Loans - Credit quality indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 458,512	$ 465,629
Residential and Consumer Loan
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	210,777	224,599
Residential and Consumer Loan | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	206,723	220,362
Residential and Consumer Loan | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,054	4,237
Commercial Loan Total
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	247,735	241,030
Commercial Loan Total | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	243,848	237,556
Commercial Loan Total | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,386	2,410
Commercial Loan Total | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	1,501	1,064
Residential real estate | 1-4 Family
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	162,822	173,306
Residential real estate | Home equity and HELOCs
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	34,546	37,222
Residential real estate | Construction Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,734	10,841
Residential real estate | Residential and Consumer Loan | 1-4 Family
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	162,822	173,306
Residential real estate | Residential and Consumer Loan | 1-4 Family | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	159,295	169,532
Residential real estate | Residential and Consumer Loan | 1-4 Family | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	3,527	3,774
Residential real estate | Residential and Consumer Loan | Home equity and HELOCs
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	34,546	37,222
Residential real estate | Residential and Consumer Loan | Home equity and HELOCs | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	34,136	36,877
Residential real estate | Residential and Consumer Loan | Home equity and HELOCs | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	410	345
Residential real estate | Residential and Consumer Loan | Construction Residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,734	10,841
Residential real estate | Residential and Consumer Loan | Construction Residential | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,734	10,841
Commercial real estate | 1 - 4 family investor
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	120,620	120,581
Commercial real estate | 1 - 4 family investor | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	118,090	118,175
Commercial real estate | 1 - 4 family investor | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,054	2,054
Commercial real estate | 1 - 4 family investor | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	476	352
Commercial real estate | Multi-family (five or more)
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	11,367	12,315
Commercial real estate | Multi-family (five or more) | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	10,864	12,139
Commercial real estate | Multi-family (five or more) | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	503	176
Commercial real estate | Commercial non-residential
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	104,759	96,612
Commercial real estate | Commercial non-residential | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	103,905	95,720
Commercial real estate | Commercial non-residential | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	332	356
Commercial real estate | Commercial non-residential | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	522	536
Commercial real estate | Construction and Land
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	6,474	6,377
Commercial real estate | Construction and Land | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	6,474	6,377
Commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,515	5,145
Commercial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	4,515	5,145
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,675	3,230
Consumer | Residential and Consumer Loan
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,675	3,230
Consumer | Residential and Consumer Loan | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	2,558	3,112
Consumer | Residential and Consumer Loan | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Total Loans	$ 117	$ 118