Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 16,121	$ 41,228
Trade accounts receivable, net	4,138	5,643
Inventory, net	13,185	12,886
Prepaid expenses and other current assets	2,044	2,254
Total current assets	35,488	62,011
Property and equipment, net	13,414	13,561
Other assets	4,496	5,114
Total assets	53,398	80,686
Current liabilities:
Accounts payable	6,337	4,592
Accrued expenses	12,052	14,343
Common stock warrant liabilities	12,488	9,493
Accrued compensation	2,518	4,226
Total current liabilities	33,395	32,654
Long-term debt, less current portion	28,638	28,481
Other long-term liabilities	7,452	5,078
Commitments and contingencies
Stockholders' equity:
Common stock	101	101
Additional paid-in capital	347,592	343,763
Accumulated deficit	(363,780)	(329,391)
Total stockholders’ equity (deficit)	(16,087)	14,473
Total liabilities and stockholders’ equity (deficit)	$ 53,398	$ 80,686