Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 9,941	$ 21,692
Short-term investments	32,715
Accounts receivable, net	8,331	3,322
Inventory	6,750	5,380
Prepaid expenses and other	2,999	1,320
Total current assets	60,736	31,714
Restricted cash	201	180
Deferred offering costs	29	1,765
Property and equipment, net	3,065	3,674
Other assets	341	73
Total assets	64,372	37,406
Current liabilities:
Accounts payable	3,354	2,865
Accrued liabilities	7,088	4,481
Deferred revenue, current portion	1,462	878
Deferred rent, current portion	590	764
Long-term debt, current portion	6,136	2,789
Total current liabilities	18,630	11,777
Deferred revenue, net of current portion	803	362
Deferred rent, net of current portion	1,313	1,903
Long-term debt, net of current portion	12,157	9,970
Preferred stock warrant liability		3,532
Total liabilities	32,903	27,544
Commitments and contingencies (Note 13)
Mandatorily redeemable convertible preferred stock, value		103,622
Stockholders' equity (deficit):
Preferred stock, value
Common stock, value	1
Additional paid in capital	158,278
Other comprehensive income	22
Accumulated deficit	(126,832)	(93,760)
Total stockholders' equity (deficit)	31,469	(93,760)
Total liabilities, mandatorily redeemable convertible preferred stock and stockholders' equity (deficit)	$ 64,372	$ 37,406