Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (28,556)	$ (36,802)
Adjustments to reconcile net loss to cash used in operating activities
Depreciation	521	198
Amortization of right-of-use assets	430	401
Stock-based compensation expense	4,640	4,651
Provision for inventory	540
Non cash interest expense	226	106
Amortization (accretion) of premium (discount) on marketable securities	251	(59)
Loss on disposal of fixed assets		262
Amortization of debt discount and debt issuance costs	2,485	2,262
Premium paid on securities purchased	3
Changes in operating assets and liabilities:
Accounts receivable	(340)	6,753
Inventory	2,178	(3,101)
Prepaid expenses and other current assets	(2,189)	(441)
Accounts payable	124	(3,035)
Accrued expenses and other current liabilities	1,570	1,025
Lease liabilities	(357)	(417)
Net cash used in operating activities	(18,474)	(28,197)
Cash flows from investing activities
Purchases of property and equipment	(801)	(3,244)
Purchases of marketable securities	(2,000)
Sale and redemption of marketable securities	13,750	41,198
Net cash provided by investing activities	10,949	37,954
Cash flows from financing activities
Proceeds from revolving line of credit		20,000
Proceeds from issuance of common stock (net of issuance costs)	1,700
Payments of public offering costs	(125)
Payments on notes payable	(3,055)
Proceeds from the exercise of stock options	8	9
Net cash (used in) provided by financing activities	(1,472)	20,009
Net (decrease) increase in cash and cash equivalents	(8,997)	29,766
Cash and cash equivalents at beginning of period	107,704	82,253
Cash and cash equivalents at end of period	98,707	112,019
Non-cash investing and financing activities
Purchases of property and equipment in accounts payable and accrued expenses	30	1,436
Supplemental disclosures of cash flow information
Cash paid for interest	$ 955	$ 703