Loans Receivable And Allowance For Loan Losses: Schedule of loans evaluated individually for impairment and collectively evaluated for impairment in the allowance for loan losses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	$ 105	$ 172
Allowance for Loan Losses, Collectively Evaluated for Impairment	9,777	9,518
Allowance for Loan Losses, Total	9,882	9,690	$ 9,533	$ 9,530
Recorded Investment in Loans, Individually Evaluated for Impairment	5,964	5,937
Recorded Investment in Loans, Collectively Evaluated for Impairment	919,902	893,213
Loans receivable	925,866	899,150
Mortgage loans, one-to-four family
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	1,065	1,167
Allowance for Loan Losses, Total	1,065	1,167	1,159	1,086
Recorded Investment in Loans, Individually Evaluated for Impairment	1,431	1,192
Recorded Investment in Loans, Collectively Evaluated for Impairment	127,942	131,469
Loans receivable	129,373	132,661
Mortgage loans, multi-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	499	481
Allowance for Loan Losses, Total	499	481	449	433
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	78,326	76,036
Loans receivable	78,326	76,036
Mortgage loans, commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	4,410	4,154
Allowance for Loan Losses, Total	4,410	4,154	4,239	4,248
Recorded Investment in Loans, Individually Evaluated for Impairment	3,141	3,190
Recorded Investment in Loans, Collectively Evaluated for Impairment	435,883	415,927
Loans receivable	439,024	419,117
Mortgage loans, construction - custom and owner/builder
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	754	755
Allowance for Loan Losses, Total	754	755	643	671
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	75,026	75,411
Loans receivable	75,026	75,411
Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	248	212
Allowance for Loan Losses, Total	248	212	206	178
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	12,473	10,779
Loans receivable	12,473	10,779
Mortgage loans, construction – commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	403	338
Allowance for Loan Losses, Total	403	338	386	563
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	27,151	24,051
Loans receivable	27,151	24,051
Mortgage loans, construction - Multi-family
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	333	375
Allowance for Loan Losses, Total	333	375	209	135
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	17,024	19,256
Loans receivable	17,024	19,256
Mortgage loans, construction - Land development
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	48	67
Allowance for Loan Losses, Total	48	67	143	49
Recorded Investment in Loans, Individually Evaluated for Impairment	0	0
Recorded Investment in Loans, Collectively Evaluated for Impairment	1,064	1,803
Loans receivable	1,064	1,803
Mortgage loans, land
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	28	27
Allowance for Loan Losses, Collectively Evaluated for Impairment	626	670
Allowance for Loan Losses, Total	654	697	757	844
Recorded Investment in Loans, Individually Evaluated for Impairment	198	204
Recorded Investment in Loans, Collectively Evaluated for Impairment	29,221	30,566
Loans receivable	29,419	30,770
Consumer loans, home equity and second mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	0	0
Allowance for Loan Losses, Collectively Evaluated for Impairment	609	623
Allowance for Loan Losses, Total	609	623	666	649
Recorded Investment in Loans, Individually Evaluated for Impairment	581	603
Recorded Investment in Loans, Collectively Evaluated for Impairment	38,522	39,587
Loans receivable	39,103	40,190
Consumer loans, other
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	6	17
Allowance for Loan Losses, Collectively Evaluated for Impairment	81	82
Allowance for Loan Losses, Total	87	99	101	117
Recorded Investment in Loans, Individually Evaluated for Impairment	12	23
Recorded Investment in Loans, Collectively Evaluated for Impairment	4,081	4,289
Loans receivable	4,093	4,312
Commercial business loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for Loan Losses, Individually Evaluated for Impairment	71	128
Allowance for Loan Losses, Collectively Evaluated for Impairment	701	594
Allowance for Loan Losses, Total	772	722	$ 575	$ 557
Recorded Investment in Loans, Individually Evaluated for Impairment	601	725
Recorded Investment in Loans, Collectively Evaluated for Impairment	73,189	64,039
Loans receivable	$ 73,790	$ 64,764