CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net loss	$ (21,721)	$ (20,812)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of property and equipment and operating lease assets	626	544
Amortization of investment discount	(180)	19
Equity-based compensation	3,397	5,602
Amortization of debt discount and issuance costs	2,387	158
Realized gain on sale of investments	(2)	0
Loss on disposal of property and equipment	329	11
(Increase) decrease in assets:
Accounts receivable	(90)	881
Inventory	(1,567)	(1,917)
Prepaid expense and other	(1,041)	(989)
Increase (decrease) in liabilities:
Accounts payable	1,151	701
Accrued liabilities, and other	(1,790)	733
Accrued interest	(1,071)	0
Deferred revenue and income	74	(1,003)
Deferred compensation	(7)	4
Net cash used in operating activities	(19,505)	(16,068)
Cash flows from investing activities:
Purchases of equipment	(37)	(1,294)
Purchase of marketable securities	(12,826)	(9,356)
Proceeds from sales of marketable securities	9,000	3,000
Maturities of marketable securities	28,662	20,125
Net cash provided by investing activities	24,799	12,475
Cash flows from financing activities:
Proceeds from issuance of common stock	139	134
Proceeds from exercise of options	3,677	1,112
Proceeds from issuance of convertible note	0	150,000
Prepayment of forward stock repurchase transaction	0	(45,069)
Payment of debt issuance costs	0	(4,330)
Net cash provided by financing activities	3,816	101,847
Effect of exchange rate on cash	(61)	80
Increase in cash and cash equivalents	9,049	98,334
Cash and cash equivalents, beginning of period	66,260	28,513
Cash and cash equivalents, end of period	75,309	126,847
Non-cash investing activities:
Transfer of instruments from inventory to property and equipment	769	0
Supplemental cash flow information:
Interest paid	2,144	0
Income taxes paid	$ 2	$ 0