Securities (Schedule Of Contractual Maturities) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	$ 1,186,225	$ 1,191,455
Available-for-sale Securities, Estimated Fair Value	1,220,054	1,204,863
Debt Securities [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, One year or less, Amortized Cost	5,467
Available-for-sale Securities, One year through five years, Amortized Cost	231,410
Available-for-sale Securities, Amortized Cost	236,877
Available-for-sale Securities, One year or less, Estimated Fair Value	5,497
Available-for-sale Securities, One year through five years, Estimated Fair Value	231,970
Available-for-sale Securities, Estimated Fair Value	237,467
MBS [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	949,348	923,256
Available-for-sale Securities, Estimated Fair Value	$ 982,587	$ 936,487

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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