ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Summary of components of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		$ (16,702)	$ (18,102)
Change during the period:
Before-tax amount		(430)	198
Tax benefit			12
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	328	270
Total activity for the period		(102)	480
Balance		(16,804)	(17,622)
Pension Adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(14,470)	(15,503)
Change during the period:
Before-tax amount		0	0
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	328	270
Total activity for the period		328	270
Balance		(14,142)	(15,233)
Unrealized Gain (Loss) On Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		15	39
Change during the period:
Before-tax amount		(15)	(33)
Tax benefit			12
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	0	0
Total activity for the period		(15)	(21)
Balance		0	18
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(2,247)	(2,638)
Change during the period:
Before-tax amount		(415)	231
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	0	0
Total activity for the period		(415)	231
Balance		$ (2,662)	$ (2,407)

[1] Reported as part of selling, general and administrative expenses.