CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (7,091)	$ (3,289)
Adjustments to reconcile net loss to net cash flows from operating activities:
Depreciation and amortization expense	873	811
Stock-based compensation expense	9,531	7,019
Amortization of premiums and discounts on marketable securities	194	273
Non-cash lease cost	1,076	1,171
Other	4	(20)
Changes in operating assets and liabilities:
Inventory	(1,004)	(966)
Accounts receivable	5,582	5,382
Other current assets	(847)	(320)
Accounts payable	(219)	2,174
Accrued expenses	(3,734)	(1,328)
Operating lease liabilities	(897)	(821)
Net cash provided by operating activities	3,468	10,086
Investing activities:
Purchases of investments	(12,629)	(10,426)
Sales and maturities of investments	5,041	24,955
Expenditures for property and equipment	(3,081)	(2,343)
Net cash (used in) provided by investing activities	(10,669)	12,186
Financing activities:
Net proceeds from common stock issuance	1,465	3,781
Payments on employee’s behalf for taxes related to vesting of restricted stock unit awards	(943)	(1,501)
Other	(19)	(18)
Net cash provided by financing activities	503	2,262
Net (decrease) increase in cash, cash equivalents, and restricted cash	(6,698)	24,534
Cash, cash equivalents, and restricted cash at beginning of period	68,541	33,831
Cash, cash equivalents, and restricted cash at end of period	61,843	58,365
Supplemental disclosure of cash flow information:
Additions to property and equipment included in accounts payable	317	530
Restricted stock held for employee tax remittance included in accounts payable	480	65
Reconciliation of amounts within the condensed consolidated balance sheets:
Cash and cash equivalents	55,659	58,154
Restricted cash	6,184	211
Total cash, cash equivalents, and restricted cash at end of period	$ 61,843	$ 58,365