Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Fair Value Measurements and Financial Instruments - Assets Measured on a Recurring Basis (Details)

v3.20.2
Note 6 - Fair Value Measurements and Financial Instruments - Assets Measured on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Sep. 30, 2020
Dec. 31, 2019
Assets, fair value $ 129,362 $ 95,960
Fair Value, Inputs, Level 1 [Member]    
Assets, fair value
Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 129,362 95,960
Fair Value, Inputs, Level 3 [Member]    
Assets, fair value
Bank Time Deposits [Member]    
Assets, fair value 96,365 2,989
Bank Time Deposits [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value
Bank Time Deposits [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 96,365 2,989
Bank Time Deposits [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value
Corporate Debt Securities [Member]    
Assets, fair value 9,000 6,235
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 9,000 6,235
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value
US Treasury Securities [Member]    
Assets, fair value 23,997  
US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value  
US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value 23,997  
US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value  
Canadian Provincial Promissory Notes [Member]    
Assets, fair value   5,493
Canadian Provincial Promissory Notes [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value  
Canadian Provincial Promissory Notes [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value   5,493
Canadian Provincial Promissory Notes [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value  
Investments [Member]    
Assets, fair value   81,243
Investments [Member] | Fair Value, Inputs, Level 1 [Member]    
Assets, fair value  
Investments [Member] | Fair Value, Inputs, Level 2 [Member]    
Assets, fair value   81,243
Investments [Member] | Fair Value, Inputs, Level 3 [Member]    
Assets, fair value