Note 2 - Summary of Significant Accounting Policies (Tables)

12 Months Ended

Sep. 30, 2020

Notes Tables

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

	September 30, 2020						September 30, 2019
	Aggregate fair value		Amortized/ Adjusted cost basis		Pretax unrealized gains		Aggregate fair value		Amortized/ Adjusted cost basis		Pretax unrealized gains
Marketable securities
Common stocks	$	179,368,000	$	41,775,000	$	137,593,000	$	194,581,000	$	53,889,000	$	140,692,000

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 2020
Allowance for doubtful accounts	$	200,000	$	116,000	$	(66,000	)	$	250,000
Fiscal 2019
Allowance for doubtful accounts	$	200,000	$	8,000	$	(8,000	)	$	200,000