VALUATION AND QUALIFYING ACCOUNTS (Valuation and Qualifying Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Trade Receivables
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 2,014	$ 1,729	$ 2,181
Additions	998	3,500	1,704
Deductions/ Write offs	(1,826)	(3,215)	(2,156)
Balance at End of Year	1,186	2,014	$ 1,729
Valuation Allowance on Deferred Tax Assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	0
Additions	924
Deductions/ Write offs	0
Balance at End of Year	$ 924	$ 0