Note 3 - Investments (Tables)

12 Months Ended

Sep. 30, 2023

Notes Tables

Schedule of Available-for-Sale Securities Reconciliation [Table Text Block]

	AS OF SEPTEMBER 30, 2023
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Short-term investments:
Corporate bonds	$	11,310	$	—	$	(15	)	$	11,295
U.S. treasury securities and securities of U.S. government-sponsored agency		3,622		4		—			3,626
Total	$	14,932	$	4	$	(15	)	$	14,921

	AS OF SEPTEMBER 30, 2022
	Amortized Cost		Unrealized Gains		Unrealized Losses			Estimated Fair Value
Short-term investments:
Corporate bonds	$	909	$	—	$	(15	)	$	894
Total	$	909	$	—	$	(15	)	$	894