COMMITMENTS AND CONTINGENCIES (NARRATIVE) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
INDEBTEDNESS [ABSTRACT]
Initial Borrowing Capacity	$ 900,000
Maximum borrowing capacity	$ 1,200,000
Line of Credit Facility, Interest Rate Description	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) 1.25% in excess of the one month London Interbank Offered Rate ("LIBOR"); plus in each case a margin of 0% to 0.75% based on the Company's net leverage ratio. Eurodollar loans bear interest at 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.
Description of line of credit agreement	The Credit Agreement provides for a secured revolving credit facility that matures on February 11, 2021 with an initial maximum aggregate commitment of $900 million, and an accordion feature of up to $1.2 billion in the aggregate, if certain conditions are satisfied.
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. The Credit Facility commitment fees are payable to the lenders in an amount equal to the unused portion of the Credit Facility at a rate of 0.125% to 0.250% based on the Company's net leverage ratio.The Company is obligated to maintain a maximum net leverage ratio no greater than 3.25 to 1.00, and a minimum interest coverage ratio no less than 2.50 to 1.00.
Borrowings outstanding on credit facility	$ 272,500		$ 344,000
Average daily utilization under credit facility	563,500	$ 474,300
Letters of credit issued under credit facility	3,800
Remaining borrowing capacity under credit facility	405,000
Letters Of Credit Issued Outside Line Of Credit Facility	$ 600