INCOME TAXES - Effective Income Tax Reconciliation (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amount
Statutory Tax Rate									$ 14,918,000	$ 7,283,000	$ 7,392,000
State taxes, net of federal benefit									986,000	141,000	142,000
Tax exempt interest									(2,074,000)	(1,388,000)	(1,303,000)
Federal tax credits									(130,000)	0	0
Officers' life insurance									(538,000)	(244,000)	(209,000)
Acquisition Costs									89,000	289,000	0
Stock-based compensation plans									(241,000)	0	0
Impact of federal tax reform enactment									3,988,000	0	0
Other									(368,000)	(205,000)	(55,000)
Income Tax Expense (Benefit)	$ 8,545,000	$ 3,575,000	$ 3,029,000	$ 1,481,000	$ 426,000	$ 1,850,000	$ 1,804,000	$ 1,796,000	$ 16,630,000	$ 5,876,000	$ 5,967,000
Rate
Statutory Tax Rate									35.00%	35.00%	35.00%
State taxes, net of federal benefit									2.31%	0.68%	0.67%
Tax exempt interest									(4.87%)	(6.67%)	(6.17%)
Federal tax credits									(0.30%)	0.00%	0.00%
Officers' life insurance									(1.26%)	(1.17%)	(0.99%)
Acquisition Costs									0.21%	1.39%	0.00%
Stock-based compensation plans									(0.57%)	0.00%	0.00%
Impact of federal tax reform enactment									9.36%	0.00%	0.00%
Other									(0.86%)	(0.99%)	(0.26%)
Effective Tax Rate									39.02%	28.24%	28.25%