Fair Value Of Financial Instruments (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019
Assets:
AFS securities	$ 1,220,054	$ 1,204,863
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Loans receivable	6,000		$ 4,600
Carrying Amount [Member]
Assets:
Cash and cash equivalents	396,219	220,370
AFS securities	1,220,054	1,204,863
Loans receivable	7,388,090	7,416,747
FHLB stock	102,782	98,456
Liabilities:
Deposits	6,069,684	5,581,867
Borrowings	1,989,089	2,239,989
Interest rate swaps	57,067	33,090
Estimated Fair Value [Member]
Assets:
Cash and cash equivalents	396,219	220,370
AFS securities	1,220,054	1,204,863
Loans receivable	7,845,259	7,654,586
FHLB stock	102,782	98,456
Liabilities:
Deposits	6,155,296	5,614,895
Borrowings	2,042,101	2,253,353
Interest rate swaps	57,067	33,090
Estimated Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash and cash equivalents	396,219	220,370
AFS securities	0	0
Loans receivable	0	0
FHLB stock	102,782	98,456
Liabilities:
Deposits	3,036,524	2,594,242
Borrowings	0	100,001
Interest rate swaps	0	0
Estimated Fair Value [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Cash and cash equivalents	0	0
AFS securities	1,220,054	1,204,863
Loans receivable	0	0
FHLB stock	0	0
Liabilities:
Deposits	3,118,772	3,020,653
Borrowings	2,042,101	2,153,352
Interest rate swaps	57,067	33,090
Estimated Fair Value [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets:
Cash and cash equivalents	0	0
AFS securities	0	0
Loans receivable	7,845,259	7,654,586
FHLB stock	0	0
Liabilities:
Deposits	0	0
Borrowings	0	0
Interest rate swaps	$ 0	$ 0