Loans Receivable And Allowance For Credit Losses (Recorded Investment in Loans, Nonaccrual) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	$ 8,852	$ 7,541
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	5,313	4,436
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	1,553	1,023
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	775	1,551
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	670	0
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	172	173
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	347	337
Consumer Segment [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	$ 22	$ 21