Investment Securities (Amortized Cost And Estimated Fair Value Of Investments In Debt Securities By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2011	Dec. 31, 2010
Schedule of Investments [Line Items]
Securities Available-for-Sale, Fair Value	$ 1,117,397	$ 1,297,522
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Due within one year, Amortized cost	211,965
Securities Available-for-Sale, Due within one year, Fair value	213,429
Securities Available-for-Sale, Due one through five years, Amortized cost
Securities Available-for-Sale, Due one through five years, Fair value
Securities Available-for-Sale, Due five through ten years, Amortized cost	96,335
Securities Available-for-Sale, Due five through ten years, Fair value	95,226
Securities Available-for-Sale, Total, Amortized cost	308,300
Securities Available-for-Sale, Fair Value	308,655	273,313
Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Due within one year, Amortized cost	3,695
Securities Available-for-Sale, Due within one year, Fair value	3,712
Securities Available-for-Sale, Due one through five years, Amortized cost	1,301
Securities Available-for-Sale, Due one through five years, Fair value	1,397
Securities Available-for-Sale, Total, Amortized cost	4,996
Securities Available-for-Sale, Fair Value	5,109	11,044
Securities Held-to-Maturity, Due within one year, Amortized cost	2,077
Securities Held-to-Maturity, Due within one year, Fair value	2,082
Securities Held-to-Maturity, Total, Amortized cost	2,077
Securities Held-to-Maturity, Total, Fair value	2,082
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total, Amortized cost	792,977
Securities Available-for-Sale, Fair Value	801,924	1,011,412
Securities Held-to-Maturity, Total, Amortized cost	773,234
Securities Held-to-Maturity, Total, Fair value	$ 784,140