v3.25.4
Fair Value (Estimated Fair Value Of Financial Instruments) (Details) - USD ($)
$ in Thousands
Dec. 31, 2025
Sep. 30, 2025
Carrying Amount    
Assets:    
Investment securities, available for sale $ 454,493 $ 520,659
Mortgage loans held for sale 14,440 57,662
Federal Home Loan Bank stock 234,027 235,363
Cash collateral received from or held by counterparty 58,809 6,910
Derivative 0 272
Liabilities:    
Borrowed funds 4,939,835 4,870,219
Carrying Amount | Checking And Passbook Accounts    
Liabilities:    
Deposits 2,374,992 1,957,745
Carrying Amount | Certificates of Deposit    
Liabilities:    
Deposits 7,997,083 8,489,223
Carrying Amount | Borrowers' Advances for insurance and Taxes    
Liabilities:    
Other Liabilities 133,606 113,168
Carrying Amount | Principal, Interest, And Escrow Owed On Loans Serviced    
Liabilities:    
Other Liabilities 42,256 30,328
Carrying Amount | Forward Commitments For Sale Of Mortgage Loans    
Liabilities:    
Derivative Liability 63 351
Carrying Amount | Cash and Due From Banks    
Assets:    
Cash and Cash Equivalents 26,722 24,176
Carrying Amount | Interest Earning Cash Equivalents    
Assets:    
Cash and Cash Equivalents 429,987 405,263
Carrying Amount | Total real estate loans    
Assets:    
Loans, net 15,733,173 15,655,159
Carrying Amount | Other Loans    
Assets:    
Loans, net 8,515 8,153
Carrying Amount | Accrued Interest Receivable    
Assets:    
Accrued interest receivable 60,295 62,553
Investment securities, available for sale 454,493 520,659
Mortgage loans held for sale 14,488 58,325
Federal Home Loan Bank stock 234,027 235,363
Cash collateral received from or held by counterparty 58,809 6,910
Derivative 0 272
Liabilities:    
Borrowed funds 4,968,266 4,892,273
Checking And Passbook Accounts    
Liabilities:    
Deposits 2,374,992 1,957,745
Certificates of Deposit    
Liabilities:    
Deposits 8,014,295 8,511,443
Borrowers' Advances for insurance and Taxes    
Liabilities:    
Other Liabilities 133,606 113,168
Principal, Interest, And Escrow Owed On Loans Serviced    
Liabilities:    
Other Liabilities 42,256 30,328
Forward Commitments For Sale Of Mortgage Loans    
Liabilities:    
Derivative Liability 63 351
Cash and Due From Banks    
Assets:    
Cash and Cash Equivalents 26,722 24,176
Interest Earning Cash Equivalents    
Assets:    
Cash and Cash Equivalents 429,987 405,263
Total real estate loans    
Assets:    
Loans, net 14,678,418 14,564,394
Other Loans    
Assets:    
Loans, net 8,515 8,153
Accrued Interest Receivable    
Assets:    
Accrued interest receivable 60,295 62,553
Fair Value, Inputs, Level 1    
Assets:    
Investment securities, available for sale 0 0
Mortgage loans held for sale 0 0
Cash collateral received from or held by counterparty 58,809 6,910
Derivative 0 0
Liabilities:    
Borrowed funds 0 0
Fair Value, Inputs, Level 1 | Checking And Passbook Accounts    
Liabilities:    
Deposits 0 0
Fair Value, Inputs, Level 1 | Certificates of Deposit    
Liabilities:    
Deposits 0 0
Fair Value, Inputs, Level 1 | Borrowers' Advances for insurance and Taxes    
Liabilities:    
Other Liabilities 0 0
Fair Value, Inputs, Level 1 | Principal, Interest, And Escrow Owed On Loans Serviced    
Liabilities:    
Other Liabilities 0 0
