Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 55,440	$ 30,818
Marketable securities	183,671	118,187
Accounts receivable	7,320	3,280
Unbilled revenues	2,276	3,150
Inventories	6,668	6,890
Prepaid expenses and other current assets	5,121	2,954
Total current assets	260,496	165,279
Property, plant and equipment, net	32,390	32,225
Investments in unconsolidated joint ventures	23,588	19,047
Other assets	889	473
Total assets	317,363	217,024
Current liabilities:
Accounts payable	5,526	7,552
Accrued liabilities	11,883	9,320
Current portion of long-term debt	60	7,331
Deferred revenue	1,966	292
Other current liabilities		443
Total current liabilities	19,435	24,938
Deferred revenue	1,467
Warrant liability	781	835
Long-term debt	10,424	7,637
Convertible debt, inclusive of derivative liability of $3,861 and net of unamortized debt discount of $8,132 as of March 31, 2013	120,729
Other liabilities	238	303
Total liabilities	153,074	33,713
Commitments and contingencies (Note 12)
Stockholders' equity:
Common stock, par value $0.001 - 150,000,000 shares authorized at March 31, 2013 and December 31, 2012; 61,786,103 and 61,000,724 shares issued and outstanding at March 31, 2013 and December 31, 2012, respectively	62	61
Additional paid-in capital	381,135	373,577
Accumulated other comprehensive loss	(455)	(399)
Accumulated deficit	(216,453)	(189,928)
Total stockholders' equity	164,289	183,311
Total liabilities and stockholders' equity	$ 317,363	$ 217,024