COMMITMENTS AND CONTINGENCIES (NARRATIVE) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Initiation date of current line of credit agreement	Jun. 03, 2013
Line of Credit Facility, Expiration Date	Feb. 14, 2024
Initial Borrowing Capacity	$ 900,000
Maximum borrowing capacity	$ 1,200,000
Line of Credit Facility, Interest Rate Description	The maximum commitment under the Credit Facility is $900.0 million, with an accordion feature of up to $1.2 billion in the aggregate, if certain conditions are satisfied. The Credit Facility commitment fees are payable to the lenders in an amount equal to the unused portion of the Credit Facility multiplied by 0.150% per annum from the Credit Facility inception date until a compliance certificate is provided by the Company in connection with its quarterly financial statements for the quarter ended March 31, 2019, and thereafter as previously disclosed and as determined by reference to the Company's net leverage ratio. The Credit Agreement contains customary affirmative, negative, and financial covenants, which remained unchanged from the 2016 Credit Facility, except that the Company is now obligated to maintain a maximum net leverage ratio of 3.50 to 1.00, and a minimum Interest coverage Ratio of 2.50 to 1.00. The Credit Agreement permits accounts receivable factoring up to the greater of $75 million or 25% of the average book value of all accounts receivable over the most recent twelve month period.Base rate loans bear interest at a rate equal to the greatest of (i) Wells Fargo's prime rate, (ii) one half of 1% in excess of the federal funds effective rate, and (iii) 1.0% in excess of the one month Eurodollar rate; plus in each case a margin of 0% to 0.75% based on the Company's net leverage ratio. Eurodollar loans bear interest at London Interbank Offered Rate ("LIBOR") plus a margin of 1.0% to 1.75% based on the Company's net leverage ratio. Alternate currency loans bear interest at rates applicable to their respective currencies.
Line of Credit Facility, Collateral	Letter of credit fees are one eighth of 1% of the stated amount of the letter of credit on the date of issuance, renewal or amendment, plus an annual fee equal to the borrowing margin for Eurodollar loans.
Borrowings outstanding on credit facility	$ 242,000		$ 282,000
Average daily utilization under credit facility	335,900	$ 576,700
Remaining borrowing capacity under credit facility	465,000
Letters of credit issued under credit facility	3,100
Letters Of Credit Issued Outside Line Of Credit Facility	$ 600
Minimum
Ratio of Indebtedness to Net Capital	3.50
Maximum
Ratio of Indebtedness to Net Capital	1.00