Condensed Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 36,964	$ 82,647
Investment securities, available-for-sale	55,926	32,720
Inventory	1,833	1,780
Other current assets	1,027	2,283
Total current assets	95,750	119,430
Property and equipment, net	3,419	3,026
Operating lease right-of-use asset	5,482	5,577
Restricted cash	1,418	1,092
Intangible assets, net	95	115
Other assets	1,028	985
Total assets	107,192	130,225
Current liabilities
Accounts payable	1,415	3,584
Accrued liabilities	1,416	1,170
Contract liabilities	4,601	5,265
Other current liabilities		1,181
Current portion of long-term debt	9	392
Current portion of operating lease liability	590	849
Current portion of finance lease obligations	24	21
Total current liabilities	8,055	12,462
Operating lease liability, net of current portion	5,029	4,983
Finance lease obligations, net of current portion	8	26
Total liabilities	13,092	17,471
Shareholders' equity
Preferred stock, par value $0.001; 25,000 shares authorized; no and no shares issued and outstanding
Common stock, par value $0.001; 210,000 shares authorized; 165,438 and 164,363 shares issued and outstanding at June 30, 2022 and December 31, 2021, respectively	165	164
Additional paid-in capital	750,311	742,042
Accumulated other comprehensive loss	(178)	(19)
Accumulated deficit	(656,198)	(629,433)
Total shareholders' equity	94,100	112,754
Total liabilities and shareholders' equity	$ 107,192	$ 130,225

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).