Loans and Allowance for Loan Losses (Recorded Investment in Loans by Risk Category) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 746,475	$ 716,281
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	725,771	701,230
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,179	309
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	15,455	14,668
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	70	74
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	197,289	195,801
Residential Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	192,749	190,647
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	19
Residential Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	4,470	5,061
Residential Real Estate [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	70	74
Residential Real Estate [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	357,611	345,005
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	344,399	338,256
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	5,096	0
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	8,116	6,749
Commercial Real Estate [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Commercial Real Estate [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Multifamily [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,767	28,865
Multifamily [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	27,275	28,365
Multifamily [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Multifamily [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	492	500
Multifamily [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Multifamily [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	34,313	28,347
Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	34,313	28,347
Construction [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Construction [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Construction [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Construction [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Land and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	10,978	10,524
Land and Land Development [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	10,895	10,207
Land and Land Development [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	83	290
Land and Land Development [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	27
Land and Land Development [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Land and Land Development [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Commercial Business [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	76,534	68,426
Commercial Business [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	74,208	66,162
Commercial Business [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Commercial Business [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,326	2,264
Commercial Business [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Commercial Business [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	41,983	39,313
Consumer [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	41,932	39,246
Consumer [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Consumer [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	51	67
Consumer [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Consumer [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 0	$ 0