Note 2 - Fair Value Measurements - Assets Categorized on Basis of Various Levels (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Assets, fair value	$ 60,957	$ 59,392
Money Market Funds [Member]
Assets, fair value	60,946	59,382
Mutual Fund Investment [Member]
Assets, fair value	11	10
Cash and Cash Equivalents [Member]
Assets, fair value	60,946	59,382
Marketable Securities [Member]
Assets, fair value	11	10
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	60,957	59,392
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets, fair value	60,946	59,382
Fair Value, Inputs, Level 1 [Member] | Mutual Fund Investment [Member]
Assets, fair value	11	10
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Assets, fair value	60,946	59,382
Fair Value, Inputs, Level 1 [Member] | Marketable Securities [Member]
Assets, fair value	11	10
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