SECURITIES (Schedule of Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Available-for-sale, Amortized Cost
Due in one year or less	$ 1,631
Due after one year through five years	103,620
Due after five years through ten years	162,740
Due after ten years	548,950
Amortized cost, total	816,941
Available-for-sale, Fair Value
Due in one year or less	1,639
Due after one year through five years	103,833
Due after five years through ten years	162,857
Due after ten years	541,287
Fair value, total	809,616
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Due in one year or less	758
Due after one year through five years	4,769
Due after five years through ten years	5,043
Due after ten years	83,770
Held-to-maturity securities, at amortized cost	94,340	$ 94,609
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Due in one year or less	762
Due after one year through five years	4,835
Due after five years through ten years	5,140
Due after ten years	84,271
Held-to-maturity Securities, Fair Value	$ 95,008	$ 94,596