v3.25.1
Loans Receivable And Allowance For Credit Losses (Loans, Past Due Aging Analysis) (Details) - USD ($)
$ in Thousands
Mar. 31, 2025
Sep. 30, 2024
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost $ 7,899,875 $ 7,930,373
Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 24,049 25,630
Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 14,459 16,049
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 9,590 9,581
Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 7,875,826 7,904,743
One- to Four-Family Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 6,128,880 6,316,779
One- to Four-Family Segment [Member] | Originated [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,866,343 3,950,046
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 10,858 11,135
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 8,052 8,864
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 2,806 2,271
One- to Four-Family Segment [Member] | Originated [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 3,855,485 3,938,911
One- to Four-Family Segment [Member] | Correspondent Purchased [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,142,220 2,239,143
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 4,959 7,179
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 2,965 3,089
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 1,994 4,090
One- to Four-Family Segment [Member] | Correspondent Purchased [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 2,137,261 2,231,964
One- to Four-Family Segment [Member] | Bulk Purchased [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 120,317 127,590
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 804 1,608
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 181 69
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 623 1,539
One- to Four-Family Segment [Member] | Bulk Purchased [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 119,513 125,982
Commercial Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 1,662,208 1,503,732
Commercial Segment [Member] | Commercial Real Estate [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 1,526,318 1,374,054
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 5,787 4,156
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 2,471 2,993
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 3,316 1,163
Commercial Segment [Member] | Commercial Real Estate [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 1,520,531 1,369,898
Commercial Segment [Member] | Commercial and Industrial [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 135,890 129,678
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 725 473
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 348 391
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 377 82
Commercial Segment [Member] | Commercial and Industrial [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 135,165 129,205
Consumer Segment [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 108,787 109,862
Consumer Segment [Member] | Home Equity [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 99,353 100,247
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 762 809
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 361 471
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 401 338
Consumer Segment [Member] | Home Equity [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 98,591 99,438
Consumer Segment [Member] | Other [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 9,434 9,615
Consumer Segment [Member] | Other [Member] | Financial Asset, Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 154 270
Consumer Segment [Member] | Other [Member] | Financial Asset, 30 to 89 Days Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost 81 172
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 73 98
Consumer Segment [Member] | Other [Member] | Financial Asset, Not Past Due [Member]    
Financing Receivable, Past Due [Line Items]    
Total Amortized Cost $ 9,280 $ 9,345