SECURITIES AVAILABLE FOR SALE - Summary of Securities with Unrealized Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Gross Unrealized Losses
Less Than Twelve Months	$ 2,565	$ 8,093
Over Twelve Months	5,212	803
Total	7,777	8,896
Fair Value
Less Than Twelve Months	251,956	311,765
Over Twelve Months	175,168	18,611
Total	427,124	330,376
US Government-sponsored enterprises
Gross Unrealized Losses
Less Than Twelve Months	1,895	4,369
Over Twelve Months	3,921	496
Total	5,816	4,865
Fair Value
Less Than Twelve Months	189,486	197,914
Over Twelve Months	117,156	10,120
Total	306,642	208,034
US Government agency
Gross Unrealized Losses
Less Than Twelve Months	559	472
Over Twelve Months	615	141
Total	1,174	613
Fair Value
Less Than Twelve Months	45,221	36,941
Over Twelve Months	30,155	4,263
Total	75,376	41,204
Private label
Gross Unrealized Losses
Less Than Twelve Months	0	0
Over Twelve Months	5	11
Total	5	11
Fair Value
Less Than Twelve Months	8	107
Over Twelve Months	130	312
Total	138	419
Obligations of states and political subdivisions thereof
Gross Unrealized Losses
Less Than Twelve Months	58	3,252
Over Twelve Months	671	155
Total	729	3,407
Fair Value
Less Than Twelve Months	8,298	76,803
Over Twelve Months	27,727	3,916
Total	36,025	80,719
Corporate bonds
Gross Unrealized Losses
Less Than Twelve Months	53	0
Over Twelve Months	0	0
Total	53	0
Fair Value
Less Than Twelve Months	8,943	0
Over Twelve Months	0	0
Total	$ 8,943	$ 0