Loans Receivable: Financing Receivables, Summary of loans by type and risk category (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018
Loans receivable, net of allowance of $13,347 and $12,882	[2]	$ 1,122,238	[1]	$ 1,037,429	[3]
Pass
Loans receivable, net of allowance of $13,347 and $12,882	[2]	1,105,919		1,033,621
Special Mention
Loans receivable, net of allowance of $13,347 and $12,882	[2]	15,690		2,519
Substandard
Loans receivable, net of allowance of $13,347 and $12,882	[2]	629		1,289
One-to-four family residential
Loans receivable, net of allowance of $13,347 and $12,882		372,528		341,966
One-to-four family residential | Pass
Loans receivable, net of allowance of $13,347 and $12,882		371,363		339,310
One-to-four family residential | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		536		1,737
One-to-four family residential | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		629		919
Multifamily
Loans receivable, net of allowance of $13,347 and $12,882		172,915	[1],[2]	169,355	[3]
Multifamily | Pass
Loans receivable, net of allowance of $13,347 and $12,882		170,810		169,355
Multifamily | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		2,105		0
Multifamily | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		0		0
Commercial Real Estate
Loans receivable, net of allowance of $13,347 and $12,882		395,152	[1],[2]	373,798	[3]
Commercial Real Estate | Pass
Loans receivable, net of allowance of $13,347 and $12,882		394,627		372,690
Commercial Real Estate | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		525		782
Commercial Real Estate | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		0		326
Construction Land Development
Loans receivable, net of allowance of $13,347 and $12,882		113,665	[1],[2]	108,854	[3]
Construction Land Development | Pass
Loans receivable, net of allowance of $13,347 and $12,882		101,141		108,854
Construction Land Development | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		12,524		0
Construction Land Development | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		0		0
Business
Loans receivable, net of allowance of $13,347 and $12,882		37,779	[1],[2]	30,486	[3]
Business | Pass
Loans receivable, net of allowance of $13,347 and $12,882		37,779		30,486
Business | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		0		0
Business | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		0		0
Consumer
Loans receivable, net of allowance of $13,347 and $12,882		30,199	[1],[2]	12,970	[3]
Consumer | Pass
Loans receivable, net of allowance of $13,347 and $12,882		30,199		12,926
Consumer | Special Mention
Loans receivable, net of allowance of $13,347 and $12,882		0		0
Consumer | Substandard
Loans receivable, net of allowance of $13,347 and $12,882		$ 0		$ 44

[1] (1) There were no loans 90 days past due and still accruing interest at December 31, 2018.

[2] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmM4OGZhYWIzOTNiODRlMjdiYjMyMzc3NDdmYzYwZmJifFRleHRTZWxlY3Rpb246NjNERUZGNEVGRTk2MTQ3MUQ1OUExRjAyRTk4MzU1RUMM}

[3] (1) There were no loans 90 days past due and still accruing interest at December 31, 201