CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities
Net loss	$ (59,857)	$ (71,244)	$ (57,564)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,109	2,403	1,445
Stock-based compensation	18,029	13,312	10,394
Non-cash operating lease cost	1,346	1,580
Changes in valuation of warrant investment	(422)
Net loss on sale of available-for-sale securities	234		1,248
Loss on disposal of property and equipment		15	5
Impairment of long-lived assets	274
Non-cash interest expense	478	386
Changes in operating assets and liabilities:
Accounts receivable	(4,284)	(8,130)	3,663
Inventories	(4,030)	(6,043)	806
Other assets	(623)	1,787	(2,744)
Accounts payable	2,236	5,017	5,683
Accrued liabilities and other non-current liabilities	2,760	1,295	6,046
Manufacturing and development obligations		(6,288)	(266)
Deferred product revenue	7	72	38
Net cash used in operating activities	(40,743)	(65,838)	(31,246)
Investing activities
Capital expenditures	(1,615)	(8,935)	(1,144)
Purchases of investments	(98,793)	(43,907)	(80,701)
Proceeds from maturities and sale of investments	50,850	81,027	37,997
Net cash (used in) provided by investing activities	(49,558)	28,185	(43,848)
Financing activities
Net proceeds from equity incentives	11,750	3,210	7,848
Net proceeds from public offerings	76,534	26,931	85,036
Net proceeds from revolving line of credit	3,499	5,017
Proceeds from loans		39,433
Repayment of debt		(31,104)	(133)
Net cash provided by financing activities	91,783	43,487	92,751
Net decrease in cash, cash equivalents and restricted cash	1,482	5,834	17,657
Cash, cash equivalents and restricted cash, beginning of period	37,421	31,587	13,930
Cash, cash equivalents and restricted cash, end of period	38,903	37,421	31,587
Supplemental disclosure of cash flow information:
Cash paid for interest	3,269	3,077	2,728
Cash paid for income taxes	$ 265	229	254
Non-cash investing activities:
Non-cash leasehold improvements		$ 2,949	$ 2,222