Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 50,506	$ 54,977
Marketable securities	82,648	112,544
Accounts receivable, net	10,897	10,452
Unbilled revenues	1,706	1,101
Inventories	10,912	9,836
Prepaid expenses and other current assets	3,087	2,907
Total current assets	159,756	191,817
Property, plant and equipment, net	39,146	40,089
Investments in unconsolidated joint venture	28,191	22,532
Other assets	3,427	4,267
Total assets	230,520	258,705
Current liabilities:
Accounts payable	7,666	7,949
Accrued liabilities	10,049	15,005
Current portion of long-term debt	55	65
Deferred revenue	2,637	2,275
Total current liabilities	20,407	25,294
Deferred revenue	300	0
Warrant liability	0	688
Long-term debt	10,369	10,374
Convertible debt, inclusive of derivative liability of $3,680 and $5,914 at March 31, 2014 and December 31, 2013, respectively; and net of unamortized debt discount of $4,229 and $4,610 at March 31, 2014 and December 31, 2013, respectively.	78,630	83,083
Other liabilities	248	318
Total liabilities	109,954	119,757
Commitments and contingencies (Note 12)
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; 70,203,216 and 68,744,534 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	70	69
Additional paid-in capital	464,047	448,990
Accumulated other comprehensive loss	(2,553)	(3,794)
Accumulated deficit	(340,998)	(306,317)
Total stockholders' equity	120,566	138,948
Total liabilities and stockholders' equity	$ 230,520	$ 258,705