ACCUMULATED OTHER COMPREHENSIVE INCOME - Changes in accumulated other comprehensive income by component, net of tax (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 204,912	$ 205,452	$ 205,600	$ 207,432	$ 223,356	$ 237,621	$ 205,600	$ 237,621
Other comprehensive income (loss) before reclassification	(844)	172	317	61	958	(2,961)
Amounts reclassified from accumulated other comprehensive income	303	291	280	263	(138)	30
Total other comprehensive (loss) income	(541)	463	597	324	820	(2,931)	519	(1,787)
Balance at end of period	448,235	204,912	205,452	206,091	207,432	223,356	448,235	206,091
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	29	(434)	(1,031)	(2,628)	(3,448)	(517)	(1,031)	(517)
Total other comprehensive (loss) income	(541)	463	597		820	(2,931)
Balance at end of period	(512)	29	(434)	(2,304)	(2,628)	(3,448)	(512)	(2,304)
Gains and Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1,567)	(672)	(3,986)	(5,066)	(4,392)	(360)	(3,986)	(360)
Other comprehensive income (loss) before reclassification	209	(1,149)	3,071	68	(743)	(4,031)
Amounts reclassified from accumulated other comprehensive income	265	254	243	228	69	(1)
Total other comprehensive (loss) income	474	(895)	3,314	296	(674)	(4,032)
Balance at end of period	(1,093)	(1,567)	(672)	(4,770)	(5,066)	(4,392)	(1,093)	(4,770)
Unrealized gains on securities available for sale: Realized (losses) gains on securities available for sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	2,775	1,454	4,208	3,687	1,986	916	4,208	916
Other comprehensive income (loss) before reclassification	(1,053)	1,321	(2,754)	(7)	1,701	1,070
Amounts reclassified from accumulated other comprehensive income	0	0	0	0	0	0
Total other comprehensive (loss) income	(1,053)	1,321	(2,754)	(7)	1,701	1,070
Balance at end of period	1,722	2,775	1,454	3,680	3,687	1,986	1,722	3,680
Defined Benefit Pension Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1,179)	(1,216)	(1,253)	(1,249)	(1,042)	(1,073)	(1,253)	(1,073)
Other comprehensive income (loss) before reclassification	0	0	0	0	0	0
Amounts reclassified from accumulated other comprehensive income	38	37	37	35	(207)	31
Total other comprehensive (loss) income	38	37	37	35	(207)	31
Balance at end of period	$ (1,141)	$ (1,179)	$ (1,216)	$ (1,214)	$ (1,249)	$ (1,042)	$ (1,141)	$ (1,214)