Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ 83,009	$ 104,916
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and other	6,630	3,917
Loss on disposal of property and equipment	442	2,170
Stock-based compensation expense	16,631	11,817
Interest due on long-term debt	146	109
Amortization of debt discount and accretion related to debt	737	448
Accretion of asset retirement obligations	135	125
Loss on extinguishment of debt	0	1,237
Changes in operating assets and liabilities:
Prepaid expenses	223	(1,822)
Accounts receivable, related party	234	174
Grants revenue receivable	0	7,100
Other assets	(289)	8
Operating lease right-of-use assets and liabilities	243	(87)
Accounts payable	(757)	499
Accrued liabilities	(3,268)	(2,672)
Other liabilities, related party	(11,853)	12,325
Other liabilities	(472)	0
Deferred revenue	47,735	(8,903)
Deferred revenue, related party	(3,895)	(5,326)
Net cash used in operating activities	(30,387)	(83,797)
Cash flows from investing activities:
Purchases of property and equipment	(3,996)	(7,392)
Proceeds on sale of equipment	0	15
Purchase of marketable securities	(210,994)	(132,809)
Sales of marketable securities	152,550	105,523
Net cash used in investing activities	(62,440)	(34,663)
Cash flows from financing activities:
Payments of capital and finance lease obligations	(1)	(18)
Proceeds from issuance of long-term debt and warrants, net	19,828	14,677
Repayment of long-term debt	0	(5,176)
Proceeds from stock option exercises	1,620	1,040
Proceeds from issuance of common stock and warrants, net offering expenses	71,145	48,372
Net cash provided by financing activities	92,592	58,895
Net increase/(decrease) in cash, cash equivalents, and restricted cash	(235)	(59,565)
Cash, cash equivalents and restricted cash, beginning of period	28,886	88,451
Cash, cash equivalents and restricted cash, end of period	28,651	28,886
Reconciliation of cash, cash equivalents and restricted cash
Cash and cash equivalents	24,983	25,218
Restricted cash included in Other assets	$ 3,668	$ 3,668
Restricted Cash and Cash Equivalents, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Cash, cash equivalents and restricted cash, end of period	$ 28,651	$ 28,886
Supplemental Cash Flow Information
Cash paid for interest	2,248	931
Non-Cash Investing and Financing Activities
Fixed asset additions in accounts payable and accrued expenses	$ 81	$ 980