Securities (Schedule Of Estimated Fair Value And Gross Unrealized Losses Of Securities In Continuous Unrealized Loss Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Marketable Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value	$ 297,848	$ 6,179
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses	1,311	109
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value	13,008	62,751
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses	781	1,514
MBS [Member]
Marketable Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value	181,310	6,179
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses	1,047	109
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value	9,668	34,555
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses	121	710
GSE Debentures [Member]
Marketable Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value	116,538	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses	264	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value	0	24,818
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses	0	182
Corporate Bonds [Member]
Marketable Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Estimated Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Estimated Fair Value	3,340	3,378
Available-for-sale Securities, Continuous Unrealized Loss Position, Equal to or Greater Than 12 Months, Unrealized Losses	$ 660	$ 622