Fair Value, Inputs, Level 1 | Forward Commitments For Sale Of Mortgage Loans    
Liabilities:    
Derivative Liability 0 0
Fair Value, Inputs, Level 1 | Cash and Due From Banks    
Assets:    
Cash and Cash Equivalents 26,722 24,176
Fair Value, Inputs, Level 1 | Interest Earning Cash Equivalents    
Assets:    
Cash and Cash Equivalents 429,987 405,263
Fair Value, Inputs, Level 1 | Total real estate loans    
Assets:    
Loans, net 0 0
Fair Value, Inputs, Level 1 | Other Loans    
Assets:    
Loans, net 0 0
Fair Value, Inputs, Level 1 | Accrued Interest Receivable    
Assets:    
Accrued interest receivable 0 0
Fair Value, Inputs, Level 2    
Assets:    
Investment securities, available for sale 454,493 520,659
Mortgage loans held for sale 14,488 58,325
Federal Home Loan Bank stock 0 0
Cash collateral received from or held by counterparty 0 0
Derivative 0 0
Liabilities:    
Borrowed funds 4,968,266 4,892,273
Fair Value, Inputs, Level 2 | Checking And Passbook Accounts    
Liabilities:    
Deposits 2,374,992 1,957,745
Fair Value, Inputs, Level 2 | Certificates of Deposit    
Liabilities:    
Deposits 8,014,295 8,511,443
Fair Value, Inputs, Level 2 | Borrowers' Advances for insurance and Taxes    
Liabilities:    
Other Liabilities 133,606 113,168
Fair Value, Inputs, Level 2 | Principal, Interest, And Escrow Owed On Loans Serviced    
Liabilities:    
Other Liabilities 42,256 30,328
Fair Value, Inputs, Level 2 | Forward Commitments For Sale Of Mortgage Loans    
Liabilities:    
Derivative Liability 63 351
Fair Value, Inputs, Level 2 | Cash and Due From Banks    
Assets:    
Cash and Cash Equivalents 0 0
Fair Value, Inputs, Level 2 | Interest Earning Cash Equivalents    
Assets:    
Cash and Cash Equivalents 0 0
Fair Value, Inputs, Level 2 | Total real estate loans    
Assets:    
Loans, net 0 0
Fair Value, Inputs, Level 2 | Other Loans    
Assets:    
Loans, net 0 0
Fair Value, Inputs, Level 2 | Accrued Interest Receivable    
Assets:    
Accrued interest receivable 60,295 62,553
Fair Value, Inputs, Level 3    
Assets:    
Investment securities, available for sale 0 0
Mortgage loans held for sale 0 0
Federal Home Loan Bank stock 0 0
Cash collateral received from or held by counterparty 0 0
Derivative 0 272
Liabilities:    
Borrowed funds 0 0
Fair Value, Inputs, Level 3 | Checking And Passbook Accounts    
Liabilities:    
Deposits 0 0
Fair Value, Inputs, Level 3 | Certificates of Deposit    
Liabilities:    
Deposits 0 0
Fair Value, Inputs, Level 3 | Borrowers' Advances for insurance and Taxes    
Liabilities:    
Other Liabilities 0 0
Fair Value, Inputs, Level 3 | Principal, Interest, And Escrow Owed On Loans Serviced    
Liabilities:    
Other Liabilities 0 0
Fair Value, Inputs, Level 3 | Forward Commitments For Sale Of Mortgage Loans    
Liabilities:    
Derivative Liability 0 0
Fair Value, Inputs, Level 3 | Cash and Due From Banks    
Assets:    
Cash and Cash Equivalents 0 0
Fair Value, Inputs, Level 3 | Interest Earning Cash Equivalents    
Assets:    
Cash and Cash Equivalents 0 0
Fair Value, Inputs, Level 3 | Total real estate loans    
Assets:    
Loans, net 14,678,418 14,564,394
Fair Value, Inputs, Level 3 | Other Loans    
Assets:    
Loans, net 8,515 8,153
Fair Value, Inputs, Level 3 | Accrued Interest Receivable    
Assets:    
Accrued interest receivable $ 0 $ 0