ACCUMULATED OTHER COMPREHENSIVE LOSS, Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in Accumulated Other Comprehensive (Loss) Income by Component [Roll Forward]
Balance		$ 158,434	$ 233,122	$ 224,273
Other comprehensive income (loss) before reclassifications		11,427	(9,676)
Amounts reclassified from accumulated other comprehensive income (loss)		245	255
Net current period other comprehensive income (loss)		11,672	(9,421)	(9,928)
Balance		157,960	158,434	233,122
Accumulated Other Comprehensive Income (Loss) [Member]
Changes in Accumulated Other Comprehensive (Loss) Income by Component [Roll Forward]
Balance		(31,297)	(21,876)	(11,948)
Balance		(19,625)	(31,297)	(21,876)
Foreign Currency Translation Adjustment [Member]
Changes in Accumulated Other Comprehensive (Loss) Income by Component [Roll Forward]
Balance		(28,976)	(19,305)
Other comprehensive income (loss) before reclassifications		12,439	(9,671)
Amounts reclassified from accumulated other comprehensive income (loss)		0	0
Net current period other comprehensive income (loss)		12,439	(9,671)
Balance		(16,537)	(28,976)	(19,305)
Unrealized Holding Gains on Available-for-Sale Securities [Member]
Changes in Accumulated Other Comprehensive (Loss) Income by Component [Roll Forward]
Balance		424	434
Other comprehensive income (loss) before reclassifications		(279)	(10)
Amounts reclassified from accumulated other comprehensive income (loss)		0	0
Net current period other comprehensive income (loss)		(279)	(10)
Balance		145	424	434
Unfunded SERP Liability [Member]
Changes in Accumulated Other Comprehensive (Loss) Income by Component [Roll Forward]
Balance		(2,745)	(3,005)
Other comprehensive income (loss) before reclassifications		(733)	5
Amounts reclassified from accumulated other comprehensive income (loss)	[1]	245	255
Net current period other comprehensive income (loss)		(488)	260
Balance		$ (3,233)	$ (2,745)	$ (3,005)

[1] This reclassification relates to the amortization of prior service costs and gains/losses associated with the Company's SERP plan. This expense is allocated between cost of sales and selling, general and administrative expense based upon the employment classification of the plan participants.