ACCUMULATED OTHER COMPREHENSIVE INCOME OR LOSS (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Beginning Balances		$ 149,813	$ 143,748	$ 137,242
Cumulative effect of accounting change	[1]				$ (162)
Balances as adjusted					149,651
Total other comprehensive income (loss)		(869)	2,251	188
Ending Balances		165,029	149,813	143,748
Net gains on securities transactions		0	109	987
Income tax expense		4,009	7,262	4,404
Pension and other employee benefits		5,524	5,510	4,850
Net of tax		19,626	7,430	10,027
Reclassification out of Accumulated Other Comprehensive Income (loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Net of tax		690	51	799
Unrealized Gains and Losses on Securities Available for Sale
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Beginning Balances		(3,415)	(4,356)	210
Cumulative effect of accounting change			(202)
Balances as adjusted					(3,617)
Other comprehensive income before reclassification		(1,029)	1,578	(3,952)
Amounts reclassified from accumulated other comprehensive income (loss)		0	(68)	(614)
Total other comprehensive income (loss)		(1,029)	1,510	(4,566)
Stranded AOCI reclassification			(569)
Ending Balances		(4,646)	(3,415)	(4,356)
Unrealized Gains and Losses on Securities Available for Sale | Reclassification out of Accumulated Other Comprehensive Income (loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Net gains on securities transactions		0	(109)	(987)
Income tax expense		0	41	373
Net of tax		0	(68)	(614)
Defined Benefit and Other Benefit Plans
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Beginning Balances		(6,925)	(6,398)	(11,152)
Cumulative effect of accounting change			0
Balances as adjusted					(6,925)
Other comprehensive income before reclassification		(530)	622	3,341
Amounts reclassified from accumulated other comprehensive income (loss)		690	119	1,413
Total other comprehensive income (loss)		160	741	4,754
Stranded AOCI reclassification			(1,268)
Ending Balances		(6,765)	(6,925)	(6,398)
Defined Benefit and Other Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income (loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Income tax expense		(236)	(74)	(856)
Net of tax		690	119	1,413
Net Prior Service Cost (Credit) | Reclassification out of Accumulated Other Comprehensive Income (loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Pension and other employee benefits		(220)	(220)	674
Net Unamortized Gain (Loss) | Reclassification out of Accumulated Other Comprehensive Income (loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Pension and other employee benefits		1,146	413	1,595
Accumulated Other Comprehensive Income (Loss)
Summary of changes in accumulated other comprehensive income or loss by component, net of tax [Roll Forward]
Beginning Balances		(10,340)	(10,754)	(10,942)
Cumulative effect of accounting change			(202)		(202)	[1]
Balances as adjusted					$ (10,542)
Other comprehensive income before reclassification		(1,559)	2,200	(611)
Amounts reclassified from accumulated other comprehensive income (loss)		690	51	799
Total other comprehensive income (loss)		(869)	2,251	188
Stranded AOCI reclassification			(1,837)
Ending Balances		$ (11,411)	$ (10,340)	$ (10,754)

[1] (b) Due to implementation of ASC 2016-01. See "Adoption of New Accounting Standards" discussion in Note 1.