Loans And Allowance For Loan Losses (Loan Forbearance By Portfolio) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 13,421,002	$ 13,234,658
Accrued interest receivable	37,680	40,822
Active Forbearance Plans
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	230,337
Accrued interest receivable	1,990
Active Forbearance Plans | Troubled Debt Restructuring
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	16,601
Real Estate Loans
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	13,418,282	13,231,492
Real Estate Loans | Residential Non Home Today [Member]
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	11,003,681	10,918,701
Real Estate Loans | Residential Home Today
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	77,375	84,614
Real Estate Loans | Home Equity Loans And Lines Of Credit
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	2,311,728	$ 2,201,982
Real Estate Loans | Active Forbearance Plans
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 230,337
Residential real estate loans held, percent	1.72%
Real Estate Loans | Active Forbearance Plans | Residential Non Home Today [Member]
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 195,744
Residential real estate loans held, percent	1.78%
Real Estate Loans | Active Forbearance Plans | Residential Home Today
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 6,827
Residential real estate loans held, percent	8.82%
Real Estate Loans | Active Forbearance Plans | Home Equity Loans And Lines Of Credit
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 27,766
Residential real estate loans held, percent	1.20%
Real Estate Loans | Short-Term Forbearance | Residential Non Home Today [Member]
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 1,575
Real Estate Loans | Short-Term Forbearance | Home Equity Loans And Lines Of Credit
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	179
Real Estate Loans | Modification | Residential Non Home Today [Member]
Financing Receivable, Loan Forbearance [Line Items]
Real estate loans	$ 2,619