Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 1,588	$ 2,212
Marketable securities – unrestricted	21,410	27,241
Marketable securities – restricted	14,837	14,500
Inventories	453	453
Prepaid expenses and other current assets	293	322
Total current assets	38,581	44,728
Property and equipment, net	5,131	5,292
Patent and trademark rights, net	1,076	1,034
Construction in progress	6,806	6,580
Other assets	65	65
Total assets	51,659	57,699
Current liabilities:
Accounts payable	1,665	2,157
Accrued expenses	1,269	3,395
Margin account loan	7,051	7,051
Current portion of capital lease	43	46
Total current liabilities	10,028	12,649
Long-term liabilities
Long-term portion of capital lease	45	55
Redeemable warrants	206	295
Total liabilities	10,279	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, 074,114 and 166,490,190, respectively	167	166
Additional paid-in capital	288,925	288,671
Accumulated other comprehensive loss	(7)	(43)
Accumulated deficit	(247,705)	(244,094)
Total stockholders’ equity	41,380	44,700
Total liabilities and stockholders’ equity	$ 51,659	$ 57,699