Note 4 - Fair Value of Financial Instruments (Tables)

6 Months Ended

Mar. 31, 2024

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	As of March 31, 2024
	Quoted Prices in		Significant
	Active Markets for		Other		Significant
	Identical Assets		Observable		Unobservable
	(Level 1)		(Level 2)		(Level 3)		Totals
Short-term investments:
Corporate bonds	$	—	$	21,923	$	—	$	21,923
U.S. treasury securities and securities of U.S. government-sponsored agency				8,525				8,525
Total assets	$	—	$	30,448	$	—	$	30,448

	As of September 30, 2023
	Quoted Prices in		Significant
	Active Markets for		Other		Significant
	Identical Assets		Observable		Unobservable
	(Level 1)		(Level 2)		(Level 3)		Totals
Short-term investments:
Corporate bonds	$	—	$	11,295	$	—	$	11,295
U.S. treasury securities and securities of U.S. government-sponsored agency		—		3,626		—		3,626
Total assets	$	—	$	14,921	$	—	$	14,921