Note 3 - Income Taxes - Deferred Income Taxes (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019
Deferred tax assets attributable to:
Accrued liabilities, including supplemental compensation and vacation pay accrual	$ 415,000	$ 178,000
Impairment losses on investments	1,016,000	2,201,000
Bad debt reserves not yet deductible	55,000	41,000
Depreciation and amortization	3,482,000	3,999,000
Deferred revenues	913,000	885,000
Goodwill	590,000	677,000
Net operating losses	4,768,000	5,195,000
Credits and other	432,000	456,000
Total deferred tax assets	11,671,000	13,632,000
Deferred tax liabilities attributable to:
Unrealized gains on investments	(35,870,000)	(37,241,000)
Net deferred income taxes	$ (24,199,000)	$ (23,609,000)