Note 9 - Income Taxes (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Tax Expense (Benefit), Total	$ (3,665,000)	$ 15,200,000	$ (9,735,000)	$ 40,115,000
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total	$ (13,527,000)	$ 57,773,000	(40,532,000)	154,434,000
Effective Income Tax Rate Reconciliation, Unrealized Gains (Losses) on Marketable Securities, Amount			(15,425,000)	34,405,000
Effective Income Tax Rate Reconciliation, Benefit for the Dividends Received Deduction and Other Permanent Book and Tax Differences, Amount			250,000
Effective Income Tax Rate Reconciliation, Realized Gains on Marketable Securities, Amount			3,850,000	$ 4,821,000
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount			500,000
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount			$ 1,590,000
Effective Income Tax Rate Reconciliation, Percent, Total			24.00%	26.00%
Effective Income Tax Rate Reconciliation before Realized and Unrealized Gains of Marketable Securities, Percent				21.32%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%
Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount				$ 896,000
Effective Income Tax Rate Reconciliation, Tax Contingency, State and Local, Amount				$ 7,000
Domestic Tax Authority [Member]
Open Tax Year			2018
State and Local Jurisdiction [Member]
Open Tax Year			2017