Note 3 - Short-term Investments - Summary of Short-term Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Investments, amortized cost		$ 30,170
Investments, unrealized gains		57
Investments, unrealized losses		0
Investments, fair value		30,227
Corporate Debt Securities [Member]
Investments, amortized cost	$ 1,998	21,814
Investments, unrealized gains	0	35
Investments, unrealized losses	(1)	0
Investments, fair value	$ 1,997	21,849
US Treasury and Government Short-Term Debt Securities [Member]
Investments, amortized cost		8,356
Investments, unrealized gains		22
Investments, unrealized losses		0
Investments, fair value		$ 8,378