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LONG-TERM DEBT (Break-Down of Long-Term Debt) (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Instrument [Line Items] |  |
Net unamortized debt issuance costs | $ (29,628) | $ (30,733)
Less: current maturities of long term debt | (656) | (651)
Long-term debt, net of current maturities | 2,087,714 | 2,086,765
Construction loan |  |
Debt Instrument [Line Items] |  |
Net unamortized debt issuance costs | (100) |
6.625% senior unsecured notes due 2023 | Senior notes |  |
Debt Instrument [Line Items] |  |
Long-term debt | 350,000 | 350,000
Net unamortized debt issuance costs | $ (4,200) |
Stated interest rate, percent | 6.625% |
6.000% senior unsecured notes due 2024 | Senior notes |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 650,000 | 650,000
Net unamortized debt issuance costs | $ (8,400) |
Stated interest rate, percent | 6.00% |
6.375% senior unsecured notes due 2025 | Senior notes |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 600,000 | 600,000
Net unamortized debt issuance costs | $ (12,100) |
Stated interest rate, percent | 6.375% |
6.375% senior unsecured notes due 2026 | Senior notes |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 450,000 | 450,000
Net unamortized debt issuance costs | $ (4,900) |
Stated interest rate, percent | 6.375% |
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Revolving credit agreement |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 45,000 | 45,000
InterBank | Letter of credit | Construction loan |  |
Debt Instrument [Line Items] |  |
Long-term debt | $ 22,998 | $ 23,149

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