FAIR VALUE - Gross unrealized losses and fair value, aggregated by investment category and length of time that individual securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	$ 40,326	$ 20,188
Less than 12 months Unrealized Loss	(878)	(198)
12 months or more Fair Value	38,195	40,641
12 months or more Unrealized Loss	(1,736)	(1,084)
Total Fair Value	78,521	60,829
Total Unrealized Loss	(2,614)	(1,282)
Residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	14,707	13,333
Less than 12 months Unrealized Loss	(402)	(143)
12 months or more Fair Value	31,610	33,896
12 months or more Unrealized Loss	(1,456)	(927)
Total Fair Value	46,317	47,229
Total Unrealized Loss	(1,858)	(1,070)
Municipal securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	17,903	2,396
Less than 12 months Unrealized Loss	(336)	(11)
12 months or more Fair Value	6,079	6,230
12 months or more Unrealized Loss	(271)	(148)
Total Fair Value	23,982	8,626
Total Unrealized Loss	(607)	(159)
U.S. Government agency securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	6,230	2,965
Less than 12 months Unrealized Loss	(125)	(37)
12 months or more Fair Value	506	515
12 months or more Unrealized Loss	(9)	(9)
Total Fair Value	6,736	3,480
Total Unrealized Loss	(134)	(46)
U.S. Treasury securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months Fair Value	1,486	1,494
Less than 12 months Unrealized Loss	(15)	(7)
Total Fair Value	1,486	1,494
Total Unrealized Loss	$ (15)	$ (7)