SECURITIES (Temporarily Impaired Available-For-Sale Securities With Continuous Unrealized Loss Positions) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 1,609,995	$ 1,330,910
12 Months or Longer, Fair Value	21,037	29,760
Total, Fair Value	1,631,032	1,360,670
Less Than 12 Months, Unrealized Losses	9,679	11,083
12 Months or Longer, Unrealized Losses	266	240
Total, Unrealized Losses	9,945	11,323
US Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,381,118	1,082,573
Total, Fair Value	1,381,118	1,082,573
Less Than 12 Months, Unrealized Losses	5,944	6,065
Total, Unrealized Losses	5,944	6,065
U.S. Government Agency Issued Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	83,628	71,599
12 Months or Longer, Fair Value	7,443	15,375
Total, Fair Value	91,071	86,974
Less Than 12 Months, Unrealized Losses	1,467	1,783
12 Months or Longer, Unrealized Losses	159	115
Total, Unrealized Losses	1,626	1,898
U.S. Government Agency Issued Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	124,824	129,940
12 Months or Longer, Fair Value	13,594	14,385
Total, Fair Value	138,418	144,325
Less Than 12 Months, Unrealized Losses	937	1,084
12 Months or Longer, Unrealized Losses	107	125
Total, Unrealized Losses	1,044	1,209
Obligations Of States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	20,425	46,798
Total, Fair Value	20,425	46,798
Less Than 12 Months, Unrealized Losses	1,331	2,151
Total, Unrealized Losses	$ 1,331	$ 2,151