INCOME TAXES - Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
United States-Federal									$ 375	$ 15,763	$ (1,308)
United States-State									500	505	(383)
Foreign									11,289	10,528	7,959
Total current income tax expense									12,164	26,796	6,268
Deferred:
United States-Federal									(10,892)	(1,880)	16,760
United States-State									950	(291)	1,636
Foreign									(3,563)	(3,465)	(527)
Total deferred income tax expense (benefit)									(13,505)	(5,636)	17,869
Consolidated:
United States-Federal									(10,517)	13,883	15,452
United States-State									1,450	214	1,253
Foreign									7,726	7,063	7,432
Total Income Tax Expense	$ (6,181)	$ (884)	$ 2,596	$ 3,128	$ 3,982	$ 9,602	$ 2,945	$ 4,631	(1,341)	21,160	$ 24,137
Deferred tax assets:
Receivables reserve	1,524				1,470				1,524	1,470
Temporary differences not currently deductible for tax	7,869				8,918				7,869	8,918
Deferred compensation	1,446				2,461				1,446	2,461
Pension	245				1,085				245	1,085
Net operating losses	26,685				29,571				26,685	29,571
Tax Credits	8,969								8,969
Total deferred tax asset	46,738				43,505				46,738	43,505
Deferred tax liabilities:
Property, plant and equipment, net	35,630				41,136				35,630	41,136
Intangible assets, net	5,817				6,122				5,817	6,122
Total deferred tax liabilities	41,447				47,258				41,447	47,258
Valuation allowance	(35,829)				(42,462)				(35,829)	(42,462)
Net deferred tax liabilities	(30,538)				(46,215)				(30,538)	(46,215)
Deferred tax assets:
Long term and total deferred tax asset	1,194				407				1,194	407
Deferred tax liabilities:
Long term and total deferred tax liabilities	(31,732)				(46,622)				(31,732)	(46,622)
Net deferred tax liabilities	$ (30,538)				$ (46,215)				$ (30,538)	$ (46,215)