SECURITIES (Schedule of Carrying Value, Gross Unrealized Gains and Losses and Estimated Fair Value of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule of Held-to-maturity Securities [Line Items]
Total HTM securities	$ 559,380	$ 492,272
Gross Unrealized Gains	25,226
Gross Unrealized (Losses)	0
Estimated Fair Value	584,606	499,501
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total HTM securities	548,383	492,272
Gross Unrealized Gains	25,179	7,375
Gross Unrealized (Losses)	0	(146)
Estimated Fair Value	573,562	$ 499,501
Mortgage-backed securities
Schedule of Held-to-maturity Securities [Line Items]
Total HTM securities	10,997
Gross Unrealized Gains	47
Gross Unrealized (Losses)	0
Estimated Fair Value	$ 11,044