Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Expected amount of AOCI recognized in net periodic benefit costs		$ 80,000
Expected amount of deferred regulatory assets to be recognized in net periodic benefit costs		$ 577,000
First Portion Match
Defined Benefit Plan Disclosure [Line Items]
Employers percentage match of employees match percentage		100.00%
Percentage of employee's gross pay that is matched by the employer		4.00%
Second Portion Match
Defined Benefit Plan Disclosure [Line Items]
Employers percentage match of employees match percentage		50.00%
Percentage of employee's gross pay that is matched by the employer		2.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Employee contribution percent		1.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Employee contribution percent		50.00%
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Years until benefits are fully vested		5 years
Plan assets, target allocation, percentage		30.00%	40.00%
Expected long-term rate of return on plan assets		5.50%	5.50%
Expected employer contributions in next fiscal year		$ 500,000
Pension Plan | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	5.40%
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Minimum service requirement for postretirement benefit vesting		10 years
Retirement age requirement, postretirement plan		55 years
Expected long-term rate of return on plan assets		4.26%	4.30%
Expected employer contributions in next fiscal year		$ 400,000