Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net loss	$ (78,739)	$ (54,732)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	14,125	15,405
Depreciation and amortization	3,504	2,880
Amortization of deferred financing costs	732	709
Amortization of premium (accretion of discount) on short-term investments, net	1,200	(2,401)
Non-cash operating lease cost	1,954	1,671
Allowance for inventory obsolescence and accounts receivable credit loss	1,708	1,369
Changes in operating assets and liabilities:
Accounts receivable	7,920	(1,191)
Inventory	(11,531)	(7,048)
Prepaid expenses and other assets	(1,827)	(5,684)
Accounts payable	2,063	6,041
Accrued liabilities	682	553
Accrued compensation and other employee benefits	(3,453)	(806)
Customer deposits	310	(149)
Deferred revenue and other liabilities	1,026	1,306
Operating lease liabilities	(2,397)	(2,090)
Net cash used in operating activities	(62,723)	(44,167)
Investing activities
Purchases of property and equipment	(7,635)	(3,784)
Purchase of internal-use software assets	(4,118)	0
Payments to Acquire Intangible Assets	(750)	0
Proceeds from sale of short-term investments	4,000	4,000
Proceeds from maturity of short-term investments	134,974	24,764
Purchases of short-term investments	(45,800)	(235,263)
Net cash provided by (used in) investing activities	80,671	(210,283)
Financing activities
Tax withholdings related to net share settlements of restricted stock units	(1,504)	(2,585)
Proceeds from issuance of common stock for employee stock purchase plan	1,502	1,192
Proceeds from exercise of stock options	1,300	4,503
Repayment of finance lease obligations	(183)	(119)
Net cash provided by financing activities	1,115	2,991
Effect of exchange rate changes on cash and cash equivalents	(104)	(9)
Net increase (decrease) in cash and cash equivalents	18,959	(251,468)
Cash and cash equivalents
Beginning of period	107,068	411,848
End of period	$ 126,027	$ 160,380