EQUIPMENT AND PROPERTY (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Net equipment and property	$ 134,088	$ 133,477
Depreciation expense	27,381	24,725	$ 19,354
Foreign countries
Property, Plant and Equipment [Line Items]
Net equipment and property	4,900	4,600
Buildings
Property, Plant and Equipment [Line Items]
Gross equipment and property	51,023	50,119
Operating equipment
Property, Plant and Equipment [Line Items]
Gross equipment and property	91,430	82,196
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Gross equipment and property	17,672	16,255
Computer equipment and systems
Property, Plant and Equipment [Line Items]
Gross equipment and property	163,220	150,661
Equipment and Property
Property, Plant and Equipment [Line Items]
Gross equipment and property	323,345	299,231
Less--Accumulated Depreciation	(213,809)	(190,279)
Net equipment and property	109,536	108,952
Land
Property, Plant and Equipment [Line Items]
Gross equipment and property	$ 24,552	$ 24,525