Quarterly report pursuant to Section 13 or 15(d)

Note 7 - Fair Value Measurements and Financial Instruments - Assets Measured on a Recurring Basis (Details)

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Note 7 - Fair Value Measurements and Financial Instruments - Assets Measured on a Recurring Basis (Details) - USD ($)
$ in Thousands
Mar. 31, 2023
Dec. 31, 2022
Assets, Fair Value Disclosure $ 34,588 $ 46,363
Level 1 [Member]    
Assets, Fair Value Disclosure 0 0
Level 2 [Member]    
Assets, Fair Value Disclosure 34,588 46,363
Level 3 [Member]    
Assets, Fair Value Disclosure 0 0
Money Market Accounts [Member]    
Assets, Fair Value Disclosure   165
Money Market Accounts [Member] | Level 1 [Member]    
Assets, Fair Value Disclosure   0
Money Market Accounts [Member] | Level 2 [Member]    
Assets, Fair Value Disclosure   165
Money Market Accounts [Member] | Level 3 [Member]    
Assets, Fair Value Disclosure   0
Money Market Funds [Member]    
Assets, Fair Value Disclosure 14,126 22,343
Money Market Funds [Member] | Level 1 [Member]    
Assets, Fair Value Disclosure 0 0
Money Market Funds [Member] | Level 2 [Member]    
Assets, Fair Value Disclosure 14,126 22,343
Money Market Funds [Member] | Level 3 [Member]    
Assets, Fair Value Disclosure 0 0
High Interest Savings Account [Member]    
Assets, Fair Value Disclosure 1,537 13,866
High Interest Savings Account [Member] | Level 1 [Member]    
Assets, Fair Value Disclosure 0 0
High Interest Savings Account [Member] | Level 2 [Member]    
Assets, Fair Value Disclosure 1,537 13,866
High Interest Savings Account [Member] | Level 3 [Member]    
Assets, Fair Value Disclosure 0 0
United States Treasury Bills [Member]    
Assets, Fair Value Disclosure   9,989
Cash and cash equivalents 5,967  
Short term investments 9,985  
United States Treasury Bills [Member] | Level 1 [Member]    
Assets, Fair Value Disclosure   0
Cash and cash equivalents 0  
Short term investments 0  
United States Treasury Bills [Member] | Level 2 [Member]    
Assets, Fair Value Disclosure   9,989
Cash and cash equivalents 5,967  
Short term investments 9,985  
United States Treasury Bills [Member] | Level 3 [Member]    
Assets, Fair Value Disclosure   $ 0
Cash and cash equivalents 0  
Short term investments  
Commercial Note [Member]    
Assets, Fair Value Disclosure 2,973  
Commercial Note [Member] | Level 1 [Member]    
Assets, Fair Value Disclosure 0  
Commercial Note [Member] | Level 2 [Member]    
Assets, Fair Value Disclosure 2,973  
Commercial Note [Member] | Level 3 [Member]    
Assets, Fair Value Disclosure $ 0