Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2023

Notes Tables

Schedule of Available-for-Sale Securities Reconciliation [Table Text Block]

	September 30, 2023						September 30, 2022
	Aggregate fair value		Amortized/Adjusted cost basis		Pretax unrealized gains		Aggregate fair value		Amortized/Adjusted cost basis		Pretax unrealized gains
Marketable securities
Common stocks	$	303,128,000	$	165,412,000	$	137,716,000	$	275,529,000	$	154,837,000	$	120,692,000

Valuation and Qualifying Accounts [Table Text Block]

Description	Balance at Beginning of Year		Additions  charged to Costs and Expenses		Accounts charged off less Recoveries			Balance at End of Year
Fiscal 2023
Allowance for doubtful accounts	$	250,000	$	8,000	$	(8,000	)	$	250,000
Fiscal 2022
Allowance for doubtful accounts	$	250,000	$	18,000	$	(18,000	)	$	250,000