Loans Receivable - Aging of Recorded Investment in Past Due Loans (Detail) - USD ($) $ in Thousands		Mar. 31, 2022	Jun. 30, 2021
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		$ 4,490	$ 2,681
Total		1,294,081	1,237,522
30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		109	720
60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		11	221
90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4,370	1,740
Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	1,289,591	1,234,841
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		869	1,272
Total		215,431	224,305
Residential Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			198
Residential Mortgages [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			126
Residential Mortgages [Member] | 90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		869	948
Residential Mortgages [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	214,562	223,033
Commercial Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,631	864
Total		897,424	826,624
Commercial Mortgages [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			453
Commercial Mortgages [Member] | 90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,631	411
Commercial Mortgages [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	895,793	825,760
Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,113
Total		16,894	10,151
Construction [Member] | 90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,113
Construction [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	15,781	10,151
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		423	145
Total		141,427	150,658
Commercial Loans [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		12	69
Commercial Loans [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		11	76
Commercial Loans [Member] | 90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		400
Commercial Loans [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	141,004	150,513
Home Equity Lines Of Credit [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		454	400
Total		22,557	25,439
Home Equity Lines Of Credit [Member] | 30-59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		97
Home Equity Lines Of Credit [Member] | 60-89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due			19
Home Equity Lines Of Credit [Member] | 90 Days or More Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		357	381
Home Equity Lines Of Credit [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	22,103	25,039
Consumer and Overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total		348	345
Consumer and Overdrafts [Member] | Current
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[1]	$ 348	$ 345

[1] As of March 31, 2022 and June 30, 2021, loans on a COVID-19-related payment deferral are considered current.