Investment Securities (Schedule Of Maturities Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Available-for-sale Securities, Three months or less, Amortized Cost	$ 22,142
Available-for-sale Securities, Over three months through twelve months, Amortized Cost	424,824
Available-for-sale Securities, After one through five Years, Amortized Cost	2,272,876
Available-for-sale Securities, After five through ten years, Amortized Cost	310,639
Available-for-sale Securities, After ten years, Amortized Cost	79,357
Available-for-sale Securities, Amortized Cost	3,111,797
Available-for-sale Securities, Three months or less, Fair Value	22,217
Available-for-sale Securities, Over three months through twelve months, Fair Value	429,396
Available-for-sale Securities, After one through five years, Fair Value	2,310,113
Available-for-sale Securities, After five through ten years, Fair Value	323,164
Available-for-sale Securities, After ten years, Fair Value	81,617
Available-for-sale Securities, Fair Value	3,168,578
Held-to-maturity Securities, Over three months through twelve months, Amortized Cost	330
Held-to-maturity Securities, After one through five years, Amortized Cost	1,096
Held-to-maturity Securities, After five through ten years, Amortized Cost	1,023
Held-to-maturity Securities, After ten years, Amortized Cost	2,265
Held-to-maturity Securities, Amortized Cost	4,714
Held-to-maturity Securities, Over three months through twelve months, Fair Value	331
Held-to-maturity Securities, After one through five years, Fair Value	1,155
Held-to-maturity Securities, After five through ten years, Fair Value	1,010
Held-to-maturity Securities, After ten years, Fair Value	2,263
Held-to-maturity Securities, Fair Value	4,759
Other Investments Securities [Member]
Available-for-sale Securities, Amortized Cost	1,959
Available-for-sale Securities, Fair Value	$ 2,071