Note 4 - Fair Value Measurements - Assets Categorized on Basis of Various Levels (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Sep. 30, 2024
Assets, fair value	$ 66,053	$ 60,957
Money Market Funds [Member]
Assets, fair value	66,042	60,946
Mutual Fund Investment [Member]
Assets, fair value	11	11
Cash and Cash Equivalents [Member]
Assets, fair value	66,042	60,946
Marketable Securities [Member]
Assets, fair value	11	11
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	66,053	60,957
Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member]
Assets, fair value	66,042	60,946
Fair Value, Inputs, Level 1 [Member] \| Mutual Fund Investment [Member]
Assets, fair value	11	11
Fair Value, Inputs, Level 1 [Member] \| Cash and Cash Equivalents [Member]
Assets, fair value	66,042	60,946
Fair Value, Inputs, Level 1 [Member] \| Marketable Securities [Member]
Assets, fair value	11	11
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Money Market Funds [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Mutual Fund Investment [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Cash and Cash Equivalents [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Marketable Securities [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Money Market Funds [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Mutual Fund Investment [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Cash and Cash Equivalents [Member]
Assets, fair value	0	0
Fair Value, Inputs, Level 3 [Member] \| Marketable Securities [Member]
Assets, fair value	$ 0	$ 0