Securities (Schedule Of Contractual Maturities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Securities [Abstract]
Available-for-sale Securities, One year or less, Amortized Cost	$ 191
Available-for-sale Securities, One year through five years, Amortized Cost	639,588
Available-for-sale Securities, Five years through ten years, Amortized Cost	267,606
Available-for-sale Securities, Ten years and thereafter, Amortized Cost	319,206
Available-for-sale Securities, Amortized Cost	1,226,591	1,367,925
Available-for-sale Securities, One year or less, Estimated Fair Value	195
Available-for-sale Securities, One year through five years, Estimated Fair Value	643,338
Available-for-sale Securities, Five years through ten years, Estimated Fair Value	278,305
Available-for-sale Securities, Ten years and thereafter, Estimated Fair Value	337,554
Available-for-sale Securities, Total	1,259,392	1,406,844
Held-to-maturity Securities, One year or less, Amortized Cost	5,136
Held-to-maturity Securities, One year through five years, Amortized Cost	54,557
Held-to-maturity Securities, Five years through ten years, Amortized Cost	390,391
Held-to-maturity Securities, Ten years and thereafter, Amortized Cost	1,452,144
Held-to-maturity Securities, Amortized Cost	1,902,228	1,887,947
Held-to-maturity Securities, One year or less, Estimated Fair Value	5,181
Held-to-maturity Securities, One year through five years, Estimated Fair Value	55,836
Held-to-maturity Securities, Five years through ten years, Estimated Fair Value	404,936
Held-to-maturity Securities, Ten years and thereafter, Estimated Fair Value	1,508,162
Held-to-maturity Securities, Total	$ 1,974,115	$ 1,969,899