Securities (Schedule Of Contractual Maturities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	$ 1,191,455	$ 718,564
Available-for-sale Securities, Estimated Fair Value	1,204,863	714,614
Debt Securities [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, One year or less, Amortized Cost	57,744
Available-for-sale Securities, One year through five years, Amortized Cost	210,455
Available-for-sale Securities, Amortized Cost	268,199
Available-for-sale Securities, One year or less, Estimated Fair Value	57,633
Available-for-sale Securities, One year through five years, Estimated Fair Value	210,743
Available-for-sale Securities, Estimated Fair Value	268,376
MBS [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	923,256	445,883
Available-for-sale Securities, Estimated Fair Value	$ 936,487	$ 445,090

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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