Loans Receivable and Allowance for Loan Losses: Schedule of Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	$ 9,553	$ 9,826	$ 9,924
Provision for (Recapture of) Loan Losses	0	(1,250)	0
Charge-offs	(56)	(133)	(368)
Recoveries	33	1,110	270
Allowance for loan losses, Ending Allowance	9,530	9,553	9,826
Mortgage loans, one-to-four family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	1,082	1,239	1,480
Provision for (Recapture of) Loan Losses	4	(178)	(225)
Charge-offs	0	0	(72)
Recoveries	0	21	56
Allowance for loan losses, Ending Allowance	1,086	1,082	1,239
Mortgage loans, multi-family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	447	473	392
Provision for (Recapture of) Loan Losses	(14)	(26)	81
Charge-offs	0	0	0
Recoveries	0	0	0
Allowance for loan losses, Ending Allowance	433	447	473
Mortgage loans, commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	4,184	4,384	4,065
Provision for (Recapture of) Loan Losses	92	(1,248)	528
Charge-offs	(28)	(13)	(209)
Recoveries	0	1,061	0
Allowance for loan losses, Ending Allowance	4,248	4,184	4,384
Mortgage loans, construction - custom and owner/builder
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	699	619	451
Provision for (Recapture of) Loan Losses	(28)	80	168
Charge-offs	0	0	0
Recoveries	0	0	0
Allowance for loan losses, Ending Allowance	671	699	619
Mortgage loans, construction - speculative one-to-four family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	128	130	123
Provision for (Recapture of) Loan Losses	37	(8)	5
Charge-offs	0	0	0
Recoveries	13	6	2
Allowance for loan losses, Ending Allowance	178	128	130
Mortgage loans, construction - commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	303	268	426
Provision for (Recapture of) Loan Losses	260	35	(158)
Charge-offs	0	0	0
Recoveries	0	0	0
Allowance for loan losses, Ending Allowance	563	303	268
Mortgage loans, construction - multi-family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	173	316	283
Provision for (Recapture of) Loan Losses	(38)	(143)	(148)
Charge-offs	0	0	0
Recoveries	0	0	181
Allowance for loan losses, Ending Allowance	135	173	316
Mortgage loans - construction - land development
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	0
Provision for (Recapture of) Loan Losses	49
Charge-offs	0
Recoveries	0
Allowance for loan losses, Ending Allowance	49	0
Mortgage loans, land
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	918	820	1,021
Provision for (Recapture of) Loan Losses	(71)	189	(164)
Charge-offs	(22)	(110)	(61)
Recoveries	19	19	24
Allowance for loan losses, Ending Allowance	844	918	820
Consumer loans, home equity and second mortgage
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	983	939	1,073
Provision for (Recapture of) Loan Losses	(334)	44	(116)
Charge-offs	0	0	(18)
Recoveries	0	0	0
Allowance for loan losses, Ending Allowance	649	983	939
Consumer loans, other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	121	156	187
Provision for (Recapture of) Loan Losses	1	(28)	(25)
Charge-offs	(6)	(10)	(8)
Recoveries	1	3	2
Allowance for loan losses, Ending Allowance	117	121	156
Commercial business loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for loan losses, Beginning Allowance	515	482	423
Provision for (Recapture of) Loan Losses	42	33	54
Charge-offs	0	0	0
Recoveries	0	0	5
Allowance for loan losses, Ending Allowance	$ 557	$ 515	$ 482

A valuation allowance for financing receivables that are expected to be uncollectible.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of direct write-downs of financing receivables charged against the allowance.

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- Definition

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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