Note 3 - Income Taxes - Summary of the Difference Between Statutory Federal Income Tax Rate and Effective Rate (Details)	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Statutory federal income tax rate	21.00%	21.00%
State franchise taxes (net of federal tax benefit)	5.60%	4.50%
Effect of state rate change on beginning balance of deferred tax liabilities	(9.40%)	(0.20%)
Business meals/gifts/other permanent differences	0.60%	(0.10%)
Goodwill impairment	0.00%	(6.50%)
Dividends received deduction	(11.10%)	1.50%
Revenue recognized for book but not tax	(0.40%)	0.00%
Prior year true-up	0.00%	0.20%
Foreign tax credits	(0.40%)	0.10%
CARES Act benefits	(4.40%)	0.00%
Others	2.10%	(0.60%)
Effective tax rate	4.40%	19.90%