SECURITIES (Schedule of Amortized Cost and Estimated Fair Values of Debt Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Available-for-sale, Amortized Cost
Due in one year or less	$ 1,440
Due after one year through five years	105,688
Due after five years through ten years	101,074
Due after ten years	569,901
Amortized cost, total	778,103
Available-for-sale, Fair Value
Due in one year or less	1,442
Due after one year through five years	107,064
Due after five years through ten years	104,023
Due after ten years	575,701
Fair value, total	788,230
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis [Abstract]
Due after one year through five years	2,943
Due after five years through ten years	5,435
Due after ten years	85,827
Held-to-maturity securities, at amortized cost	94,205	$ 84,144
Held-to-maturity Securities, Debt Maturities, Single Maturity Date, Fair Value [Abstract]
Due after one year through five years	3,002
Due after five years through ten years	5,624
Due after ten years	89,470
Held-to-maturity Securities, Fair Value	$ 98,096	$ 85,647