SECURITIES - Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 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	$ 357,172	$ 509,184
Less than 12 months, Unrealized Losses	(5,365)	(8,679)
12 months or longer, Fair Value	8,268	8,518
12 months or longer, Unrealized Losses	(234)	(225)
Total Fair Value	365,440	517,702
Total Unrealized Losses	(5,599)	(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	49,178	95,822
Less than 12 months, Unrealized Losses	(1,164)	(2,848)
12 months or longer, Fair Value	467
12 months or longer, Unrealized Losses	(30)
Total Fair Value	49,645	95,822
Total Unrealized Losses	(1,194)	(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	227,307	335,668
Less than 12 months, Unrealized Losses	(3,296)	(4,629)
Total Fair Value	227,307	335,668
Total Unrealized Losses	(3,296)	(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	80,687	77,694
Less than 12 months, Unrealized Losses	(905)	(1,202)
12 months or longer, Fair Value	7,801	8,518
12 months or longer, Unrealized Losses	(204)	(225)
Total Fair Value	88,488	86,212
Total Unrealized Losses	$ (1,109)	$ (1,427)