Investment Securities (Schedule Of Maturities Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Investment Securities [Abstract]
Available-for-sale Securities, Three months or less, Amortized Cost	$ 41,686
Available-for-sale Securities, Over three months through twelve months, Amortized Cost	385,395
Available-for-sale Securities, After one year through five years, Amortized Cost	1,551,960
Available-for-sale Securities, After five years through ten years, Amortized Cost	402,606
Available-for-sale Securities, After ten years, Amortized Cost	200,858
Available-for-sale Securities, Other investment securities, Amortized Cost	1,959
Available-for-sale Securities, Amortized Cost	2,584,464
Available-for-sale Securities, Three months or less, Fair Value	41,617
Available-for-sale Securities, Over three months through twelve months, Fair Value	388,761
Available-for-sale Securities, After one year through five years, Fair Value	1,577,761
Available-for-sale Securities, After five years through ten years, Fair Value	412,081
Available-for-sale Securities, After ten years, Fair Value	202,923
Available-for-sale Securities, Other investment securities, Fair Value	2,086
Available-for-sale Securities, Fair Value	2,625,229
Held-to-maturity Securities, Three months or less, Amortized Cost	245
Held-to-maturity Securities, Over three months through twelve months, Amortized Cost	350
Held-to-maturity Securities, After one year through five years, Amortized Cost	1,157
Held-to-maturity Securities, After five years through ten years, Amortized Cost	227
Held-to-maturity Securities, After ten years, Amortized Cost	2,562
Held-to-maturity Securities, Other investment securities, Amortized Cost
Held-to-maturity Securities, Amortized Cost	4,541
Held-to-maturity Securities, Three months or less, Fair Value	245
Held-to-maturity Securities, Over three months through twelve months, Fair Value	351
Held-to-maturity Securities, After one year through five years, Fair Value	1,289
Held-to-maturity Securities, After five years through ten years, Fair Value	285
Held-to-maturity Securities, After ten years, Fair Value	2,562
Held-to-maturity Securities, Other investment securities, Fair Value
Held-to-maturity Securities, Fair Value	$ 4,732