Loans Receivable And Allowance For Credit Losses (Troubled Debt Restructurings On Financing Receivables That Subsequently Defaulted) (Details) $ in Thousands	12 Months Ended
Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract	Sep. 30, 2018 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	3	1	30
Recorded Investment \| $	$ 181	$ 45	$ 2,713
One- to Four-Family Segment [Member] \| Originated [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	1	1	22
Recorded Investment \| $	$ 38	$ 45	$ 1,416
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	0	0	1
Recorded Investment \| $	$ 0	$ 0	$ 124
One- to Four-Family Segment [Member] \| Bulk Purchased [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	1	0	3
Recorded Investment \| $	$ 134	$ 0	$ 1,040
Commercial Segment [Member] \| Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	0	0	0
Recorded Investment \| $	$ 0	$ 0	$ 0
Commercial Segment [Member] \| Commercial and Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	0	0	0
Recorded Investment \| $	$ 0	$ 0	$ 0
Consumer Segment [Member] \| Home Equity [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	1	0	4
Recorded Investment \| $	$ 9	$ 0	$ 133
Consumer Segment [Member] \| Other [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts \| contract	0	0	0
Recorded Investment \| $	$ 0	$ 0	$ 0

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Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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- Definition

Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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