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	Dec. 31, 2014	Dec. 31, 2013
Schedule of Debt Securities at Amortized Cost and Fair Value Basis [Line Items]
Debt securities, Available-for-sale, Amortized cost, Total	$ 1,520,517
Debt securities, Available-for-sale, Estimated fair value, Within one year	132,432
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	379,476
Debt securities, Available-for-sale, Estimated fair value, After ten years	831,884
Debt securities, Available-for-sale, Estimated fair value, Total	1,513,478
Debt securities, Held-to-maturity, Amortized cost, Within one year	15,025
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years	59,462
Debt securities, Held-to-maturity, Amortized cost, After ten years	1,062,867
Held-to-maturity Securities, Amortized cost	1,177,565	1,312,115
Held-to-maturity securities, Estimated fair value	1,211,976	1,305,959
Excluding Mortgage Backed Securities [Member]
Schedule of Debt Securities at Amortized Cost and Fair Value Basis [Line Items]
Debt securities, Available-for-sale, Amortized cost, Within one year	132,004
Debt securities, Available-for-sale, Amortized cost, After one year through three years	46,936
Debt securities, Available-for-sale, Amortized cost, After three years through five years	121,655
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	299,752
Debt securities, Available-for-sale, Amortized cost, After ten years	602,902
Debt securities, Available-for-sale, Estimated fair value, Within one year	132,432
Debt securities, Available-for-sale, Estimated fair value, After one year through three years	47,253
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	122,311
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	298,294
Debt securities, Available-for-sale, Estimated fair value, After ten years	593,201
Debt securities, Held-to-maturity, Amortized cost, Within one year	15,025
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	40,211
Debt securities, Held-to-maturity, Amortized cost, After five years through ten years
Debt securities, Held-to-maturity, Amortized cost, After ten years	177,335
Debt securities, Held-to-maturity, Estimated fair value, Within one year	15,027
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	38,991
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	177,840
Mortgage-backed securities [Member]
Schedule of Debt Securities at Amortized Cost and Fair Value Basis [Line Items]
Debt securities, Available-for-sale, Amortized cost, After one year through three years
Debt securities, Available-for-sale, Amortized cost, After three years through five years	120
Debt securities, Available-for-sale, Amortized cost, After five years through ten years	78,994
Debt securities, Available-for-sale, Amortized cost, After ten years	238,154
Debt securities, Available-for-sale, Estimated fair value, After one year through three years
Debt securities, Available-for-sale, Estimated fair value, After three years through five years	122
Debt securities, Available-for-sale, Estimated fair value, After five years through ten years	81,182
Debt securities, Available-for-sale, Estimated fair value, After ten years	238,683
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	59,462
Debt securities, Held-to-maturity, Amortized cost, After ten years	885,532
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	61,719
Debt securities, Held-to-maturity, Estimated fair value, After ten years	$ 918,399