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Earnings Per Share (Details) $ / shares in Units, shares in Thousands, $ in Thousands |  | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2019 USD ($) $ / shares | Dec. 31, 2019 USD ($) $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2017 USD ($) $ / shares shares | Aug. 12, 2016 USD ($) $ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Capped Call, Cap Price | $ / shares |  |  |  |  | $ 60.00
Anti-dilutive shares excluded from earnings per share | shares |  | 684 | 0 | 264 |
Earnings Per Share Reconciliation [Abstract] |  |  |  |  |
Net income (loss) | $ |  | $ (187,001) | $ 508,407 | $ (160,843) |
Basic weighted-average common shares outstanding | shares |  | 112,544 | 111,912 | 111,428 |
Dilutive effect of non-vested RSUs and contingent PSUs | shares |  | 0 | 1,590 | 0 |
Diluted weighted-average common shares outstanding | shares |  | 112,544 | 113,502 | 111,428 |
Basic net income (loss) per common share | $ / shares |  | $ (1.66) | $ 4.54 | $ (1.44) |
Diluted net income (loss) per common share | $ / shares |  | $ (1.66) | $ 4.48 | $ (1.44) |
1.50% Senior Convertible Notes Due 2021 [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Senior Convertible Notes, principal amount | $ | $ 172,500 | $ 172,500 | $ 172,500 |  | $ 172,500
Senior Convertible Notes, conversion price | $ / shares | $ 40.50 | $ 40.50 |  |  |
Performance Shares [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Award vesting period | 3 years |  |  |  |
Multiplier applied to PSU awards at settlement | 0 | 0 | 0 | 0 |
Minimum [Member] | Performance Shares [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Multiplier applied to PSU awards at settlement | 0 | 0 |  |  |
Maximum [Member] | Performance Shares [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Multiplier applied to PSU awards at settlement | 2 | 2 |  |  |

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