Loans Receivable - Additional Information (Detail)		3 Months Ended		6 Months Ended
	Dec. 27, 2020 USD ($)	Dec. 31, 2020 USD ($) Loan Property	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) Loan Property	Dec. 31, 2019 USD ($)	Jun. 30, 2020 USD ($) Loan Property
Financing Receivable Recorded Investment [Line Items]
Financing receivable TDR modified principal balance				$ 19,600,000
Loans receivable allowance for credit loss		$ 63,386,000		63,386,000
TDR charge-offs		0	$ 0	$ 0	$ 0
TDR defaults		488,000	$ 0		$ 0
Number of deferred non-TDR loans | Loan				37
Aggregate principal balance of deferred loans non-TDR loans				$ 33,200,000
Financing receivables individually analyzed loans carrying value		71,500,000		71,500,000
Financing receivables individually analyzed loans collateral dependent		58,700,000		58,700,000
Residential Mortgage [Member]
Financing Receivable Recorded Investment [Line Items]
Loans receivable allowance for credit loss		$ 12,625,000		$ 12,625,000
Number of loans in process of foreclosure | Loan		9		9		9
Mortgage loans in process of foreclosure, carrying value		$ 1,700,000		$ 1,700,000		$ 1,900,000
Residential Mortgage [Member] | Single-family Property [Member]
Financing Receivable Recorded Investment [Line Items]
Aggregate carrying value of real estate owned		$ 178,000		$ 178,000		$ 178,000
Residential Mortgage [Member] | Real Estate Acquired in Satisfaction of Debt [Member] | Single-family Property [Member]
Financing Receivable Recorded Investment [Line Items]
Number of properties held | Property		1		1		1
CARES Act [Member]
Financing Receivable Recorded Investment [Line Items]
Relief provisions	$ 900,000,000,000
Relief provision expiration date	Dec. 31, 2020
Troubled Debt Restructurings [Member]
Financing Receivable Recorded Investment [Line Items]
Loans receivable allowance for credit loss		$ 209,000		$ 209,000		$ 8,000