SECURITIES (Schedule of Carrying Value, Gross Unrealized Gains and Losses and Estimated Fair Value of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	$ 552,176	$ 555,144
Gross Unrealized Gains	52,815	48,359
Gross Unrealized Losses	(211)	0
Held-to-maturity Securities, Fair Value	604,780	603,503
U.S. government and agency securities
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	2,797	2,813
Gross Unrealized Gains	0	26
Gross Unrealized Losses	(69)	0
Held-to-maturity Securities, Fair Value	2,728	2,839
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	543,517	545,148
Gross Unrealized Gains	52,815	48,274
Gross Unrealized Losses	0	0
Held-to-maturity Securities, Fair Value	596,332	593,422
Total mortgage-back securities
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	5,862	7,183
Gross Unrealized Gains	0	59
Gross Unrealized Losses	(142)	0
Held-to-maturity Securities, Fair Value	5,720	7,242
Commercial
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	5,862	7,183
Gross Unrealized Gains	0	59
Gross Unrealized Losses	(142)	0
Held-to-maturity Securities, Fair Value	5,720	7,242
Residential
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	0	0
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Held-to-maturity Securities, Fair Value	$ 0	$ 0