Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2022

Notes Tables

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

	September 30, 2022						September 30, 2021
	Aggregate fair value		Amortized/ Adjusted cost basis		Pretax unrealized gains		Aggregate fair value		Amortized/ Adjusted cost basis		Pretax unrealized gains
Marketable securities
Common stocks	$	275,529,000	$	154,837,000	$	120,692,000	$	347,573,000	$	103,480,000	$	244,093,000

Valuation and Qualifying Accounts [Table Text Block]

Description	Balance at Beginning of Year		Additions (Reductions) charged to Costs and Expenses			Accounts charged off less Recoveries			Balance at End of Year
Fiscal 2022
Allowance for doubtful accounts	$	250,000	$	18,000		$	(18,000	)	$	250,000
Fiscal 2021
Allowance for doubtful accounts	$	250,000	$	(3,000	)	$	3,000		$	250,000