SUPPLEMENTAL BALANCE SHEET AND CASH FLOW INFORMATION (property, plant and equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, plant and equipment [Line Items]
Gross carrying amount	$ 473,647	$ 457,547
Accumulated depreciation	(377,180)	(367,205)
Net carrying amount	96,467	90,342
Machinery and equipment [Member]
Property, plant and equipment [Line Items]
Gross carrying amount	327,151	313,000
Accumulated depreciation	(282,741)	(275,721)
Net carrying amount	44,410	37,279
Buildings and improvements [Member]
Property, plant and equipment [Line Items]
Gross carrying amount	118,284	116,348
Accumulated depreciation	(86,162)	(83,317)
Net carrying amount	32,122	33,031
Land and improvements [Member]
Property, plant and equipment [Line Items]
Gross carrying amount	28,212	28,199
Accumulated depreciation	(8,277)	(8,167)
Net carrying amount	$ 19,935	$ 20,032