Note 4 - Investments - Securities in a Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Fair value unrealized loss, less than 12 months	$ 19,659	$ 19,719
Gross unrealized loss, less than 12 months	(29)	(39)
Fair value unrealized loss, greater than 12 months	5,407	6,736
Gross unrealized loss, greater than 12 months	(118)	(262)
US Treasury Securities [Member]
Fair value unrealized loss, less than 12 months	19,659	19,719
Gross unrealized loss, less than 12 months	(29)	(39)
Fair value unrealized loss, greater than 12 months	5,166	6,500
Gross unrealized loss, greater than 12 months	(111)	(250)
Certificates of Deposit [Member]
Fair value unrealized loss, less than 12 months	0	0
Gross unrealized loss, less than 12 months	0	0
Fair value unrealized loss, greater than 12 months	241	236
Gross unrealized loss, greater than 12 months	$ (7)	$ (12)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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