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Contractual interest rate for funds borrowed, under the debt agreement.

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FINANCING ARRANGEMENTS (Summary of Financing Arrangements) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2012	Jul. 30, 2012
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 7,535	$ 4,000
Long-term obligations, at par	1,579,697	1,639,000
Unamortized debt issuance costs and premium, net	(14,676)	(13,463)
Long-term obligations, at carrying value	1,565,021	1,625,537
Secured Debt \| Term Loan Agreement
Debt Instrument [Line Items]
Current portion of long-term obligations	7,535	4,000
Long-term obligations, at par	734,697	394,000
Senior Notes \| Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 0	400,000
Interest rate (as a percent)	5.25%			5.25%
Senior Notes \| Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 845,000	$ 845,000
Interest rate (as a percent)	5.125%		5.125%