CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating activities
Net loss	$ (71,244)	$ (57,564)	$ (60,585)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,403	1,445	1,811
Stock-based compensation	13,312	10,394	9,355
Non-cash operating lease cost	1,580
Non-cash interest expense	386	1,248	551
Loss on disposal of property and equipment	15	5
Non-cash tax expense from realized gain on available-for-sale securities			3,825
Gain on sale of investment in marketable equity securities			(3,466)
Changes in operating assets and liabilities:
Accounts receivable	(8,130)	3,663	(5,547)
Inventories	(6,043)	806	(2,092)
Other assets	1,787	(2,744)	1,107
Accounts payable	5,017	5,683	2,487
Accrued liabilities and other non-current liabilities	1,295	6,046	(626)
Manufacturing and development obligations	(6,288)	(266)	680
Deferred product revenue	72	38	265
Net cash used in operating activities	(65,838)	(31,246)	(52,235)
Investing activities
Capital expenditures	(8,935)	(1,144)	(353)
Purchases of investments	(43,907)	(80,701)	(68,792)
Proceeds from maturities and sale of investments	81,027	37,997	69,566
Net cash provided by (used in) investing activities	28,185	(43,848)	421
Financing activities
Net proceeds from equity incentives	3,210	7,848	2,428
Net proceeds from public offering	26,931	85,036	30,197
Net proceeds from revolving line of credit	5,017
Proceeds from loans	39,433		30,000
Repayment of debt	(31,104)	(133)	(19,625)
Net cash provided by financing activities	43,487	92,751	43,000
Net increase (decrease) in cash, cash equivalents and restricted cash	5,834	17,657	(8,814)
Cash, cash equivalents and restricted cash, beginning of period	31,587	13,930	22,744
Cash, cash equivalents and restricted cash, end of period	37,421	31,587	13,930
Supplemental disclosure of cash flow information:
Cash paid for interest	3,077	2,728	2,034
Cash paid for income taxes	229	254	$ 160
Non-cash investing activities:
Non-cash purchases of capital expenditures	$ 2,949	$ 2,222