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DERIVATIVE FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Details) | 12 Months Ended
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Dec. 31, 2018 USD ($) MMcf | Dec. 31, 2017 USD ($) MMcf
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] |  |
Derivative, Nonmonetary Notional Amount | MMcf | 14,300 | 14,100
Premiums recorded in other current assets on natural gas contracts held | $ 4,100,000 | $ 5,500,000
Fair Value Assets, Transfers between Levels | 0 | 0
Long-term Debt | 1,300,000,000 | 1,200,000,000
Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] |  |
Fair value of natural gas call options held | 2,100,000 | 1,100,000
Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] |  |
Long-term Debt, Fair Value | $ 1,400,000,000 | $ 1,300,000,000

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Amount of transfers of assets measured on a recurring basis between levels of the fair value hierarchy. + References No definition available. + Details
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- Definition The fair value of natural gas call options held, which are recorded in other currents assets. + References No definition available. + Details
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- Definition The amount of premiums recorded in other current assets on natural gas contracts held + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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