Loans Receivable And Allowance For Credit Losses (LTV And Credit Score Information For Originated, Correspondent Purchased, And Bulk Purchased One-To Four-Family Loans And Originated Consumer Home Equity Loans) (Details) - credit_score	Jun. 30, 2020	Sep. 30, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average credit score	768	766
Weighted average LTV	62.00%	62.00%
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average credit score	770	768
Weighted average LTV	62.00%	62.00%
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average credit score	765	765
Weighted average LTV	64.00%	65.00%
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average credit score	768	762
Weighted average LTV	60.00%	61.00%
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Weighted average credit score	755	754
Weighted average LTV	19.00%	19.00%