SECURITIES - Securities in Continuous Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	$ 487,436	$ 587,315
Gross Unrealized Losses, Less than 12 Months	(14,210)	(9,756)
Fair Value, Less than 12 Months	473,226	577,559
Amortized Cost, More than 12 Months	156,412	29,526
Gross Unrealized Losses, More than 12 Months	(6,127)	(643)
Fair Value, More than 12 Months	150,285	28,883
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	55,103	3,520
Gross Unrealized Losses, Less than 12 Months	(311)	(29)
Fair Value, Less than 12 Months	54,792	3,491
Amortized Cost, More than 12 Months	6,017	6,265
Gross Unrealized Losses, More than 12 Months	(311)	(161)
Fair Value, More than 12 Months	5,706	6,104
SBA guaranteed securities
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	89,688	76,603
Gross Unrealized Losses, Less than 12 Months	(1,892)	(948)
Fair Value, Less than 12 Months	87,796	75,655
Amortized Cost, More than 12 Months	4,979
Gross Unrealized Losses, More than 12 Months	(90)
Fair Value, More than 12 Months	4,889
Mortgage-backed securities issued by U.S. government agencies or sponsored enterprises: residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	227,164	192,105
Gross Unrealized Losses, Less than 12 Months	(7,095)	(1,608)
Fair Value, Less than 12 Months	220,069	190,497
Amortized Cost, More than 12 Months		9,152
Gross Unrealized Losses, More than 12 Months		(93)
Fair Value, More than 12 Months		9,059
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	3,893	1,086
Gross Unrealized Losses, Less than 12 Months	(78)	(9)
Fair Value, Less than 12 Months	3,815	1,077
Amortized Cost, More than 12 Months	6,017	6,265
Gross Unrealized Losses, More than 12 Months	(311)	(161)
Fair Value, More than 12 Months	5,706	6,104
Mortgage-backed securities issued by U.S. government agencies or sponsored enterprises: commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	52,887	65,986
Gross Unrealized Losses, Less than 12 Months	(2,340)	(500)
Fair Value, Less than 12 Months	50,547	65,486
Amortized Cost, More than 12 Months	12,936
Gross Unrealized Losses, More than 12 Months	(483)
Fair Value, More than 12 Months	12,453
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	2,488
Gross Unrealized Losses, Less than 12 Months	(90)
Fair Value, Less than 12 Months	2,398
Collateralized mortgage obligations issued by U.S. government agencies or sponsored enterprises: residential
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	72,794	210,034
Gross Unrealized Losses, Less than 12 Months	(1,481)	(6,183)
Fair Value, Less than 12 Months	71,313	203,851
Amortized Cost, More than 12 Months	138,497	9,037
Gross Unrealized Losses, More than 12 Months	(5,554)	(251)
Fair Value, More than 12 Months	132,943	8,786
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	42,531	2,434
Gross Unrealized Losses, Less than 12 Months	(138)	(20)
Fair Value, Less than 12 Months	42,393	2,414
Collateralized mortgage obligations issued by U.S. government agencies or sponsored enterprises: commercial
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	35,990	36,151
Gross Unrealized Losses, Less than 12 Months	(1,341)	(472)
Fair Value, Less than 12 Months	34,649	35,679
Corporate debt securities
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	8,913
Gross Unrealized Losses, Less than 12 Months	(61)
Fair Value, Less than 12 Months	8,852
Municipal bonds
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months		6,436
Gross Unrealized Losses, Less than 12 Months		(45)
Fair Value, Less than 12 Months		6,391
Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, Less than 12 Months	6,191
Gross Unrealized Losses, Less than 12 Months	(5)
Fair Value, Less than 12 Months	$ 6,186
CRA qualified investment fund
Available-for-sale, Continuous Unrealized Loss Position [Abstract]
Amortized Cost, More than 12 Months		11,337
Gross Unrealized Losses, More than 12 Months		(299)
Fair Value, More than 12 Months		$ 11,038