Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 13,923	$ 19,240
Accounts receivable, net of allowances of $421 at March 31, 2017 and December 31, 2016	5,381	5,924
Inventories	1,124	825
Prepaid expenses and other current assets	1,314	1,238
Total current assets	21,742	27,227
Restricted cash	1,592	1,624
Marketable securities	1,051	1,142
Property and equipment, net	2,752	2,155
Goodwill	3,241	3,241
Other non-current assets	253	259
Total assets	30,631	35,648
Current liabilities:
Accounts payable	3,493	4,232
Accrued compensation	5,334	4,314
Other accrued liabilities	3,055	2,111
Deferred revenue	1,644	1,710
Total current liabilities	13,526	12,367
Deferred revenue, net of current portion	2,180	1,066
Lease incentive obligation, net of current portion	779	885
Financing obligation, net of current portion	255	0
Other long-term liabilities	2,211	2,231
Liabilities	18,951	16,549
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.0001 par value per share; 5,000 shares authorized; none issued and outstanding	0	0
Common stock, $0.0001 par value per share; 100,000 shares authorized; 41,841 shares and 41,255 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	4	4
Additional paid-in capital	311,296	311,164
Accumulated other comprehensive loss	(91)	0
Accumulated deficit	(299,529)	(292,069)
Total stockholders' equity	11,680	19,099
Total liabilities and stockholders' equity	$ 30,631	$ 35,648