Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 48,242	$ 42,689
Marketable securities	69,003	164,619
Accounts receivable, net	4,270	4,598
Unbilled revenues	271	3,002
Inventories	12,818	15,334
Prepaid expenses and other current assets	4,755	3,685
Total current assets	139,359	233,927
Property, plant and equipment, net	32,119	36,080
Investment in unconsolidated joint venture	36,185	40,934
Other assets	1,379	1,648
Total assets	209,042	312,589
Current liabilities:
Accounts payable	5,909	8,319
Accrued liabilities	12,173	14,079
Current portion of long-term debt	0	6
Deferred revenue	777	1,050
Total current liabilities	18,859	23,454
Deferred revenue	500	150
Convertible debt, inclusive of derivative liabilities of $56 and $83 at September 30, 2015 and December 31, 2014, respectively; and net of unamortized debt discounts of $9,357 and $11,124 at September 30, 2015 and December 31, 2014, respectively.	201,831	200,091
Other liabilities	7,389	2,518
Total liabilities	$ 228,579	$ 226,213
Commitments and contingencies
Stockholders' equity:
Preferred stock, par value $0.001—5,000,000 shares authorized; 0 shares issued and outstanding	$ 0	$ 0
Common stock, par value $0.001—150,000,000 shares authorized; 80,536,377 and 79,388,069 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	80	79
Additional paid-in capital	578,963	565,769
Accumulated other comprehensive loss	(23,368)	(11,014)
Accumulated deficit	(575,212)	(468,458)
Total stockholders’ (deficit) equity	(19,537)	86,376
Total liabilities and stockholders’ (deficit) equity	$ 209,042	$ 312,589