Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net loss	$ (23,738)	$ (22,734)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,595	1,711
Gain on disposals of assets, net	(3)	0
Gain on debt retirement	0	(106)
Amortization of (discounts) premiums on investments, net	(397)	(203)
Stock-based compensation expense	2,581	3,131
Shares issued as payment for services	528	545
Accretion of debt discount and amortization of deferred financing costs	0	34
Deferred income taxes	(29)	(55)
Receivables:
Trade	30	(793)
Other	383	(925)
Prepaid expenses and other	699	743
Other assets	4	(27)
Accounts payable	2,653	(249)
Accrued compensation and benefits	1,722	1,936
Other accrued liabilities	(126)	(1,597)
Deferred revenue	(32)	22
Lease liabilities	40	195
Other long-term liabilities	0	(16)
Net cash used in operating activities	(14,090)	(18,388)
Cash flows from investing activities
Purchases of investments	(17,190)	(108,163)
Sales and maturities of investments	45,583	57,909
Purchases of property, plant and equipment	(4,351)	(154)
Proceeds from sale of assets	3	0
Net cash provided by (used in) investing activities	24,045	(50,408)
Cash flows from financing activities
Proceeds from issuance of shares, net of issuance costs	0	73,501
Payments of long-term debt and convertible notes, including cost to retire of $57 in 2023	0	(29,327)
Net cash provided by financing activities	0	44,174
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	(60)	(28)
Net increase (decrease) in cash, cash equivalents, and restricted cash	9,895	(24,650)
Cash, cash equivalents, and restricted cash
Beginning of period	7,848	48,596
End of period	17,743	23,946
Supplemental disclosure of cash flow information
Cash paid during the period for interest	3	924
Accrued compensation paid in equity awards	0	3,361
Purchases of property and equipment included in accounts payable and other accrued liabilities	2,109	24
Issuance costs included in accounts payable and other accrued liabilities	0	719
Cash, cash equivalents, and restricted cash
Cash and cash equivalents	17,478
Restricted cash included in other assets	265
Cash, cash equivalents, and restricted cash	$ 17,743	$ 23,946