PROPERTY PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	$ 266,184	$ 282,541
Less: Accumulated depreciation	(172,569)	(182,074)
Total property, plant, and equipment, net	93,615	100,467		$ 93,346	$ 93,381	$ 96,540	$ 102,485	$ 105,286	$ 109,124
Depreciation expense	29,700	31,000	$ 32,500
Annual future minimum lease payments under capital leases
Due in twelve months	343	467
Due in two years	198	268
Due in three years	121	121
Due in four years	50	39
Total	712	895
Land
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	644	704
Buildings
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	28,180	28,160
Assets under capital leases
Assets under capital leases	24,100	23,800
Accumulated depreciation of assets under capital leases	8,900	7,700
Furniture and fixtures
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	12,968	12,312
Machinery and equipment
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	26,838	26,173
Equipment leased to third parties under operating leases
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	31,100	32,669
Less: Accumulated depreciation	(19,954)	(22,850)
Total property, plant, and equipment, net	11,146	9,819
Leasehold improvements
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	100,999	95,376
Computers and software
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	$ 65,455	$ 87,147