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Long-Term Debt - Summary of Long-Term Debt (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Debt Instrument [Line Items] |  |  |
Net unamortized debt issuance costs | $ (23,751) | $ (30,733) |
Less: current maturities of long term debt | (631) | (651) |
Debt reflected as long term | 1,978,020 | 2,086,765 |
Senior notes | 6.625% Senior Notes Due 2023 |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | 329,467 | $ 350,000 |
Net unamortized debt issuance costs | $ (3,300) |  |
Stated interest rate | 6.625% | 6.625% | 6.625%
Senior notes | 6.000% Senior Notes Due 2024 |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | $ 603,428 | $ 650,000 |
Net unamortized debt issuance costs | $ (6,900) |  |
Stated interest rate | 6.00% | 6.00% | 6.00%
Senior notes | 6.375% Senior Notes Due 2025 |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | $ 529,525 | $ 600,000 |
Net unamortized debt issuance costs | $ (9,600) |  |
Stated interest rate | 6.375% | 6.375% | 6.375%
Senior notes | 6.375% Senior Notes Due 2026 |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | $ 397,529 | $ 450,000 |
Net unamortized debt issuance costs | $ (3,900) |  |
Stated interest rate | 6.375% | 6.375% | 6.375%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Amended and Restated Credit Agreement |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | $ 120,000 | $ 45,000 |
InterBank | Letter of credit | Construction loans |  |  |
Debt Instrument [Line Items] |  |  |
Long-tern debt | 22,453 | $ 23,149 |
Net unamortized debt issuance costs | $ (100) |  |

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