Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 10,755	$ 21,692
Accounts receivable, net	4,779	3,322
Inventory	5,627	5,380
Prepaid expenses and other	2,533	1,320
Total current assets	23,694	31,714
Restricted cash	180	180
Deferred offering costs	3,384	1,765
Property and equipment, net	3,028	3,674
Other assets	204	73
Total assets	30,490	37,406
Current liabilities:
Accounts payable	2,727	2,865
Accrued liabilities	5,689	4,481
Deferred revenue, current portion	1,086	878
Deferred rent, current portion	610	764
Long-term debt, current portion	2,675	2,789
Total current liabilities	12,787	11,777
Deferred revenue, net of current portion	489	362
Deferred rent, net of current portion	1,684	1,903
Long-term debt, net of current portion	15,047	9,970
Preferred stock warrant liability	2,513	3,532
Total liabilities	32,520	27,544
Mandatorily redeemable convertible preferred stock, $0.0001 par value per share, 8,979 shares authorized; 8,118 shares issued and outstanding	108,275	103,622
Stockholders' deficit
Common stock, $0.0001 par value, 11,713 shares authorized; 583 and 411 shares issued and outstanding, respectively
Accumulated deficit	(110,305)	(93,760)
Total stockholders' deficit	(110,305)	(93,760)
Total liabilities, mandatorily redeemable convertible preferred stock and stockholders' deficit	$ 30,490	$ 37,406