Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Note 7 - Fair Value Measurements and Financial Instruments - Assets Measured on a Recurring Basis (Details) - USD ($)
Sep. 30, 2021
Dec. 31, 2020
Assets, fair value $ 94,921,000 $ 122,064,000
Fair Value, Inputs, Level 1 [Member]    
Assets, fair value 0 0
Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 94,921,000 122,064,000
Fair Value, Inputs, Level 3 [Member]    
Assets, fair value 0 0
Money Market Accounts [Member]    
Assets, fair value 682,000 668,000
Money Market Accounts [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value 0 0
Money Market Accounts [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 682,000 668,000
Money Market Accounts [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value 0 0
Money Market Funds [Member]    
Assets, fair value 35,801,000 44,000,000
Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value 0 0
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 35,801,000 44,000,000
Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value 0 0
Bank Time Deposits [Member]    
Assets, fair value 18,433,000 48,397,000
Bank Time Deposits [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value 0 0
Bank Time Deposits [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 18,433,000 48,397,000
Bank Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value 0 0
Canadian Treasury Securities [Member]    
Assets, fair value 19,999 23,999,000
Canadian Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value 0 0
Canadian Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 19,999 23,999,000
Canadian Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value 0 0
US Treasury Securities [Member]    
Assets, fair value   5,000,000
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value   0
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value   5,000,000
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value   $ 0
Corporate Debt Securities [Member]    
Assets, fair value 20,006  
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value  
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 20,006  
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value