Loans Receivable and Allowance for Credit Losses (Financial Effect of Modifications) (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	8 months	8 months	8 months	4 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	26 months	20 months	23 months	31 months
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	8 months		8 months	4 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	27 months		44 months	17 months
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period	8 months		8 months	24 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification				24 months
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period		6 months		6 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification	6 months	9 months	5 months	6 months
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Modified [Line Items]
Financing Receivable, Modified, Payment Deferral, Period			7 months
Financing Receivable, Modified, Weighted Average Term Increase from Modification			14 months