Loans Receivable: Financing Receivables, Summary of loans by type and risk category (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	$ 1,182,159	$ 1,119,536
One-to-four family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	475,836	385,116
Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	126,895	130,146
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	407,882	419,417
Construction Land Development
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	78,120	93,455
Business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	31,371	46,590
Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	62,055	44,812
Pass, grade 1-4
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	1,110,622	1,042,837
Pass, grade 1-4 | One-to-four family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	473,700	383,276
Pass, grade 1-4 | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	122,972	126,149
Pass, grade 1-4 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	342,827	351,241
Pass, grade 1-4 | Construction Land Development
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	78,120	91,202
Pass, grade 1-4 | Business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	31,371	46,590
Pass, grade 1-4 | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	61,632	44,379
Pass, Grade 5
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	18,276	30,213
Pass, Grade 5 | One-to-four family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	1,113	911
Pass, Grade 5 | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	2,291	3,997
Pass, Grade 5 | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	14,845	23,019
Pass, Grade 5 | Construction Land Development
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	2,253
Pass, Grade 5 | Business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Pass, Grade 5 | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	27	33
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	5,894	12,277
Special Mention | One-to-four family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	1,023	929
Special Mention | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Special Mention | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	4,668	11,127
Special Mention | Construction Land Development
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Special Mention | Business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Special Mention | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	203	221
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	47,367	34,209
Substandard | One-to-four family residential
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Substandard | Multifamily
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	1,632	0
Substandard | Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	45,542	34,030
Substandard | Construction Land Development
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Substandard | Business
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	0	0
Substandard | Consumer
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance	$ 193	$ 179