Loans, Allowance for Loan Losses and Impaired Loans - Schedule of Loans by Loan Class Modified in a Troubled Debt Restructuring (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2018 USD ($) TDR	Sep. 30, 2018 USD ($) TDR Contract	Sep. 30, 2017 USD ($) TDR Contract
Troubled Debt Restructuring
Number of Modifications | TDR	1	36	23
Recorded Investment | $	$ 8,418	$ 8,418	$ 5,851
Residential real estate:
Troubled Debt Restructuring
Number of Modifications		14	9
Commercial/Agricultural real estate:
Troubled Debt Restructuring
Number of Modifications		12	8
Consumer non-real estate:
Troubled Debt Restructuring
Number of Modifications		1	4
Commercial/Agricultural non-real estate:
Troubled Debt Restructuring
Number of Modifications		9	2
Originated Loans
Troubled Debt Restructuring
Number of Modifications		84	62
Recorded Investment | $	8,418	$ 8,418	$ 5,851
Originated Loans | Residential real estate:
Troubled Debt Restructuring
Number of Modifications		39	32
Recorded Investment | $	3,999	$ 3,999	$ 3,678
Originated Loans | Commercial/Agricultural real estate:
Troubled Debt Restructuring
Number of Modifications		19	8
Recorded Investment | $	2,340	$ 2,340	$ 1,890
Originated Loans | Consumer non-real estate:
Troubled Debt Restructuring
Number of Modifications		16	20
Recorded Investment | $	126	$ 126	$ 195
Originated Loans | Commercial/Agricultural non-real estate:
Troubled Debt Restructuring
Number of Modifications		10	2
Recorded Investment | $	$ 1,953	$ 1,953	$ 88