Investment Securities (Schedule Of Amortized Cost And Fair Value By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012	Mar. 31, 2012
Schedule of Investments [Line Items]
Within 1 year, Amortized Cost	$ 39,992
After 1 year; within 5 years, Amortized Cost	4,568
After 5 years; within 10 years, Amortized Cost	0
After 10 years, Amortized Cost	13,755
Subtotal, Amortized Cost	58,315
Within 1 year, Fair Value	39,994
After 1 year; within 5 years, Fair Value	4,776
After 5 years; within 10 years, Fair Value	0
After 10 years, Fair Value	13,755
Subtotal, Fair Value	58,525
Securities available for sale, Amortized Cost	3,110,692	[1]		3,186,822	[2]
Securities available for sale, Fair Value	3,190,219	[1]	3,061,808	3,296,603	[2]
Government Agency Issued Mbs And Cmo [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	2,835,597
Securities available for sale, Fair Value	2,914,904
Equity Securities Other [Member]
Schedule of Investments [Line Items]
Securities available for sale, Amortized Cost	216,780
Securities available for sale, Fair Value	$ 216,790

[1] Includes $2.9 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes.

[2] Includes $2.8 billion of securities pledged to secure public deposits, securities sold under agreements to repurchase, and for other purposes.