and Stockholders' Deficit	$ 194,832	$ 213,344