Loans and Allowance for Loan Losses (Aging of Recorded Investment in Past Due Loans) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 6,637	$ 4,991
Current	739,838	711,290
Total Loans	746,475	716,281
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,491	2,834
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	827	713
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,319	1,444
Residential real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,716	3,939
Current	193,573	191,862
Total Loans	197,289	195,801
Residential real estate [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,903	2,088
Residential real estate [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	815	649
Residential real estate [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	998	1,202
Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,545	906
Current	355,066	344,099
Total Loans	357,611	345,005
Commercial real estate [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,306	696
Commercial real estate [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial real estate [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,239	210
Multifamily [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	80	0
Current	27,687	28,865
Total Loans	27,767	28,865
Multifamily [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	80	0
Multifamily [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Multifamily [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Current	34,313	28,347
Total Loans	34,313	28,347
Construction [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Land and land development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	27
Current	10,978	10,497
Total Loans	10,978	10,524
Land and land development [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Land and land development [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	27
Land and land development [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial business [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	122	7
Current	76,412	68,419
Total Loans	76,534	68,426
Commercial business [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43	7
Commercial business [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Commercial business [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	79	0
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	174	112
Current	41,809	39,201
Total Loans	41,983	39,313
Consumer [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	159	43
Consumer [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12	37
Consumer [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 3	$ 32