Note 3 - Cash and Investments - Amortized Cost and Fair Value of Short-Term Investments (Details) $ in Thousands	Sep. 30, 2022 USD ($)
U.S. treasury securities, AC	$ 10,677
U.S. treasury securities, CV	10,677
U.S. treasury securities, unrealized losses	3
U.S. treasury securities, FV	10,674
US Treasury Securities [Member]
U.S. treasury securities, AC	10,677
U.S. treasury securities, CV	10,677
U.S. treasury securities, unrealized losses	3
U.S. treasury securities, FV	$ 10,674