Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities:
Net loss	$ (10,417)	$ (23,966)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	812	795
Gain on disposal of property and equipment	0	(5)
Income tax benefit related to marketable securities	0	(8)
Stock-based compensation	6,207	5,212
Unrealized gain on investment in marketable securities	20	0
Changes in operating assets and liabilities:
Accounts receivable, net	3,556	(1,757)
Inventories, net	206	(24)
Prepaid expenses and other current assets	(1,188)	(1,303)
Contract Assets	(1,868)	0
Other assets	188	(68)
Accounts payable	(1,686)	150
Accrued compensation	409	(519)
Other accrued liabilities	1,332	2,287
Long term lease incentive	(319)	(319)
Other long term liabilities	(391)	(60)
Deferred revenue	(10,235)	3,204
Net cash used in operating activities	(13,374)	(16,381)
Investing activities:
Purchase of property and equipment	(2,074)	(743)
Proceeds from disposal of property and equipment	1	5
Net cash used in investing activities	(2,073)	(738)
Financing activities:
Proceeds from exercises of stock options	4,319	175
Proceeds from issuance of common stock in connection with public offering, net of underwriting discounts and commission	37,497	23,782
Costs incurred in connection with public offering	(180)	(553)
Principal payments on capital lease obligations	(178)	(117)
Taxes paid related to net share settlement of equity awards	(3,140)	(1,670)
Net cash provided by financing activities	38,318	21,617
Net increase in cash, cash equivalents and restricted cash	22,871	4,498
Cash, cash equivalents and restricted cash at the beginning of the period	32,776	20,864
Cash, cash equivalents and restricted cash at the end of the period	55,647	25,362
Supplemental disclosure of cash flow information:
Interest paid	61	131
Income taxes paid	5	32
Supplemental non-cash investing and financing activities:
Equipment acquired under capital leases	0	840
Purchase of property and equipment recorded in accounts payable and accrued expenses	420	20
Cash and cash equivalents	54,225	23,826
Total cash, cash equivalents and restricted cash at the end of the period	$ 32,776	$ 20,864