Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 25,324	$ 41,228
Trade accounts receivable, net	5,755	5,643
Inventory, net	12,663	12,886
Prepaid expenses and other current assets	2,995	1,968
Total current assets	46,737	61,725
Property and equipment, net	13,912	13,561
Other assets	4,921	5,400
Total assets	65,570	80,686
Current liabilities:
Accounts payable	4,541	4,592
Accrued expenses	14,909	14,343
Common stock warrant liabilities	13,751	9,493
Accrued compensation	2,982	4,226
Total current liabilities	36,183	32,654
Long-term debt, less current portion	28,557	28,481
Other long-term liabilities	5,826	5,078
Commitments and contingencies
Stockholders' equity:
Common stock	101	101
Additional paid-in capital	345,349	343,763
Accumulated deficit	(350,446)	(329,391)
Total stockholders’ equity (deficit)	(4,996)	14,473
Total liabilities and stockholders’ equity (deficit)	$ 65,570	$ 80,686