SECURITIES (Amortized Cost And Estimated Fair Values Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 2,436,449	$ 2,122,249	$ 2,059,445
Gross Unrealized Gains	34,947	39,216	28,855
Gross Unrealized Losses	3,197	340	5,971
Estimated Fair Value	2,468,199	2,161,125	2,082,329
Gross gains recognized on available-for-sale securities	89	88
US Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,686,637	1,249,043	1,246,261
Gross Unrealized Gains	5,330	6,674	826
Gross Unrealized Losses	101		2,447
Estimated Fair Value	1,691,866	1,255,717	1,244,640
U.S. Government Agency Issued Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	181,307	203,852	138,759
Gross Unrealized Gains	2,887	3,301	1,957
Gross Unrealized Losses	99	275	176
Estimated Fair Value	184,095	206,878	140,540
U.S. Government Agency Issued Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	175,078	226,285	261,544
Gross Unrealized Gains	3,831	3,661	2,414
Gross Unrealized Losses	82	24	3,265
Estimated Fair Value	178,827	229,922	260,693
Obligations Of States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	366,039	426,911	394,769
Gross Unrealized Gains	21,871	24,730	22,813
Gross Unrealized Losses	2,915	41	83
Estimated Fair Value	384,995	451,600	417,499
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	27,388	16,158	18,112
Gross Unrealized Gains	1,028	850	845
Estimated Fair Value	$ 28,416	$ 17,008	$ 18,957