Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (33,589)	$ (20,855)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation	2,654	2,619
Stock-based compensation	10,123	2,531
Change in operating lease right-of-use assets	994	944
Non-cash interest and other (income) expense related to debt and note receivable agreements	36	34
Provision for excess and obsolete inventory	330	79
Loss on disposal and impairment of property and equipment	31	61
Changes in operating assets and liabilities:
Trade accounts receivable	(6,820)	(902)
Inventory	(5,710)	(4,547)
Prepaid expenses, other current assets and other assets	(639)	(1,143)
Trade accounts payable	4,512	1,404
Deferred revenue	2,942	(1,441)
Accrued expenses and other current liabilities	1,872	1,249
Operating lease liabilities	(831)	(1,012)
Net cash used in operating activities	(24,095)	(20,979)
Cash flows from investing activities:
Purchase of property and equipment	(4,382)	(1,316)
Net cash used in investing activities	(4,382)	(1,316)
Cash flows from financing activities:
Payment of debt issuance costs	(358)	0
Proceeds from issuance of common stock upon exercise of stock options	8,347	432
Proceeds from issuance of common stock under employee stock purchase plan	2,157	0
Net cash provided by financing activities	10,146	432
Net decrease in cash and cash equivalents and restricted cash	(18,331)	(21,863)
Cash and cash equivalents and restricted cash at beginning of period	233,678	81,303
Cash and cash equivalents and restricted cash at end of period	$ 215,347	$ 59,440