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, 2013	Dec. 31, 2012
Debt securities, Available-for-sale, Amortized cost, Within one year	$ 156,780
Debt securities, Available-for-sale, Amortized cost, After one year through three years	190,728
Debt securities, Available-for-sale, Amortized cost, After three years through five years	123,055
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	40,262
Debt securities, Available-for-sale, Amortized cost, After ten years	314,553
Debt securities, Available-for-sale, Amortized cost, Total	1,236,110
Debt securities, Available-for-sale, Estimated fair value, Within one year	158,397
Debt securities, Available-for-sale, Estimated fair value, After one year through three years	193,606
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	121,942
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	37,896
Debt securities, Available-for-sale, Estimated fair value, After ten years	306,250
Debt securities, Available-for-sale, Estimated fair value, Total	1,231,571
Debt securities, Held-to-maturity, Amortized cost, Within one year
Debt securities, Held-to-maturity, Amortized cost, After one year through three years	15,057
Debt securities, Held-to-maturity, Amortized cost, After three years through five years	41,609
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years	384,547
Debt securities, Held-to-maturity, Amortized cost, After ten years	1,282,269
Held-to-maturity Securities, Amortized cost	1,723,482	708,008	[1]
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	14,669
Debt securities, Held-to-maturity, Estimated fair value, After three years through five years	39,306
Debt securities, Held-to-maturity, Estimated fair value, After five years through ten years	385,347
Debt securities, Held-to-maturity, Estimated fair value, After ten years	1,293,212
Held-to-maturity securities, Estimated fair value	1,732,534	715,274	[1]
Mortgage-backed securities [Member]
Debt securities, Available-for-sale, Amortized cost, After one year through three years	9,154
Debt securities, Available-for-sale, Amortized cost, After three years through five years	967
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	66,438
Debt securities, Available-for-sale, Amortized cost, After ten years	334,173
Debt securities, Available-for-sale, Estimated fair value, After one year through three years	9,355
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	991
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	66,131
Debt securities, Available-for-sale, Estimated fair value, After ten years	337,003
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
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 one year through three years
Debt securities, Held-to-maturity, Estimated fair value, After three years through five 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

[1] Held-to-maturity securities are carried at historical cost or at fair value at the time of transfer from the available-for-sale to held-to-maturity category, adjusted for amortization of premiums and accretion of discounts and credit-related other-than-temporary impairment.