Note 4 - Fair Value of Financial Instruments - Fair Value by Hierarchy (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Fair Value, Recurring [Member]
Total		$ 30,227
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total		0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total		30,227
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Total		0
Fair Value, Nonrecurring [Member]
Note receivable on sale of subsidiary		2,600
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Note receivable on sale of subsidiary		0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Note receivable on sale of subsidiary		0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Note receivable on sale of subsidiary		2,600
Corporate Debt Securities [Member] | Fair Value, Recurring [Member]
Short term investment	$ 1,997	21,849
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Short term investment	0	0
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Short term investment	1,997	21,849
Corporate Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Short term investment	$ 0	0
US Treasury and Government Short-Term Debt Securities [Member] | Fair Value, Recurring [Member]
Short term investment		8,378
US Treasury and Government Short-Term Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Short term investment		0
US Treasury and Government Short-Term Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Short term investment		8,378
US Treasury and Government Short-Term Debt Securities [Member] | Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Short term investment		$ 0