Loans Receivable And Allowance For Credit Losses (Recorded Investment in Loans, Nonaccrual) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	$ 12,541	$ 7,541
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	5,037	4,436
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	2,433	1,023
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	2,938	1,551
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	1,663	0
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	157	173
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	305	337
Consumer Segment [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Financing receivable, nonaccrual loans	$ 8	$ 21