SECURITIES (Schedule of Carrying Value, Gross Unrealized Gains and Losses and Estimated Fair Value of Securities) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Jun. 30, 2015	Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]
Total securities held to maturity	$ 198,733		$ 199,639
Estimated Fair Value	199,904		203,483
Held to maturity securities unrealized gains before tax	3,200	$ 8,100	3,600
Obligations of States and Political Subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Total securities held to maturity	198,733		199,639
Gross Unrealized Gains	1,540		4,014
Gross Unrealized (Losses)	(369)		(170)
Estimated Fair Value	$ 199,904		$ 203,483