Loans and Allowance for Loan Losses (Troubled Debt Restructurings) (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2017 USD ($) Number	Jun. 30, 2016 USD ($) Number	Jun. 30, 2017 USD ($) Number	Jun. 30, 2016 USD ($) Number
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Number of Loans | Number	2	2	4	9
Pre-Modification Principal Balance	$ 124	$ 191	$ 606	$ 461
Post-Modification Principal Balance	$ 124	$ 228	$ 609	$ 594
Residential real estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Number of Loans | Number	1		2	5
Pre-Modification Principal Balance	$ 21		$ 472	$ 181
Post-Modification Principal Balance	$ 21		$ 474	$ 247
Commercial real estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Number of Loans | Number		1		1
Pre-Modification Principal Balance		$ 94		$ 94
Post-Modification Principal Balance		$ 131		$ 131
Commercial Business [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Number of Loans | Number	1	1	1	3
Pre-Modification Principal Balance	$ 103	$ 97	$ 103	$ 186
Post-Modification Principal Balance	$ 103	$ 97	$ 103	$ 216
Land and land development [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Number of Loans | Number			1
Pre-Modification Principal Balance			$ 31
Post-Modification Principal Balance			$ 32