Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 33,985	$ 28,947
Restricted cash, current portion	1,322	901
Short-term investments	196,597	201,586
Accounts receivable, net of allowance of $1,203 in 2016 and $971 in 2015	6,105	5,862
Inventory	6,689	8,093
Prepaid expenses and other current assets	3,927	5,337
Total current assets	248,625	250,726
Property and equipment, net	15,098	12,710
Restricted cash, long term portion	342	683
Other assets	1,683	1,121
Total assets	265,748	265,240
Current liabilities:
Accounts payable	8,980	7,332
Accrued compensation	8,899	8,552
Other accrued liabilities	20,715	18,708
Deferred revenue	215	144
Short-term debt financing	42,205	42,090
Warrants	3,139	3,649
Total current liabilities	84,153	80,475
Total liabilities	$ 84,153	$ 80,475
Commitments and contingencies (Note 6)
Stockholders’ equity:
Common stock	$ 6	$ 5
Additional paid in capital	439,962	436,259
Accumulated deficit	(258,769)	(250,083)
Accumulated other comprehensive income (loss)	396	(1,416)
Total stockholders’ equity	181,595	184,765
Total liabilities and stockholders’ equity	$ 265,748	$ 265,240