Loans and Allowance for Loan Losses (Recorded Investment in Loans by Risk Category) (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 574,593	$ 527,184
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	557,612	514,489
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,194	584
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	10,643	12,007
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	144	104
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	174,181	179,027
Residential Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	167,238	173,477
Residential Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	421	459
Residential Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	6,380	5,002
Residential Real Estate [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	142	89
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	255,618	217,716
Commercial Real Estate [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	249,223	211,247
Commercial Real Estate [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,133	0
Commercial Real Estate [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	3,262	6,469
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	18,714	18,452
Multifamily [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	16,180	18,452
Multifamily [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2,534	0
Multifamily [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
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	33,163	30,306
Construction [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	32,624	30,206
Construction [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	95	100
Construction [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	444	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	9,329	11,164
Land and Land Development [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	9,015	10,924
Land and Land Development [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	0
Land and Land Development [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	314	240
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	52,794	42,147
Commercial Business [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	52,700	41,986
Commercial Business [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	0	25
Commercial Business [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	94	136
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	30,794	28,372
Consumer [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	30,632	28,197
Consumer [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	11	0
Consumer [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	149	160
Consumer [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	2	15
Consumer [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total Loans	$ 0	$ 0