v3.26.1
Loans Receivable and Allowance for Credit Losses (Modifications, Subsequent Default) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2026
Mar. 31, 2025
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default $ 787 $ 1,122 $ 1,234 $ 1,363
Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 148 172 148 172
Extended Maturity [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 169 193 462 193
Extended Maturity and Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 470 757 624 998
One- to Four-Family Segment [Member] | Originated [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 639 428 1,086 428
One- to Four-Family Segment [Member] | Originated [Member] | Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 84 0 84
One- to Four-Family Segment [Member] | Originated [Member] | Extended Maturity [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 169 193 462 193
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 470 151 624 151
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 187 0 428
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 0 0 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 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 0 187 0 428
One- to Four-Family Segment [Member] | Bulk Purchased [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 0 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 0 0 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 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 0
Commercial Segment [Member] | Commercial Real Estate [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 148 192 148 192
Commercial Segment [Member] | Commercial Real Estate [Member] | Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 148 0 148 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 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 0 192
Commercial Segment [Member] | Commercial and Industrial [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 227 0 227
Commercial Segment [Member] | Commercial and Industrial [Member] | Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 0 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 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 0 227
Consumer Segment [Member] | Home Equity [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 88 0 88
Consumer Segment [Member] | Home Equity [Member] | Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 88 0 88
Consumer Segment [Member] | Home Equity [Member] | Extended Maturity [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 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 0
Consumer Segment [Member] | Other [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 0 0
Consumer Segment [Member] | Other [Member] | Payment Deferral [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 0 0
Consumer Segment [Member] | Other [Member] | Extended Maturity [Member]        
Financing Receivable, Modified, Subsequent Default [Line Items]        
Amortized Cost, Modified, Subsequent Default 0 0 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 $ 0