Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Current Assets:
Cash and cash equivalents	$ 44,711	$ 86,283
Accounts receivable	0	67
Inventory, net	27	112
Prepaid expenses and other current assets	821	777
Total current assets	45,559	87,239
Property and equipment, net	1,637	1,656
Restricted cash	225	325
Other assets	78	97
Total Assets	47,499	89,317
Current Liabilities:
Accounts payable	350	1,433
Accrued expenses	6,116	4,785
Deferred revenue	43	139
Common stock warrant liability	1,258	5,425
Equipment loans, current portion	62	73
Total current liabilities	7,829	11,855
Long-term debt, $30,000 net of discount of $9,698 at December 31, 2014 and $11,646 at December 31, 2013	20,302	18,354
Equipment loans, non-current portion	0	69
Other liabilities	169	538
Total liabilities	28,300	30,816
Stockholders' Equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.001 par value; 250,000,000 and 150,000,000 shares authorized at December 31, 2014 and 2013, respectively; 85,607,806 and 84,659,111 shares issued at December 31, 2014 and 2013, respectively; 85,586,914 and 84,638,219 shares outstanding at December 31, 2014 and 2013, respectively	86	85
Additional paid-in capital	546,175	541,420
Accumulated deficit	(524,008)	(479,950)
Treasury stock (at cost); 20,892 shares at December 31, 2013 and 2012	(3,054)	(3,054)
Total stockholders' equity	19,199	58,501
Total liabilities & stockholders' equity	$ 47,499	$ 89,317