Note 4 - Fair Value Measurements - Assets Categorized on Basis of Various Levels (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Assets, fair value	$ 65,359	$ 60,957
Money Market Funds [Member]
Assets, fair value	65,348	60,946
Mutual Fund Investment [Member]
Assets, fair value	11	11
Cash and Cash Equivalents [Member]
Assets, fair value	65,348	60,946
Marketable Securities [Member]
Assets, fair value	11	11
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	65,359	60,957
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets, fair value	65,348	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	65,348	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