Loans Receivable And Allowance for Credit Losses (Financial Effect of Modifications) (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
One- to Four-Family Segment [Member] \| Originated [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	9 months	8 months	8 months	8 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	24 months	20 months	40 months	18 months
One- to Four-Family Segment [Member] \| Correspondent Purchased [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	8 months	9 months	8 months	9 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	18 months	34 months	19 months	34 months
One- to Four-Family Segment [Member] \| Bulk Purchased [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	13 months		13 months
Commercial Segment [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	6 months	9 months	11 months	9 months
Commercial Segment [Member] \| Commercial and Industrial [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	60 months		60 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	60 months	3 months	60 months	3 months
Consumer Segment [Member] \| Home Equity [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	8 months		8 months	7 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification		14 months		14 months