Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 19,240	$ 23,273
Accounts receivable, net of allowances of $421 at December 31, 2016 and 2015	5,924	7,329
Inventories	825	992
Prepaid expenses and other assets, current	1,238	1,245
Total current assets	27,227	32,839
Restricted cash	1,624	787
Marketable securities	1,142	1,549
Property and equipment, net	2,155	3,109
Intangible assets, net	0	2,812
Goodwill	3,241	3,241
Other assets, non-current	259	310
Total assets	35,648	44,647
Current liabilities:
Accounts payable	4,232	3,399
Accrued compensation	4,314	3,331
Other accrued liabilities	2,111	2,013
Deferred revenues	1,710	6,098
Total current liabilities	12,367	14,841
Deferred revenues, net of current portion	1,066	3,120
Lease incentive obligation, net of current portion	885	1,310
Other liabilities	2,231	2,497
Total liabilities	16,549	21,768
Commitments and contingencies (Note 13)
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; 41,255 and 40,343 shares issued and outstanding at December 31, 2016 and December 31, 2015, respectively	4	4
Additional paid-in capital	311,164	305,981
Accumulated other comprehensive income	0	405
Accumulated deficit	(292,069)	(283,511)
Total stockholders’ equity	19,099	22,879
Total liabilities and stockholders’ equity	$ 35,648	$ 44,647