ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassification out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net			$ 0	$ (12)
Other components of net periodic pension and postretirement benefits	$ (408)	$ (333)	(816)	(666)
Income tax expense	486	1,263	1,547	2,540
Net income	(2,527)	(2,956)	(6,966)	(5,935)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net income	14	12	27	33
Accumulated Net Investment Gain (Loss) Attributable to Parent | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net	0	(12)	0	(12)
Income tax expense	0	4	0	4
Net income	0	(8)	0	(8)
Defined Benefit and Other Benefit Plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	(4)	(13)	(9)	(25)
Net income	14	20	27	41
Prior Service Costs | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other components of net periodic pension and postretirement benefits	(55)	(55)	(110)	(110)
Actuarial Losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other components of net periodic pension and postretirement benefits	$ 73	$ 88	$ 146	$ 176