v3.26.1
Loans Receivable And Allowance For Credit Losses (Loans, Past Due Aging Analysis) (Details) - USD ($)
$ in Thousands
Jun. 30, 2026
Sep. 30, 2025
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost $ 8,192,865 $ 8,136,000
Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 24,804 20,087
Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 13,959 12,363
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 10,845 7,724
Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 8,168,061 8,115,913
One- to Four-Family Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 5,610,679 5,914,446
One- to Four-Family Segment [Member] | Originated [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,640,236 3,776,443
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 11,012 10,071
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 7,042 7,320
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,970 2,751
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,629,224 3,766,372
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 1,864,904 2,023,397
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 5,461 4,508
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,012 3,098
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,449 1,410
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 1,859,443 2,018,889
One- to Four-Family Segment [Member] | Bulk Purchased [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 105,539 114,606
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 500 291
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 215 156
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 285 135
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 105,039 114,315
Commercial Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,464,207 2,107,939
Commercial Segment [Member] | Commercial Real Estate [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,190,959 1,898,183
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 4,879 4,359
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,058 1,236
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,821 3,123
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,186,080 1,893,824
Commercial Segment [Member] | Commercial and Industrial [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 273,248 209,756
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,277 243
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,133 32
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 144 211
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 270,971 209,513
Consumer Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 117,979 113,615
Consumer Segment [Member] | Home Equity [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 110,843 105,179
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 581 490
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 443 444
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 138 46
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 110,262 104,689
Consumer Segment [Member] | Other [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 7,136 8,436
Consumer Segment [Member] | Other [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 94 125
Consumer Segment [Member] | Other [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 56 77
Consumer Segment [Member] | Other [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 38 48
Consumer Segment [Member] | Other [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost $ 7,042 $ 8,311