INVESTMENTS (Amortized Cost and Estimated Fair Values of investment securities Available-For-Sale by Contractual Maturity) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amortized Cost
Due in one year or less	$ 63,482	$ 12,789
Due after one year through five years	277,297	180,109
Due after five years through ten years	212,825	228,484
Due after ten years	392,136	306,771
Total debt securities available for sale	945,740	728,153
Estimated Fair Value
Due in one year or less	63,747	12,889
Due after one year through five years	276,830	184,264
Due after five years through ten years	210,386	227,688
Due after ten years	385,804	304,454
Estimated Fair Value	$ 936,767	$ 729,295