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, 2013	Dec. 31, 2012
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total Fair value	$ 1,047,375	$ 1,114,454
Securities Held-to-Maturity, Amortized Cost	231,787	401,390
Securities held-to-maturity, fair value	238,519	410,705
Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Due within one year, Amortized cost	804
Securities Available-for-Sale, Due within one year, Fair value	809
Securities Available-for-Sale, Total Fair value	809	1,003
Securities Held-to-Maturity, Due within one year, Amortized cost	415
Securities Held-to-Maturity, Due within one year, Fair value	416
Securities Held-to-Maturity, Amortized Cost	415	570
Securities held-to-maturity, fair value	416	572
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Due one through five years, Amortized cost	223,750
Securities Available-for-Sale, Due one through five years, Fair value	216,659
Securities Available-for-Sale, Due five through ten years, Amortized cost	396,890
Securities Available-for-Sale, Due five through ten years, Fair value	378,073
Securities Available-for-Sale, Total, Amortized cost	620,640
Securities Available-for-Sale, Total Fair value	594,732	695,727
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Total, Amortized cost	445,254
Securities Available-for-Sale, Total Fair value	449,282	415,502
Securities Held-to-Maturity, Amortized Cost	231,372	400,820
Securities held-to-maturity, fair value	$ 238,103	$ 410,133