Quarterly report pursuant to Section 13 or 15(d)

Note 5 - Marketable Securities - Fair Value of Marketable Securities (Details)

v3.21.2
Note 5 - Marketable Securities - Fair Value of Marketable Securities (Details) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Total marketable securities $ 19,067 $ 20,098
Fair Value, Inputs, Level 1 [Member]    
Total marketable securities 0 0
Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 19,067 20,098
Fair Value, Inputs, Level 3 [Member]    
Total marketable securities 0 0
US Government Agencies Debt Securities [Member]    
Total marketable securities 4,247 8,924
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities 0 0
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 4,247 8,924
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities 0 0
Bank Certificates of Deposit [Member]    
Total marketable securities 0 496
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities 0 0
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 0 496
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities 0 0
Commercial Paper and Corporate Bonds [Member]    
Total marketable securities 14,820 10,678
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities 0 0
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 14,820 10,678
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities $ 0 $ 0