Note 3 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Income Tax Expense (Benefit), Total	$ (26,925,000)	$ 40,150,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	(102,549,000)	153,050,000
Effective Income Tax Rate Reconciliation, Unrealized Gains (Losses) on Marketable Securities, Amount	32,840,000	27,938,000
Effective Income Tax Rate Reconciliation, Benefit for the Dividends Received Deduction and Other Permanent Book and Tax Differences, Amount	340,000
Effective Income Tax Rate Reconciliation, Realized Gains on Marketable Securities, Amount	3,790,000	$ 10,952,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	1,735,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	$ 730,000
Effective Income Tax Rate Reconciliation, Percent, Total	26.30%	26.20%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount		$ 1,260,000
Domestic Tax Authority [Member]
Open Tax Year	2019 2020 2021 2022
State and Local Jurisdiction [Member]
Open Tax Year	2018 2019 2020 2021 2022
State and Local Jurisdiction [Member] | California Franchise Tax Board [Member]
Operating Loss Carryforwards, Total	$ 5,500,000