Loans Receivable and Allowance for Credit Losses - Aging of Loans and Accrual Status by Class (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Financing Receivable, Recorded Investment, Past Due
Total Loans	$ 1,309,712,000	$ 1,308,552,000
Nonaccrual Loans	2,205,000	2,260,000
Loans 90 Days or More Past Due and Still Accruing	0	0
One- to four-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	1,273,911,000	1,275,615,000
Nonaccrual Loans	2,026,000	2,079,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Multi-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	5,597,000	5,848,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Construction, Commercial and Other Mortgage Loans
Financing Receivable, Recorded Investment, Past Due
Total Loans	12,493,000	11,570,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Home equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due
Total Loans	9,221,000	7,060,000
Nonaccrual Loans	9,000	11,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Loans on Deposit Accounts
Financing Receivable, Recorded Investment, Past Due
Total Loans	180,000	196,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	8,310,000	8,263,000
Nonaccrual Loans	170,000	170,000
Loans 90 Days or More Past Due and Still Accruing	0	0
Not Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans	1,309,347,000	1,307,893,000
Not Past Due | One- to four-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	1,273,726,000	1,274,960,000
Not Past Due | Multi-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	5,597,000	5,848,000
Not Past Due | Construction, Commercial and Other Mortgage Loans
Financing Receivable, Recorded Investment, Past Due
Total Loans	12,493,000	11,570,000
Not Past Due | Home equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due
Total Loans	9,221,000	7,060,000
Not Past Due | Loans on Deposit Accounts
Financing Receivable, Recorded Investment, Past Due
Total Loans	180,000	196,000
Not Past Due | Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	8,130,000	8,259,000
Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans	365,000	659,000
Past Due | One- to four-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	185,000	655,000
Past Due | Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	180,000	4,000
30 - 59 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans	107,000	432,000
30 - 59 Days Past Due | One- to four-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	98,000	428,000
30 - 59 Days Past Due | Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	9,000	4,000
60 - 89 Days Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans	170,000
60 - 89 Days Past Due | Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	170,000
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due
Total Loans	88,000	227,000
90 Days or More Past Due | One- to four-family residential
Financing Receivable, Recorded Investment, Past Due
Total Loans	87,000	$ 227,000
90 Days or More Past Due | Consumer and other
Financing Receivable, Recorded Investment, Past Due
Total Loans	$ 1,000