Employee Benefit Plans (Summary of Fair Value Classifications of Benefit Plan Assets ) (Details) - USD ($)	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 37,657,631	$ 33,586,671	$ 28,184,697
Pension Plan | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,665,698	1,943,321
Pension Plan | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	35,991,933	31,643,350
Pension Plan | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	339,287	371,780
Pension Plan | Cash | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	339,287	371,780
Pension Plan | Cash | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Cash | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Bonds, Liability Driven Investment
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	26,038,966	19,702,561
Pension Plan | Common and Collective Trust and Pooled Funds, Bonds, Liability Driven Investment | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Bonds, Liability Driven Investment | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	26,038,966	19,702,561
Pension Plan | Common and Collective Trust and Pooled Funds, Bonds, Liability Driven Investment | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	3,462,841	4,069,197
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Growth | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Growth | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	3,462,841	4,069,197
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Growth | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	3,351,694	4,055,518
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	3,351,694	4,055,518
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Large Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Small/Mid Cap Core
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,665,005	2,032,084
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Small/Mid Cap Core | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Small/Mid Cap Core | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,665,005	2,032,084
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Domestic Small/Mid Cap Core | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Foreign Large Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,473,427	1,783,990
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Foreign Large Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Foreign Large Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,473,427	1,783,990
Pension Plan | Common and Collective Trust and Pooled Funds, Equities, Foreign Large Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,047,274	1,227,981
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,047,274	1,227,981
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	279,137	343,560
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	279,137	343,560
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Pension Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	14,116,253	13,082,610	$ 12,924,957
Postretirement Plan | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	14,095,104	13,054,626
Postretirement Plan | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	21,149	27,984
Postretirement Plan | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	73,908	66,860
Postretirement Plan | Cash | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	73,908	66,860
Postretirement Plan | Cash | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Cash | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Bonds, Domestic Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	6,163,808	5,987,248
Postretirement Plan | Mutual Funds, Bonds, Domestic Fixed Income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	6,163,808	5,987,248
Postretirement Plan | Mutual Funds, Bonds, Domestic Fixed Income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Bonds, Domestic Fixed Income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Bonds, Foreign Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	638,709	611,196
Postretirement Plan | Mutual Funds, Bonds, Foreign Fixed Income | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	638,709	611,196
Postretirement Plan | Mutual Funds, Bonds, Foreign Fixed Income | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Bonds, Foreign Fixed Income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	2,197,839	1,909,836
Postretirement Plan | Mutual Funds, Equities, Domestic Large Cap Growth | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	2,197,839	1,909,836
Postretirement Plan | Mutual Funds, Equities, Domestic Large Cap Growth | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Large Cap Growth | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, , Domestic Large Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	2,119,433	1,931,615
Postretirement Plan | Mutual Funds, Equities, , Domestic Large Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	2,119,433	1,931,615
Postretirement Plan | Mutual Funds, Equities, , Domestic Large Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, , Domestic Large Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	262,726	210,251
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Growth | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	262,726	210,251
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Growth | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Growth | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	235,216	214,034
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	235,216	214,034
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Core
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	552,607	464,526
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Core | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	552,607	464,526
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Core | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Domestic Small Mid Cap Core | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	548,967	489,286
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	548,967	489,286
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Growth | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,224,420	1,098,992
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	1,224,420	1,098,992
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Value | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Core
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	77,471	70,782
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Core | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	77,471	70,782
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Core | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Equities, Foreign Large Cap Core | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	21,149	27,984
Postretirement Plan | Mutual Funds, Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	0	0
Postretirement Plan | Mutual Funds, Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	21,149	27,984
Postretirement Plan | Mutual Funds, Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of benefit plan assets	$ 0	$ 0