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Long-Term Debt - Summary of Long-Term Debt (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Oct. 11, 2017 | Dec. 31, 2016 | Dec. 21, 2016 | Oct. 14, 2016 | Apr. 21, 2015 | Mar. 31, 2011
--- | --- | --- | --- | --- | --- | --- | ---
Debt Instrument [Line Items] |  |  |  |  |  |  |
Net unamortized original issue premium (discount) | $ 0 |  | $ 0 |  |  |  |
Net unamortized debt issuance costs | (34,781) |  | (27,174) |  |  |  |
Less: current maturities of long term debt | (622) |  | (276) |  |  |  |
Debt reflected as long term | 2,038,321 |  | 1,593,599 |  |  |  |
Revolving credit agreement |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | 0 |  | 0 |  |  |  |
Building loans |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | 0 |  | 0 |  |  |  |
Stated interest rate |  |  |  |  |  |  | 4.00%
Senior notes | 7.75% Senior Notes Due 2020 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 0 |  | $ 0 |  |  |  |
Stated interest rate | 7.75% |  | 7.75% |  |  |  |
Senior notes | 6.625% Senior Notes Due 2023 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 350,000 |  | $ 350,000 |  |  |  |
Net unamortized debt issuance costs | $ (5,200) |  |  |  |  |  |
Stated interest rate | 6.625% |  | 6.625% |  |  | 6.625% |
Senior notes | 6.000% Senior Notes Due 2024 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 650,000 |  | $ 650,000 |  |  |  |
Net unamortized debt issuance costs | $ (9,900) |  |  |  |  |  |
Stated interest rate | 6.00% |  | 6.00% |  | 6.00% |  |
Senior notes | 6.375% Senior Notes Due 2025 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 600,000 |  | $ 600,000 |  |  |  |
Net unamortized debt issuance costs | $ (14,000) |  |  |  |  |  |
Stated interest rate | 6.375% |  | 6.375% | 6.375% |  |  |
Senior notes | 6.375% Senior Notes Due 2026 |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 450,000 |  | $ 0 |  |  |  |
Net unamortized debt issuance costs | $ (5,500) |  |  |  |  |  |
Stated interest rate | 6.375% | 6.375% |  |  |  |  |
Construction loans |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |
Long-tern debt | $ 23,724 |  | $ 21,049 |  |  |  |

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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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 + Details
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