Loans Receivable: Financing Receivables, Summary of loans by type and risk category (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, after Allowance for Credit Loss	$ 1,066,301,000	$ 1,037,429,000
One to four family residential
Financing Receivable, after Allowance for Credit Loss	361,256,000	341,966,000
Multifamily
Financing Receivable, after Allowance for Credit Loss	161,460,000	169,355,000
Commercial Real Estate
Financing Receivable, after Allowance for Credit Loss	384,202,000	373,798,000
Construction Land Development [Member]
Financing Receivable, after Allowance for Credit Loss	105,134,000	108,854,000
Business [Member]
Financing Receivable, after Allowance for Credit Loss	36,358,000	30,486,000
Consumer
Financing Receivable, after Allowance for Credit Loss	17,891,000	12,970,000
Property total
Financing Receivable, after Allowance for Credit Loss	1,066,301,000	1,037,429,000
One-to-four family, residential, owner occupied
Financing Receivable, after Allowance for Credit Loss	201,989,000	194,141,000
One to four family residential non owner occupied
Financing Receivable, after Allowance for Credit Loss	159,267,000	147,825,000
Performing Financing Receivable | One to four family residential
Financing Receivable, after Allowance for Credit Loss	361,153,000	341,584,000
Performing Financing Receivable | Multifamily
Financing Receivable, after Allowance for Credit Loss	161,460,000	169,355,000
Performing Financing Receivable | Commercial Real Estate
Financing Receivable, after Allowance for Credit Loss	384,202,000	373,472,000
Performing Financing Receivable | Construction Land Development [Member]
Financing Receivable, after Allowance for Credit Loss	105,134,000	108,854,000
Performing Financing Receivable | Business [Member]
Financing Receivable, after Allowance for Credit Loss	36,358,000	30,486,000
Performing Financing Receivable | Consumer
Financing Receivable, after Allowance for Credit Loss	17,848,000	12,926,000
Performing Financing Receivable | Property total
Financing Receivable, after Allowance for Credit Loss	1,066,155,000	1,036,677,000
Performing Financing Receivable | One-to-four family, residential, owner occupied
Financing Receivable, after Allowance for Credit Loss	201,900,000	193,800,000
Performing Financing Receivable | One to four family residential non owner occupied
Financing Receivable, after Allowance for Credit Loss	159,200,000	147,800,000
Nonperforming Financing Receivable | One to four family residential
Financing Receivable, after Allowance for Credit Loss	103,000	382,000
Nonperforming Financing Receivable | Multifamily
Financing Receivable, after Allowance for Credit Loss	0	0
Nonperforming Financing Receivable | Commercial Real Estate
Financing Receivable, after Allowance for Credit Loss	0	326,000
Nonperforming Financing Receivable | Construction Land Development [Member]
Financing Receivable, after Allowance for Credit Loss	0	0
Nonperforming Financing Receivable | Business [Member]
Financing Receivable, after Allowance for Credit Loss	0	0
Nonperforming Financing Receivable | Consumer
Financing Receivable, after Allowance for Credit Loss	43,000	44,000
Nonperforming Financing Receivable | Property total
Financing Receivable, after Allowance for Credit Loss	146,000	752,000
Nonperforming Financing Receivable | One-to-four family, residential, owner occupied
Financing Receivable, after Allowance for Credit Loss	103,000	382,000
Pass
Financing Receivable, after Allowance for Credit Loss	1,049,783,000	1,033,621,000
Special Mention
Financing Receivable, after Allowance for Credit Loss	15,838,000	2,519,000
Substandard
Financing Receivable, after Allowance for Credit Loss	680,000	1,289,000
Consumer [Member]
Financing Receivable, after Allowance for Credit Loss	17,891,000	12,970,000
Consumer [Member] | Pass
Financing Receivable, after Allowance for Credit Loss	17,848,000	12,926,000
Consumer [Member] | Special Mention
Financing Receivable, after Allowance for Credit Loss	0	0
Consumer [Member] | Substandard
Financing Receivable, after Allowance for Credit Loss	43,000	44,000
Business [Member]
Financing Receivable, after Allowance for Credit Loss	36,358,000	30,486,000
Business [Member] | Pass
Financing Receivable, after Allowance for Credit Loss	36,358,000	30,486,000
Business [Member] | Special Mention
Financing Receivable, after Allowance for Credit Loss	0	0
Business [Member] | Substandard
Financing Receivable, after Allowance for Credit Loss	0	0
Commercial Real Estate 1 [Member]
Financing Receivable, after Allowance for Credit Loss	384,202,000	373,798,000
Commercial Real Estate 1 [Member] | Pass
Financing Receivable, after Allowance for Credit Loss	383,669,000	372,690,000
Commercial Real Estate 1 [Member] | Special Mention
Financing Receivable, after Allowance for Credit Loss	533,000	782,000
Commercial Real Estate 1 [Member] | Substandard
Financing Receivable, after Allowance for Credit Loss	0	326,000
Multifamily
Financing Receivable, after Allowance for Credit Loss	161,460,000	169,355,000
Multifamily | Pass
Financing Receivable, after Allowance for Credit Loss	159,340,000	169,355,000
Multifamily | Special Mention
Financing Receivable, after Allowance for Credit Loss	2,120,000	0
Multifamily | Substandard
Financing Receivable, after Allowance for Credit Loss	0	0
One to four family residential
Financing Receivable, after Allowance for Credit Loss	361,256,000	341,966,000
One to four family residential | Pass
Financing Receivable, after Allowance for Credit Loss	360,005,000	339,310,000
One to four family residential | Special Mention
Financing Receivable, after Allowance for Credit Loss	614,000	1,737,000
One to four family residential | Substandard
Financing Receivable, after Allowance for Credit Loss	637,000	919,000
Construction Land Development [Member]
Financing Receivable, after Allowance for Credit Loss	105,134,000	108,854,000
Construction Land Development [Member] | Pass
Financing Receivable, after Allowance for Credit Loss	92,563,000	108,854,000
Construction Land Development [Member] | Special Mention
Financing Receivable, after Allowance for Credit Loss	12,571,000	0
Construction Land Development [Member] | Substandard
Financing Receivable, after Allowance for Credit Loss	$ 0	$ 0