Note 8 - Employee Benefit Plans (Details Textual)	9 Months Ended
	Jun. 30, 2018
Supplemental Employee Retirement Plan [Member]
Defined Benefit Plan Employment Term	30 years
Supplemental Retirement Benefit Period	15 years
Defined Benefit Plan Percent of Highest Average Salary Base	50.00%
Defined Benefit Plan Number of Years in Average Annual Base Salary	5 years
Defined Benefit Plan Number of Years Preceding Retirement for Average Annual Base Salary Calculation	10 years
Reduced SERP [Member]
Defined Benefit Plan Retirement Age	65
Defined Benefit Plan, Reduction for Each Month	0.0028%
Reduced SERP [Member] | Minimum [Member]
Defined Benefit Plan Employment Term	10 years