Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 803	$ 2,212
Marketable securities- unrestricted	17,391	27,241
Marketable securities- restricted	0	14,500
Inventories	0	453
Prepaid expenses and other current assets	358	322
Total current assets	18,552	44,728
Property and equipment, net	5,053	5,292
Patent and trademark rights, net	1,080	1,034
Construction in progress	7,046	6,580
Other assets	136	65
Total assets	31,867	57,699
Current liabilities:
Accounts payable	1,271	2,157
Accrued expenses	1,228	3,395
Margin account loan	0	7,051
Current portion of capital lease	33	46
Total current liabilities	2,532	12,649
Long-term liabilities:
Long-term portion of capital lease	23	55
Redeemable warrants	14	295
Total liabilities	2,569	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 168,660,370 and 166,490,190, respectively	168	166
Additional paid-in capital	289,563	288,671
Unrealized loss	(114)	(43)
Accumulated deficit	(260,319)	(244,094)
Total stockholders’ equity	29,298	44,700
Total liabilities and stockholders’ equity	$ 31,867	$ 57,699