CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 61,695	$ 146,470
Available-for-sale securities	99,984	49,897
Prepaid expenses and other current assets	2,287	3,836
Total Current Assets	163,966	200,203
Property and equipment, net	584	642
Security deposits	219	163
Total Assets	164,769	201,008
Current Liabilities:
Accounts payable	10,606	13,869
Accrued expenses	3,934	1,962
Interest payable on Senior Convertible Debentures	2,222	2,500
Total Current Liabilities	16,762	18,331
Senior Convertible Debentures, net of deferred financing costs of $9,820 and $12,336 as of June 30, 2015 and December 31, 2014, respectively	167,967	187,664
Derivative financial instruments, at estimated fair value-warrants	1,981	172
Total Liabilities	$ 186,710	$ 206,167
Commitments and contingencies
Stockholders' Deficit:
Preferred stock, Authorized 20,000,000 shares and none outstanding, at June 30, 2015 and December 31, 2014
Common stock, par value of $.0001, 350,000,000 shares and 200,000,000 shares authorized at June 30, 2015 and December 31, 2014, respectively. Issued and outstanding 107,188,192 shares and 96,609,764 shares at June 30, 2015 and December 31, 2014, respectively.	$ 12	$ 11
Additional paid-in capital	305,989	261,715
Accumulated deficit	(327,942)	(266,885)
Total Stockholders' Deficit	(21,941)	(5,159)
Total Liabilities and Stockholders' Deficit	$ 164,769	$ 201,008