INVESTMENT SECURITIES - Contractual Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities available for sale:
Due in one year or less, Amortized cost	$ 29,054	$ 66,591
Due from one to five years, Amortized cost	618,764	291,298
Due from five to ten years, Amortized cost	294,137	309,625
Due after ten years, Amortized cost	56,008	24,616
Equity Securities, Amortized cost	8,929	2,381
Amortized Cost	1,006,892	694,511
Due in one year or less, Fair value	29,122	67,163
Due from one to five years, Fair value	610,709	289,525
Due from five to ten years, Fair value	286,919	306,420
Due after ten years, Fair value	55,189	24,398
Equity Securities, Fair value	8,674	1,626
Fair Value	990,613	689,132
Securities held to maturity:
Due after one year through five years, Amortized Cost	29,928	31,421
Due after five years through ten years, Amortized Cost	4,028	4,072
Due after ten years, Amortized Cost	3,774	3,689
Amortized Cost	37,730	39,182
Due after one year through five years, Fair Value	30,399	32,272
Due after five years through ten years, Fair Value	4,076	4,229
Due after ten years, Fair Value	3,978	3,999
Fair Value	$ 38,453	$ 40,500