Loans And Allowance For Credit Losses (Schedule Of Recorded Investment In Loan Receivables That Are Past Due) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 15,737,556	$ 15,392,061
Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	12,548	12,502
Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,842	5,452
Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	17,261	13,934
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	34,651	31,888
Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	15,702,905	15,360,173
Real Estate Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	15,729,403	15,386,356
Real Estate Loans | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	10,830,505	11,408,854
Real Estate Loans | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	35,471	40,471
Real Estate Loans | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	7,272	10,015
Real Estate Loans | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,100,665	3,360,143
Real Estate Loans | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	755,490	566,873
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	12,548	12,502
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	6,494	7,554
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	752	814
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,791	3,556
Real Estate Loans | Financing Receivables, 30 to 59 Days Past Due | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	511	578
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,842	5,452
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	2,855	4,024
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	266	307
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,382	1,014
Real Estate Loans | Financing Receivables, 60 to 89 Days Past Due | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	339	107
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	17,261	13,934
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	10,470	8,881
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	560	693
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	5,296	4,078
Real Estate Loans | Financing Receivables, Equal to Greater than 90 Days Past Due | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	935	282
Real Estate Loans | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	34,651	31,888
Real Estate Loans | Financial Asset, Past Due | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	19,819	20,459
Real Estate Loans | Financial Asset, Past Due | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,578	1,814
Real Estate Loans | Financial Asset, Past Due | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Real Estate Loans | Financial Asset, Past Due | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	11,469	8,648
Real Estate Loans | Financial Asset, Past Due | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	1,785	967
Real Estate Loans | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	15,694,752	15,354,468
Real Estate Loans | Financial Asset, Not Past Due | Residential Core
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	10,810,686	11,388,395
Real Estate Loans | Financial Asset, Not Past Due | Residential Home Today
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	33,893	38,657
Real Estate Loans | Financial Asset, Not Past Due | Construction Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	7,272	10,015
Real Estate Loans | Financial Asset, Not Past Due | Home Equity Line of Credit
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	4,089,196	3,351,495
Real Estate Loans | Financial Asset, Not Past Due | Home Equity Loan
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	753,705	565,906
Other Loans
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	8,153	5,705
Other Loans | Financing Receivables, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Other Loans | Financing Receivables, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Other Loans | Financing Receivables, Equal to Greater than 90 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Other Loans | Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	0	0
Other Loans | Financial Asset, Not Past Due
Financing Receivable, Past Due [Line Items]
Financing Receivable, before Allowance for Credit Loss	$ 8,153	$ 5,705