NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Recently Adopted Accounting Pronouncements) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Cash Flows—Operating Activities	$ 448,324	$ 425,468	$ 364,934
Net Cash Flows—Investing Activities	(391,813)	(372,877)	(500,917)
Net Cash Flows—Financing Activities	(50,335)	(69,133)	119,471
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	6,176	(16,542)	(16,512)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	43,325	59,867	76,379
Cash, Cash Equivalents, and Restricted Cash, End of Period	37,701	35,962	56,000
New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Cash Flows—Operating Activities		425,000	365,000
Net Cash Flows—Investing Activities		(373,000)	(501,000)
Net Cash Flows—Financing Activities		(69,000)	120,000
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash		(17,000)	(16,000)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	43,000	60,000	76,000
As Filed \| New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Cash Flows—Operating Activities		425,000	365,000
Net Cash Flows—Investing Activities		(376,000)	(503,000)
Net Cash Flows—Financing Activities		(69,000)	120,000
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash		(20,000)	(18,000)
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	36,000	56,000	74,000
Adoption of ASU Impacts \| New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net Cash Flows—Operating Activities		0	0
Net Cash Flows—Investing Activities		3,000	2,000
Net Cash Flows—Financing Activities		0	0
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash		3,000	2,000
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	$ 7,000	$ 4,000	$ 2,000

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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Amount of cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage. Excludes amount for disposal group and discontinued operations. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of increase (decrease) in cash and cash equivalents, and cash and cash equivalents restricted to withdrawal or usage; excluding effect from exchange rate change. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of cash inflow (outflow) from financing activities, including discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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