Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 1,306	$ 2,212
Marketable securities – unrestricted	16,843	27,241
Marketable securities – restricted	14,374	14,500
Inventories	0	453
Prepaid expenses and other current assets	359	322
Total current assets	32,882	44,728
Property and equipment, net	4,991	5,292
Patent and trademark rights, net	1,069	1,034
Construction in progress	7,065	6,580
Other assets	136	65
Total assets	46,143	57,699
Current liabilities:
Accounts payable	967	2,157
Accrued expenses	1,805	3,395
Margin account loan	7,051	7,051
Current portion of capital lease	35	46
Total current liabilities	9,858	12,649
Long-term liabilities
Long-term portion of capital lease	37	55
Redeemable warrants	104	295
Total liabilities	9,999	12,999
Commitments and contingencies
Stockholders’ equity:
Preferred stock, par value $0.01 per share, authorized 5,000,000; issued and outstanding; none	0	0
Common stock, par value $0.001 per share, authorized 350,000,000 shares; issued and outstanding 167, 229,903 and 166,490,190, respectively	167	166
Additional paid-in capital	289,053	288,671
Accumulated other comprehensive loss	(1,088)	(43)
Accumulated deficit	(251,988)	(244,094)
Total stockholders’ equity	36,144	44,700
Total liabilities and stockholders’ equity	$ 46,143	$ 57,699