Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net loss	$ 27,944,000	$ 31,905,000
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,507,000	2,454,000
Net amortization/(accretion) of premiums/discounts on investments	(78,000)	30,000
Amortization of deferred debt issuance costs	583,000	493,000
Stock-based compensation	5,799,000	5,602,000
Provision for bad debt	34,000	32,000
Non-cash inventory adjustments	809,000	565,000
Other non-cash adjustments	(13,000)	(123,000)
Changes in operating assets and liabilities:
Accounts receivable	3,501,000	1,795,000
Inventories	(353,000)	2,563,000
Prepaid expenses and other assets	(340,000)	119,000
Accounts payable	(1,853,000)	(3,134,000)
Accrued compensation	(853,000)	(1,170,000)
Other current and non-current liabilities	(622,000)	(124,000)
Net cash used in operating activities	(16,437,000)	(28,167,000)
Investing activities:
Purchases of property and equipment	(924,000)	(2,535,000)
Purchases of marketable securities	(23,622,000)	(10,496,000)
Proceeds from sales of marketable securities	0	13,896,000
Maturities of marketable securities	42,600,000	4,100,000
Net cash provided by investing activities	18,054,000	4,965,000
Financing activities:
Proceeds from issuance of common stock	535,000	86,835,000
Costs incurred in conjunction with public offering	0	(5,171,000)
Principal repayment of borrowings	(45,000)	(964,000)
Proceeds from borrowings	0	15,000,000
Payments associated with debt issuance	(20,000)	(187,000)
Proceeds from stock option exercises	(22,000)	(170,000)
Net cash provided by (used in) financing activities	492,000	95,683,000
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	28,000	(13,000)
Net increase (decrease) in cash, cash equivalents, and restricted cash	2,137,000	72,468,000
Cash, cash equivalents, and restricted cash at beginning of year	27,512,000	16,717,000
Cash, cash equivalents, and restricted cash at end of period	29,649,000	89,185,000
Non-cash investing and financing activities:
Transfer of systems to property and equipment from inventory	956,000	(1,534,000)
Property and equipment included in accounts payable	168,000	713,000
Intellectual property acquisitions included in other current liabilities	0	500,000
Supplemental cash flow information:
Cash paid for income taxes, net	113,000	54,000
Cash paid for interest	$ 1,003,000	$ 574,000