Note 9 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Income Tax Expense (Benefit)	$ 5,205,000	$ 3,835,000	$ 8,330,000	$ 9,935,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ 20,620,000	$ 13,268,000	36,360,000	37,195,000
Effective Income Tax Rate Reconciliation, Realized Gains on Marketable Securities, Amount			3,660,000	110,000
Effective Income Tax Rate Reconciliation, Unrealized Gains (Losses) on Marketable Securities, Amount			5,180,000	8,770,000
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount			40,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount			480,000	1,005,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount			210,000	210,000
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount			$ 820,000	$ 160,000
Effective Income Tax Rate Reconciliation, Percent			22.90%	26.70%
Domestic Tax Jurisdiction [Member]
Open Tax Year			2021 2022 2023 2024
State and Local Jurisdiction [Member]
Open Tax Year			2020 2021 2022 2023 2024