Note 3 - Cash and Investments - Amortized Cost and Fair Value of Short-Term Investments (Details) $ in Thousands	Mar. 31, 2023 USD ($)
U.S. treasury securities, AC	$ 26,211
U.S. treasury securities, CV	26,211
U.S. treasury securities, unrealized losses	0
U.S. treasury securities, FV	26,224
US Treasury Securities [Member]
U.S. treasury securities, AC	26,211
U.S. treasury securities, CV	26,211
U.S. treasury securities, unrealized losses	0
U.S. treasury securities, FV	$ 26,224