Investment Securities (Schedule Of Investment Securities) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	$ 1,277,358	$ 1,222,143
Securities Available-for-Sale, Gross Unrealized Holdings Gains	12,009	9,609
Securities Available-for-Sale, Gross Unrealized Holding Losses	25,402	55,486
Securities Available-for-Sale, Total Fair value	1,263,965	1,176,266
Securities Held-to-Maturity, Amortized Cost	150,349	182,061
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	3,099	5,383
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	462	42
Securities Held-to-Maturity, Estimated Fair Value	152,986	187,402
Obligations Of U.S. Treasury And Other U.S. Government Sponsored Entities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	570,635	570,632
Securities Available-for-Sale, Gross Unrealized Holdings Gains
Securities Available-for-Sale, Gross Unrealized Holding Losses	19,476	45,496
Securities Available-for-Sale, Total Fair value	551,159	525,136
Obligations Of States And Political Subdivisions [Member]
Schedule of Investments [Line Items]
Securities Held-to-Maturity, Amortized Cost		240
Securities Held-to-Maturity, Gross Unrecognized Holding Gains		1
Securities Held-to-Maturity, Gross Unrecognized Holding Losses
Securities Held-to-Maturity, Estimated Fair Value		241
U.S. Government Sponsored Entities Asset-Backed Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	705,603	650,391
Securities Available-for-Sale, Gross Unrealized Holdings Gains	10,544	8,070
Securities Available-for-Sale, Gross Unrealized Holding Losses	5,926	9,990
Securities Available-for-Sale, Total Fair value	710,221	648,471
Securities Held-to-Maturity, Amortized Cost	150,349	181,821
Securities Held-to-Maturity, Gross Unrecognized Holding Gains	3,099	5,382
Securities Held-to-Maturity, Gross Unrecognized Holding Losses	462	42
Securities Held-to-Maturity, Estimated Fair Value	152,986	187,161
Other Equity Securities [Member]
Schedule of Investments [Line Items]
Securities Available-for-Sale, Amortized Cost	1,120	1,120
Securities Available-for-Sale, Gross Unrealized Holdings Gains	1,465	1,539
Securities Available-for-Sale, Gross Unrealized Holding Losses
Securities Available-for-Sale, Total Fair value	$ 2,585	$ 2,659