INVESTMENTS (Amortized Cost and Estimated Fair Values of investment securities Available-For-Sale by Contractual Maturity) (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 64,147	$ 63,482
Due after one year through five years	278,728	277,297
Due after five years through ten years	172,732	212,825
Due after ten years	377,847	392,136
Total debt securities available for sale	893,454	945,740
Estimated Fair Value
Due in one year or less	64,455	63,747
Due after one year through five years	281,339	276,830
Due after five years through ten years	175,655	210,386
Due after ten years	379,008	385,804
Estimated Fair Value	$ 900,457	$ 936,767