Loans Receivable - Financing Receivables, Summary of loans by type and payment activity (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	$ 1,135,050	$ 1,119,536
Property total
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	1,135,050	1,119,536
Property total | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	1,135,050	1,119,536
Property total | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
One-to-Four Family Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	436,754	385,116
One-to-Four Family Residential | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	436,754	385,116
One-to-Four Family Residential | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	135,961	130,146
Multifamily | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	135,961	130,146
Multifamily | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	412,693	419,417
Commercial real estate | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	412,693	419,417
Commercial real estate | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Construction/  Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	64,347	93,455
Construction/  Land | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	64,347	93,455
Construction/  Land | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Business
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	33,692	46,590
Business | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	33,692	46,590
Business | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	51,603	44,812
Consumer | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	51,603	44,812
Consumer | Nonperforming
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	0	0
Permanent owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	212,364	185,320
Permanent owner occupied | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	212,400	185,300
Permanent non-owner occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	224,390	199,796
Permanent non-owner occupied | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	$ 224,400	$ 199,800