Investment Securities (Schedule Of Amortized Cost And Fair Value By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011	Mar. 31, 2011
Schedule of Investments [Line Items]
Within 1 year, Amortized Cost	$ 49,366
After 1 year; within 5 years, Amortized Cost	6,265
After 5 years; within 10 years, Amortized Cost
After 10 years, Amortized Cost	16,570
Subtotal, Amortized Cost	72,201
Within 1 year, Fair Value	49,489
After 1 year; within 5 years, Fair Value	6,594
After 5 years; within 10 years, Fair Value
After 10 years, Fair Value	16,570
Subtotal, Fair Value	72,653
Securities available for sale, Amortized Cost	3,186,822	[1]		3,021,095	[2]
Securities available for sale, Fair Value	3,296,603	[1]	3,066,272	3,085,478	[2]
Government Agency Issued MBS And CMO [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	2,890,560
Securities available for sale, Fair Value	2,999,866
Equity And Other Securities [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	224,061
Securities available for sale, Fair Value	$ 224,084

[1] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $.4 billion was pledged as collateral for securities sold under repurchase agreements.

[2] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $.9 bilion was pledged as collateral for securities sold under repurchase agreements.