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	$ (25,603)	$ (19,718)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,274	1,086
Stock-based compensation expense	2,234	2,261
Amortization of debt discount	779	256
Loss on disposal of assets and impairment charges		173
Deferred income taxes	2	48
Changes in operating assets and liabilities:
Receivables, net	3,414	(34,728)
Prepaid expenses and other assets	(2,176)	3,748
Inventories	2,523	(3,101)
Accounts payable and accrued expenses	(12,323)	4,430
Net cash used in operating activities	(29,876)	(45,545)
Cash flows from investing activities:
Purchase of property and equipment	(7,341)	(1,736)
Payments for licenses	(1,088)	(64)
Purchases of short-term investments	(55,784)	(23,571)
Sales and maturities of short-term investments	71,250	14,920
Net cash provided by (used in) investing activities	7,037	(10,451)
Cash flows from financing activities:
Proceeds from issuance of debt		435
Proceeds from exercise of stock options	852	344
Repayment of finance lease obligations and long-term debt	(98)	(47)
Net cash provided by financing activities	754	732
Net decrease in cash, cash equivalents, and restricted cash	(22,085)	(55,264)
Cash, cash equivalents, and restricted cash, beginning of period	86,087	127,674
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	478	(427)
Cash, cash equivalents, and restricted cash, end of period (See Note 3)	64,480	71,983
Supplemental cash flow disclosures
Interest paid	7,708	1,390
Non-cash investing and financing activities:
Accrued purchases of property and equipment	1,215	1,009
Accrued purchases of licenses	$ 1,800	500
ROU assets derecognized from modification of operating lease obligations		(468)
ROU assets recognized in exchange for operating lease obligations		$ 353