Investment Securities (Schedule Of Maturities Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Investment Holdings [Line Items]
Available-for-sale Securities, Three months or less, Amortized Cost	$ 73,106
Available-for-sale Securities, Over three months through twelve months, Amortized Cost	348,163
Available-for-sale Securities, After one year through five years, Amortized Cost	1,442,344
Available-for-sale Securities, After five years through ten years, Amortized Cost	400,317
Available-for-sale Securities, After ten years, Amortized Cost	94,397
Available-for-sale Securities, Amortized Cost	2,360,286
Available-for-sale Securities, Three months or less, Fair Value	73,295
Available-for-sale Securities, Over three months through twelve months, Fair Value	351,017
Available-for-sale Securities, After one year through five years, Fair Value	1,467,309
Available-for-sale Securities, After five years through ten years, Fair Value	406,476
Available-for-sale Securities, After ten years, Fair Value	96,449
Available-for-sale Securities, Fair Value	2,396,617
Held-to-maturity Securities, Three months or less, Amortized Cost	350
Held-to-maturity Securities, Over three months through twelve months, Amortized Cost	0
Held-to-maturity Securities, After one year through five years, Amortized Cost	940
Held-to-maturity Securities, After five years through ten years, Amortized Cost	401
Held-to-maturity Securities, After ten years, Amortized Cost	2,498
Held-to-maturity Securities, Amortized Cost	4,189
Held-to-maturity Securities, Three months or less, Fair Value	351
Held-to-maturity Securities, Over three months through twelve months, Fair Value	0
Held-to-maturity Securities, After one year through five years, Fair Value	1,117
Held-to-maturity Securities, After five years through ten years, Fair Value	393
Held-to-maturity Securities, After ten years, Fair Value	2,500
Held-to-maturity Securities, Fair Value	4,361
Other Investments Securities [Member]
Investment Holdings [Line Items]
Available-for-sale Securities, Amortized Cost	1,959
Available-for-sale Securities, Fair Value	2,071
Held-to-maturity Securities, Amortized Cost	0
Held-to-maturity Securities, Fair Value	$ 0