SECURITIES (Temporarily Impaired Available-For-Sale Securities With Continuous Unrealized Loss Positions) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 1,562,542	$ 1,330,910
12 Months or Longer, Fair Value	19,240	29,760
Total, Fair Value	1,581,782	1,360,670
Less Than 12 Months, Unrealized Losses	10,485	11,083
12 Months or Longer, Unrealized Losses	211	240
Total, Unrealized Losses	10,696	11,323
US Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,319,456	1,082,573
Total, Fair Value	1,319,456	1,082,573
Less Than 12 Months, Unrealized Losses	5,975	6,065
Total, Unrealized Losses	5,975	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	88,596	71,599
12 Months or Longer, Fair Value	5,578	15,375
Total, Fair Value	94,174	86,974
Less Than 12 Months, Unrealized Losses	1,751	1,783
12 Months or Longer, Unrealized Losses	82	115
Total, Unrealized Losses	1,833	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	128,763	129,940
12 Months or Longer, Fair Value	13,662	14,385
Total, Fair Value	142,425	144,325
Less Than 12 Months, Unrealized Losses	1,295	1,084
12 Months or Longer, Unrealized Losses	129	125
Total, Unrealized Losses	1,424	1,209
Obligations Of States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	25,727	46,798
Total, Fair Value	25,727	46,798
Less Than 12 Months, Unrealized Losses	1,464	2,151
Total, Unrealized Losses	$ 1,464	$ 2,151