Investment Securities (Amortized Cost And Estimated Fair Value Of Investments In Debt Securities By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total Fair value	$ 1,129,483	$ 1,114,454
Securities Held-to-Maturity, Amortized Cost	193,997	401,390
Securities held-to-maturity, fair value	199,941	410,705
Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Due within one year, Amortized cost	220
Securities Available-for-Sale, Due within one year, Fair value	221
Securities Available-for-Sale, Total Fair value	221	1,003
Securities Held-to-Maturity, Due within one year, Amortized cost	240
Securities Held-to-Maturity, Due within one year, Fair value	241
Securities Held-to-Maturity, Amortized Cost	240	570
Securities held-to-maturity, fair value	241	572
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	25,000
Securities Available-for-Sale, Due within one year, Fair value	25,115
Securities Available-for-Sale, Due one through five years, Amortized cost	100,000
Securities Available-for-Sale, Due one through five years, Fair value	96,715
Securities Available-for-Sale, Due five through ten years, Amortized cost	396,881
Securities Available-for-Sale, Due five through ten years, Fair value	372,909
Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis	123,750
Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value	111,006
Securities Available-for-Sale, Total, Amortized cost	645,631
Securities Available-for-Sale, Total Fair value	605,745	695,727
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total, Amortized cost	519,917
Securities Available-for-Sale, Total Fair value	521,025	415,502
Securities Held-to-Maturity, Amortized Cost	193,757	400,820
Securities held-to-maturity, fair value	$ 199,700	$ 410,133