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Loans Receivable - Summary of Balance in Allowance for Loan Losses and Recorded investment in Loans by Portfolio Segment, and Based on Impairment Method (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	$ 8,670		$ 8,059
Loans, Collectively Evaluated for Impairment	1,284,017		1,227,732
Total	1,294,081		1,237,522
Allowance for loan losses, Individually Evaluated for Impairment	118		121
Allowance for loan losses, Collectively Evaluated for Impairment	8,593		7,760
Allowance for loan losses, Total	8,711	$ 8,429	7,881	$ 7,865	$ 8,677	$ 8,639
Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Acquired With Deteriorated Credit Quality	1,394		1,731
Allowance for loan losses, Acquired With Deteriorated Credit Quality	0		0
Residential Mortgages [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	1,740		2,356
Loans, Collectively Evaluated for Impairment	213,274		221,229
Total	215,431		224,305
Allowance for loan losses, Individually Evaluated for Impairment	110		113
Allowance for loan losses, Collectively Evaluated for Impairment	214		224
Allowance for loan losses, Total	324	319	337	332	334	373
Residential Mortgages [Member] \| Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Acquired With Deteriorated Credit Quality	417		720
Commercial Mortgages [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	4,790		3,582
Loans, Collectively Evaluated for Impairment	891,768		822,154
Total	897,424		826,624
Allowance for loan losses, Collectively Evaluated for Impairment	7,059		6,435
Allowance for loan losses, Total	7,059	6,853	6,435	6,518	6,872	6,913
Commercial Mortgages [Member] \| Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Acquired With Deteriorated Credit Quality	866		888
Construction [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	1,113
Loans, Collectively Evaluated for Impairment	15,781		10,151
Total	16,894		10,151
Allowance for loan losses, Collectively Evaluated for Impairment	166		102
Allowance for loan losses, Total	166	129	102	102	205	165
Commercial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	652		1,707
Loans, Collectively Evaluated for Impairment	140,775		148,951
Total	141,427		150,658
Allowance for loan losses, Collectively Evaluated for Impairment	1,109		948
Allowance for loan losses, Total	1,109	1,067	948	848	1,201	1,124
Home Equity Lines Of Credit [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Individually Evaluated for Impairment	375		414
Loans, Collectively Evaluated for Impairment	22,071		24,902
Total	22,557		25,439
Allowance for loan losses, Individually Evaluated for Impairment	8		8
Allowance for loan losses, Collectively Evaluated for Impairment	41		46
Allowance for loan losses, Total	49	51	54	62	61	$ 60
Home Equity Lines Of Credit [Member] \| Acquired with Deteriorated Credit Quality [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Acquired With Deteriorated Credit Quality	111		123
Consumer and Overdrafts [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans, Collectively Evaluated for Impairment	348		345
Total	348		345
Allowance for loan losses, Collectively Evaluated for Impairment	4		5
Allowance for loan losses, Total	$ 4	$ 10	$ 5	$ 3	$ 4