ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Summary of components of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		$ (16,702)	$ (18,102)
Change during the period:
Before-tax amount		(496)	18
Tax benefit		0	9
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	173	135
Total activity for the period		(323)	162
Balance		(17,025)	(17,940)
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
Tax benefit		0	0
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	173	135
Total activity for the period		173	135
Balance		(14,297)	(15,368)
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)	(24)
Tax benefit		0	9
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	0	0
Total activity for the period		(15)	(15)
Balance		0	24
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(2,247)	(2,638)
Change during the period:
Before-tax amount		(481)	42
Tax benefit		0	0
Reclassification adjustment, net of taxes:
Amortization of net loss	[1]	0	0
Total activity for the period		(481)	42
Balance		$ (2,728)	$ (2,596)

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