SECURITIES (Schedule of Carrying Value, Gross Unrealized Gains and Losses and Estimated Fair Value of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	$ 543,575	$ 544,851
Gross Unrealized Gains	62,881	74,982
Gross Unrealized Losses	(97)	(68)
Held-to-maturity Securities, Fair Value	606,359	619,765
U.S. government and agency securities
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	2,676	2,751
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(31)	(18)
Held-to-maturity Securities, Fair Value	2,645	2,733
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	535,634	536,767
Gross Unrealized Gains	62,880	74,978
Gross Unrealized Losses	0	0
Held-to-maturity Securities, Fair Value	598,514	611,745
Commercial
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	5,265	5,333
Gross Unrealized Gains	1	4
Gross Unrealized Losses	(66)	(50)
Held-to-maturity Securities, Fair Value	5,200	5,287
Agency | Commercial
Schedule of Held-to-maturity Securities [Line Items]
Total HTM Securities	5,265	5,333
Gross Unrealized Gains	1	4
Gross Unrealized Losses	(66)	(50)
Held-to-maturity Securities, Fair Value	5,200	5,287
Non-agency | Commercial
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