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Senior Unsecured Notes (Details) - USD ($) $ in Thousands | Sep. 30, 2021 | Jun. 23, 2021 | Dec. 31, 2020 | Sep. 30, 2020
--- | --- | --- | --- | ---
Senior Notes [Line Items] |  |  |  |
Unsecured Long-term Debt, Noncurrent | $ 1,672,623 |  | $ 1,660,663 |
6.125% Senior Unsecured Notes due 2022 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 6.125% |  | 6.125% |
Senior Notes, Principal amount | $ 0 |  | $ 212,403 |
Senior Notes, unamortized deferred financing costs | 0 |  | 855 |
Unsecured Long-term Debt, Noncurrent | $ 0 |  | $ 211,548 |
5.0% Senior Unsecured Notes due 2024 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 5.00% |  | 5.00% |
Senior Notes, Principal amount | $ 104,769 |  | $ 277,034 |
Senior Notes, unamortized deferred financing costs | 451 |  | 1,576 |
Unsecured Long-term Debt, Noncurrent | $ 104,318 |  | $ 275,458 |
5.625% Senior Unsecured Notes due 2025 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 5.625% |  | 5.625% |
Senior Notes, Principal amount | $ 349,118 |  | $ 349,118 |
Senior Notes, unamortized deferred financing costs | 2,318 |  | 2,792 |
Unsecured Long-term Debt, Noncurrent | $ 346,800 |  | $ 346,326 |
6.75% Senior Unsecured Notes due 2026 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 6.75% |  | 6.75% |
Senior Notes, Principal amount | $ 419,235 |  | $ 419,235 |
Senior Notes, unamortized deferred financing costs | 3,445 |  | 3,970 |
Unsecured Long-term Debt, Noncurrent | $ 415,790 |  | $ 415,265 |
6.625% Senior Unsecured Notes due 2027 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 6.625% |  | 6.625% |
Senior Notes, Principal amount | $ 416,791 |  | $ 416,791 |
Senior Notes, unamortized deferred financing costs | 4,143 |  | 4,725 |
Unsecured Long-term Debt, Noncurrent | $ 412,648 |  | $ 412,066 |
6.5% Senior Unsecured Notes Due 2028 |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage | 6.50% | 6.50% | 6.50% |
Senior Notes, Principal amount | $ 400,000 | $ 400,000 | $ 0 |
Senior Notes, unamortized deferred financing costs | 6,933 |  | 0 |
Unsecured Long-term Debt, Noncurrent | 393,067 |  | 0 |
Senior Unsecured Notes [Member] |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, Principal amount | 1,689,913 |  | 1,674,581 |
Senior Notes, unamortized deferred financing costs | $ 17,290 |  | $ 13,918 |
1.50% Senior Unsecured Convertible Notes Due 2021 [Member] |  |  |  |
Senior Notes [Line Items] |  |  |  |
Senior Notes, interest rate, stated percentage |  |  |  | 1.50%

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