Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
Note 4 - Marketable Securities - Fair Value of Marketable Securities (Details) - Fair Value, Recurring [Member]
$ in Thousands
Jun. 30, 2019
USD ($)
Commercial paper and corporate bonds $ 7,992
Fair Value, Inputs, Level 1 [Member]  
Commercial paper and corporate bonds
Fair Value, Inputs, Level 2 [Member]  
Commercial paper and corporate bonds 7,992
Fair Value, Inputs, Level 3 [Member]  
Commercial paper and corporate bonds
Commercial Paper and Corporate Bonds [Member]  
Commercial paper and corporate bonds 2,994
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 1 [Member]  
Commercial paper and corporate bonds
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 2 [Member]  
Commercial paper and corporate bonds 2,994
Commercial Paper and Corporate Bonds [Member] | Fair Value, Inputs, Level 3 [Member]  
Commercial paper and corporate bonds
US Government Agencies Debt Securities [Member]  
Commercial paper and corporate bonds 4,998
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]  
Commercial paper and corporate bonds
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]  
Commercial paper and corporate bonds 4,998
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]  
Commercial paper and corporate bonds