Note 12 - Financial Instruments and Fair Value Disclosures - Financial Assets or Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
Dec. 31, 2021
Dec. 31, 2020
Statement Line Items [Line Items]    
Financial assets $ 57,927 $ 105,959
Level 1 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 57,927 105,959
Level 2 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 0 0
Level 3 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 0 0
Cash [member]    
Statement Line Items [Line Items]    
Financial assets 56,748 94,008
Cash [member] | Level 1 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 56,748 94,008
Cash [member] | Level 2 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 0 0
Cash [member] | Level 3 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets 0 0
Investments [member]    
Statement Line Items [Line Items]    
Financial assets [1] 1,179 11,951
Investments [member] | Level 1 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets [1] 1,179 11,951
Investments [member] | Level 2 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets [1] 0 0
Investments [member] | Level 3 of fair value hierarchy [member]    
Statement Line Items [Line Items]    
Financial assets [1] $ 0 $ 0
[1] The fair value of equity securities quoted in active markets, is determined based on a market approach reflecting the closing price of each particular security as at the statement of financial position date. The closing price is a quoted market price obtained from the exchange that is the principal active market for the particular security, and therefore equity securities are classified within Level 1 of the fair value hierarchy. The fair values of equity securities and warrants that are not quoted in active markets are valued based on quoted prices of similar instruments in active markets or using valuation techniques where all inputs are directly or indirectly observable from market data and are classified within Level 2 of the fair value hierarchy.