Fair Value Measurements: Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Recorded Amount
Fair value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 314,452	$ 143,015
CDs held for investment	65,545	78,346
Investment securities	85,797	53,634
Investments in equity securities	977	958
FHLB stock	1,922	1,437
Other investments	3,000	3,000
Loans held for sale	4,509	6,071
Loans receivable, net	1,013,875	886,662
Accrued interest receivable	4,484	3,598
Certificates of deposit	158,524	165,655
Accrued interest payable	274	333
Fair Value
Fair value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	314,452	143,015
CDs held for investment	65,545	78,346
Investment securities	87,734	55,112
Investments in equity securities	977	958
FHLB stock	1,922	1,437
Other investments	3,000	3,000
Loans held for sale	4,664	6,260
Loans receivable, net	1,034,876	892,495
Accrued interest receivable	4,484	3,598
Certificates of deposit	160,921	166,852
Accrued interest payable	274	333
Fair Value \| Fair Value, Inputs, Level 1
Fair value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	314,452	143,015
CDs held for investment	65,545	78,346
Investment securities	0	3,949
Investments in equity securities	977	958
FHLB stock	1,922	1,437
Other investments	3,000	3,000
Loans held for sale	4,664	6,260
Loans receivable, net	0	0
Accrued interest receivable	4,484	3,598
Certificates of deposit	0	0
Accrued interest payable	274	333
Fair Value \| Fair Value, Inputs, Level 2
Fair value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
CDs held for investment	0	0
Investment securities	87,235	51,163
Investments in equity securities	0	0
FHLB stock	0	0
Other investments	0	0
Loans held for sale	0	0
Loans receivable, net	0	0
Accrued interest receivable	0	0
Certificates of deposit	0	0
Accrued interest payable	0	0
Fair Value \| Fair Value, Inputs, Level 3
Fair value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
CDs held for investment	0	0
Investment securities	499	0
Investments in equity securities	0	0
FHLB stock	0	0
Other investments	0	0
Loans held for sale	0	0
Loans receivable, net	1,034,876	892,495
Accrued interest receivable	0	0
Certificates of deposit	160,921	166,852
Accrued interest payable	$ 0	$ 0

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The fair value as of the balance sheet date of firm holdings in mortgages, mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings.

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-Publisher FASB
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-SubTopic 320
-Section 45
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- Definition

Fair value portion of investments in Federal Home Loan Bank (FHLBank) stock.

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-SubTopic 10
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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
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- Definition

Amount of investments classified as other.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
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