SUPPLEMENTAL CASH FLOW INFORMATION (Supplemental Information Referable to Condensed Consolidated Statements of Cash Flows) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
SUPPLEMENTAL CASH FLOW INFORMATION [Abstract]
Interest (exclusive of amount capitalized)	$ 13,184	$ 17,033
Income taxes	204	340
Accrued liabilities for purchases of property, plant & equipment	24,832	25,862
Recognition of new asset retirement obligations	938	0
Right-of-use assets obtained in exchange for new: Operating lease liabilities	5,591	21,522
Right-of-use assets obtained in exchange for new: Finance lease liabilities	$ 2,842	$ 2,678

Future cash outflow to pay for purchases of fixed assets that have occurred.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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