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Long-Term Debt Senior Notes (Details) - USD ($) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2016 | Mar. 31, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 | Dec. 31, 2015
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | $ 2,303,736,000 |  |  | $ 2,303,736,000 |  | $ 2,350,000,000
Unamortized Debt Issuance Expense | 31,156,000 |  |  | 31,156,000 |  | 34,030,000
Senior Notes, Noncurrent | 2,272,580,000 |  |  | 2,272,580,000 |  | 2,315,970,000
Gain (Loss) on Extinguishment of Debt | 0 |  | $ (16,578,000) | 15,722,000 | $ (16,578,000) |
6.50% Senior Notes Due 2021 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | 346,955,000 |  |  | 346,955,000 |  | 350,000,000
Unamortized Debt Issuance Expense | 3,721,000 |  |  | 3,721,000 |  | 4,106,000
Senior Notes, Noncurrent | 343,234,000 |  |  | 343,234,000 |  | 345,894,000
6.125% Senior Notes Due 2022 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | 561,796,000 |  |  | 561,796,000 |  | 600,000,000
Unamortized Debt Issuance Expense | 7,569,000 |  |  | 7,569,000 |  | 8,714,000
Senior Notes, Noncurrent | 554,227,000 |  |  | 554,227,000 |  | 591,286,000
6.50% Senior Notes Due 2023 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | 394,985,000 |  |  | 394,985,000 |  | 400,000,000
Unamortized Debt Issuance Expense | 4,801,000 |  |  | 4,801,000 |  | 5,231,000
Senior Notes, Noncurrent | 390,184,000 |  |  | 390,184,000 |  | 394,769,000
5% Senior Notes Due 2024 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | 500,000,000 |  |  | 500,000,000 |  | 500,000,000
Unamortized Debt Issuance Expense | 6,994,000 |  |  | 6,994,000 |  | 7,455,000
Senior Notes, Noncurrent | 493,006,000 |  |  | 493,006,000 |  | 492,545,000
5.625% Senior Notes Due 2025 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Face Amount | 500,000,000 |  |  | 500,000,000 |  | 500,000,000
Unamortized Debt Issuance Expense | 8,071,000 |  |  | 8,071,000 |  | 8,524,000
Senior Notes, Noncurrent | 491,929,000 |  |  | 491,929,000 |  | $ 491,476,000
Senior Notes [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Covenant Compliance, Dividends Excluded From Computation |  |  |  | 6,500,000 |  |
Debt Instrument, Repurchased Face Amount |  | $ 46,300,000 |  |  |  |
Debt Instrument, Repurchased Settlement Amount |  | $ 29,900,000 |  |  |  |
Early Repayment of Senior Debt, Accrued | $ 10,000,000 |  |  | 10,000,000 |  |
Gain (Loss) on Extinguishment of Debt |  |  |  | 15,722,000 |  |
Debt Instrument, Repurchase Discount |  |  |  | 16,400,000 |  |
Amortization of Debt Issuance Costs Related to Repurchase of Debt Instrument |  |  |  | $ 700,000 |  |
Senior Notes [Member] | 6.50% Senior Notes Due 2021 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% |  |  | 6.50% |  |
Senior Notes [Member] | 6.125% Senior Notes Due 2022 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.125% |  |  | 6.125% |  |
Senior Notes [Member] | 6.50% Senior Notes Due 2023 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 6.50% |  |  | 6.50% |  |
Senior Notes [Member] | 5% Senior Notes Due 2024 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.00% |  |  | 5.00% |  |
Senior Notes [Member] | 5.625% Senior Notes Due 2025 [Member] |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.625% |  |  | 5.625% |  |

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