Investment Securities (Schedule Of Amortized Cost And Fair Value By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011	Sep. 30, 2011
Schedule of Investments [Line Items]
Within 1 year, Amortized Cost	$ 54,995
After 1 year; within 5 years, Amortized Cost	5,411
After 5 years; within 10 years, Amortized Cost	0
After 10 years, Amortized Cost	16,470
Subtotal, Amortized Cost	76,876
Within 1 year, Fair Value	54,996
After 1 year; within 5 years, Fair Value	5,702
After 5 years; within 10 years, Fair Value	0
After 10 years, Fair Value	16,470
Subtotal, Fair Value	77,168
Securities available for sale, Amortized Cost	3,019,009	[1]		3,197,965	[2]
Securities available for sale, Fair Value	3,123,629	[1]	3,066,272	3,327,846	[2]
Government Agency Issued Mbs And Cmo [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	2,721,886
Securities available for sale, Fair Value	2,826,191
Equity Securities Other [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	220,247
Securities available for sale, Fair Value	$ 220,270

[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, $.6 billion was pledged as collateral for securities sold under repurchase agreements.

[2] Includes $3.0 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.