Available-For-Sale And Held-To-Maturity Securities (Schedule Of Amortized Cost And Fair Values Of Debt Securities By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Debt securities, Available-for-sale, Amortized cost, Within one year	$ 140,404
Debt securities, Available-for-sale, Amortized cost, After one year through three years	316,768
Debt securities, Available-for-sale, Amortized cost, After three years through five years	77,537
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	5,626
Debt securities, Available-for-sale, Amortized cost, After ten years	119,355
Debt securities, Available-for-sale, Amortized cost, Total	1,446,097
Debt securities, Available-for-sale, Estimated fair value, Within one year	141,051
Debt securities, Available-for-sale, Estimated fair value, After one year through three years	323,487
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	76,602
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	6,249
Debt securities, Available-for-sale, Estimated fair value, After ten years	124,387
Debt securities, Available-for-sale, Estimated fair value, Total	1,476,681
Debt securities, Held-to-maturity, Amortized cost, Within one year
Debt securities, Held-to-maturity, Amortized cost, After one year through three years
Debt securities, Held-to-maturity, Amortized cost, After three years through five years	32,943
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years	226,638
Debt securities, Held-to-maturity, Amortized cost, After ten years	398,352
Debt securities, Held-to-maturity, Amortized cost, Total	657,933
Debt securities, Held-to-maturity, Estimated fair value, Within one year
Debt securities, Held-to-maturity, Estimated fair value, After one year through three years
Debt securities, Held-to-maturity, Estimated fair value, After three years through five years	32,818
Debt securities, Held-to-maturity, Estimated fair value, After five years through ten years	226,503
Debt securities, Held-to-maturity, Estimated fair value, After ten years	405,272
Debt securities, Held-to-maturity, Estimated fair value, Total	664,593
Mortgage-backed securities [Member]
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	6,650
Debt securities, Available-for-sale, Amortized cost, After ten years	779,368
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	7,007
Debt securities, Available-for-sale, Estimated fair value, After ten years	797,499
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years
Debt securities, Held-to-maturity, Amortized cost, After ten years
Debt securities, Held-to-maturity, Estimated fair value, After five years through ten years
Debt securities, Held-to-maturity, Estimated fair value, After ten years