INVESTMENTS (Amortized Cost and Estimated Fair Values of investment securities Available-For-Sale by Contractual Maturity) (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less	$ 5,310	$ 7,493
Due after one year through five years	162,299	156,953
Due after five years through ten years	289,294	282,468
Due after ten years	351,761	282,708
Total debt securities available for sale	808,664	729,622
Estimated Fair Value
Due in one year or less	5,348	7,541
Due after one year through five years	168,435	162,233
Due after five years through ten years	289,884	282,713
Due after ten years	349,206	279,844
Estimated Fair Value	$ 812,873	$ 732,331