Quarterly report pursuant to Section 13 or 15(d)

Note 4 - Marketable Securities - Fair Value of Marketable Securities (Details)

v3.20.1
Note 4 - Marketable Securities - Fair Value of Marketable Securities (Details) - Fair Value, Recurring [Member] - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
Total marketable securities $ 9,348 $ 3,995
Fair Value, Inputs, Level 1 [Member]    
Total marketable securities
Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 9,348 3,995
Fair Value, Inputs, Level 3 [Member]    
Total marketable securities
US Government Agencies Debt Securities [Member]    
Total marketable securities 6,352 1,998
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 6,352 1,998
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities
Bank Certificates of Deposit [Member]    
Total marketable securities 1,998
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 1,998
Bank Certificates of Deposit [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities
Commercial Paper and Corporate Bonds [Member]    
Total marketable securities 998 1,997
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 1 [Member]    
Total marketable securities
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]    
Total marketable securities 998 1,997
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 3 [Member]    
Total marketable securities