SECURITIES (Schedule of Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale, Amortized Cost
Due in one year or less	$ 1,585
Due after one year through five years	88,748
Due after five years through ten years	170,189
Due after ten years	572,153
Amortized cost, total	832,675
Available-for-sale, Fair Value
Due in one year or less	1,587
Due after one year through five years	88,607
Due after five years through ten years	169,920
Due after ten years	562,351
Fair value, total	822,465
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Due in one year or less	762
Due after one year through five years	4,801
Due after five years through ten years	4,561
Due after ten years	84,350
Held-to-maturity securities, at amortized cost	94,474	$ 94,609
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Due in one year or less	768
Due after one year through five years	4,870
Due after five years through ten years	4,622
Due after ten years	84,084
Held-to-maturity Securities, Fair Value	$ 94,344	$ 94,596