Investment Securities (Schedule Of Amortized Cost And Fair Value By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011	Jun. 30, 2011
Schedule of Investments [Line Items]
Within 1 year, Amortized Cost	$ 48,467
After 1 year; within 5 years, Amortized Cost	5,841
After 5 years; within 10 years, Amortized Cost	0
After 10 years, Amortized Cost	16,470
Subtotal, Amortized Cost	70,778
Within 1 year, Fair Value	48,488
After 1 year; within 5 years, Fair Value	6,161
After 5 years; within 10 years, Fair Value	0
After 10 years, Fair Value	16,470
Subtotal, Fair Value	71,119
Securities available for sale, Amortized Cost	3,160,646	[1]		3,135,438	[2]
Securities available for sale, Fair Value	3,264,866	[1]	3,066,272	3,230,477	[2]
Government Agency Issued MBS And CMO [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	2,869,234
Securities available for sale, Fair Value	2,973,100
Equity And Other Securities [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	220,634
Securities available for sale, Fair Value	$ 220,647

[1] Includes $3.0 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $.5 billion was pledged as collateral for securities sold under repurchase agreements.

[2] Includes $2.9 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes. Of this amount, $1.1 billion was pledged as collateral for securities sold under repurchase agreements.