Loans Receivable and Allowance for Credit Losses (Modifications, Subsequent Default) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			$ 1,353
Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			167
Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	$ 193		193
Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		$ 188	993	$ 205
One- to Four-Family Segment [Member] | Originated [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			423
One- to Four-Family Segment [Member] | Originated [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			82
One- to Four-Family Segment [Member] | Originated [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	193		193
One- to Four-Family Segment [Member] | Originated [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		188	148	205
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			426
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	0		0
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		0	426	0
One- to Four-Family Segment [Member] | Bulk Purchased [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	0		0
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		0	0	0
Commercial Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			192
Commercial Segment [Member] | Commercial Real Estate [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
Commercial Segment [Member] | Commercial Real Estate [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	0		0
Commercial Segment [Member] | Commercial Real Estate [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		0	192	0
Commercial Segment [Member] | Commercial and Industrial [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			227
Commercial Segment [Member] | Commercial and Industrial [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
Commercial Segment [Member] | Commercial and Industrial [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	0		0
Commercial Segment [Member] | Commercial and Industrial [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		0	227	0
Consumer Segment [Member] | Home Equity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			85
Consumer Segment [Member] | Home Equity [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			85
Consumer Segment [Member] | Home Equity [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	0		0
Consumer Segment [Member] | Home Equity [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		0	0	0
Consumer Segment [Member] | Other [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
Consumer Segment [Member] | Other [Member] | Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default			0
Consumer Segment [Member] | Other [Member] | Extended Maturity [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default	$ 0		0
Consumer Segment [Member] | Other [Member] | Extended Maturity and Payment Deferral [Member]
Financing Receivable, Modified, Subsequent Default [Line Items]
Amortized Cost, Modified, Subsequent Default		$ 0	$ 0	$ 0