INVESTMENTS (Amortized Cost and Estimated Fair Values of investment securities Available-For-Sale by Contractual Maturity) (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Amortized Cost
Due in one year or less	$ 87,362	$ 63,482
Due after one year through five years	212,317	277,297
Due after five years through ten years	161,457	212,825
Due after ten years	424,668	392,136
Total debt securities available for sale	885,804	945,740
Estimated Fair Value
Due in one year or less	87,981	63,747
Due after one year through five years	214,443	276,830
Due after five years through ten years	164,716	210,386
Due after ten years	426,564	385,804
Estimated Fair Value	$ 893,704	$ 936,767