Fair Value Of Financial Instruments (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Assets:
AFS securities	$ 1,236,037	$ 1,204,863
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Loans receivable	4,900		$ 2,800
Carrying Amount [Member]
Assets:
Cash and cash equivalents	118,374	220,370
AFS securities	1,236,037	1,204,863
Loans receivable	7,476,805	7,416,747
FHLB stock	101,575	98,456
Liabilities:
Deposits	5,774,619	5,581,867
Borrowings	2,115,869	2,239,989
Interest rate swaps	55,555	33,090
Estimated Fair Value [Member]
Assets:
Cash and cash equivalents	118,374	220,370
AFS securities	1,236,037	1,204,863
Loans receivable	7,934,879	7,654,586
FHLB stock	101,575	98,456
Liabilities:
Deposits	5,852,187	5,614,895
Borrowings	2,165,705	2,253,353
Interest rate swaps	55,555	33,090
Estimated Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Cash and cash equivalents	118,374	220,370
AFS securities	0	0
Loans receivable	0	0
FHLB stock	101,575	98,456
Liabilities:
Deposits	2,732,263	2,594,242
Borrowings	30,000	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	1,236,037	1,204,863
Loans receivable	0	0
FHLB stock	0	0
Liabilities:
Deposits	3,119,924	3,020,653
Borrowings	2,135,705	2,153,352
Interest rate swaps	55,555	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	7,934,879	7,654,586
FHLB stock	0	0
Liabilities:
Deposits	0	0
Borrowings	0	0
Interest rate swaps	$ 0	$ 0