SECURITIES - Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Securities in a continuous unrealized loss position with unrealized losses presented by length of time
Less than 12 months, Fair Value	$ 356,322	$ 509,184
Less than 12 months, Unrealized Losses	(3,740)	(8,679)
12 months or longer, Fair Value	36,444	8,518
12 months or longer, Unrealized Losses	(1,128)	(225)
Total Fair Value	392,766	517,702
Total Unrealized Losses	(4,868)	(8,904)
State and municipal
Securities in a continuous unrealized loss position with unrealized losses presented by length of time
Less than 12 months, Fair Value	36,363	95,822
Less than 12 months, Unrealized Losses	(517)	(2,848)
12 months or longer, Fair Value	10,073
12 months or longer, Unrealized Losses	(380)
Total Fair Value	46,436	95,822
Total Unrealized Losses	(897)	(2,848)
Mortgage-backed securities-residential (Government Sponsored Entity)
Securities in a continuous unrealized loss position with unrealized losses presented by length of time
Less than 12 months, Fair Value	187,075	335,668
Less than 12 months, Unrealized Losses	(2,359)	(4,629)
12 months or longer, Fair Value	8,791
12 months or longer, Unrealized Losses	(233)
Total Fair Value	195,866	335,668
Total Unrealized Losses	(2,592)	(4,629)
Collateralized mortgage obligations (Government Sponsored Entity)
Securities in a continuous unrealized loss position with unrealized losses presented by length of time
Less than 12 months, Fair Value	132,884	77,694
Less than 12 months, Unrealized Losses	(864)	(1,202)
12 months or longer, Fair Value	17,580	8,518
12 months or longer, Unrealized Losses	(515)	(225)
Total Fair Value	150,464	86,212
Total Unrealized Losses	$ (1,379)	$ (1,427)