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Summary of Significant Accounting Policies Earnings Per Share (Details) $ / shares in Units, shares in Thousands, $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 USD ($) $ / shares shares | Dec. 31, 2015 USD ($) $ / shares shares | Dec. 31, 2014 USD ($) $ / shares shares | Aug. 12, 2016 USD ($)
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] |  |  |  |  |  |  |
Capped Call, Cap Price | $ / shares |  | $ 60.00 |  |  |  |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |  | 280 |  | 256 |  | 0 |
Earnings Per Share Reconciliation [Abstract] |  |  |  |  |  |  |
Net Income (loss) | $ |  | $ (757,744) |  | $ (447,710) |  | $ 666,051 |
Weighted Average Number of Shares Outstanding, Basic |  | 76,568 |  | 67,723 |  | 67,230 |
Incremental Common Shares Attributable to Share-based Payment Arrangements | [1] | 0 |  | 0 |  | 814 |
Incremental Common Shares Attributable to Conversion of Debt Securities, Treasury Stock Method |  | 0 | [2] | 0 | [2] | 0 |
Weighted Average Number of Shares Outstanding, Diluted |  | 76,568 |  | 67,723 |  | 68,044 |
Basic net income (loss) per common share | $ / shares |  | $ (9.90) |  | $ (6.61) |  | $ 9.91 |
Diluted net income (loss) per common share | $ / shares |  | $ (9.90) |  | $ (6.61) |  | $ 9.79 |
Performance Shares [Member] |  |  |  |  |  |  |
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] |  |  |  |  |  |  |
Award Vesting Period |  | 3 years |  |  |  |  |
Multiplier Applied to PSU Awards at Settlement |  | 0.2 |  | 1.0 |  | 0.55 |
Minimum [Member] | Performance Shares [Member] |  |  |  |  |  |  |
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] |  |  |  |  |  |  |
Multiplier Applied to PSU Awards at Settlement |  | 0 |  |  |  |  |
Maximum [Member] | Performance Shares [Member] |  |  |  |  |  |  |
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] |  |  |  |  |  |  |
Multiplier Applied to PSU Awards at Settlement |  | 2 |  |  |  |  |
Convertible Debt [Member] | 1.50% Senior Convertible Notes Due 2021 [Domain] |  |  |  |  |  |  |
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount | $ |  | $ 172,500 |  | $ 0 |  |  | $ 172,500
Debt Instrument, Convertible, Conversion Price | $ / shares |  | $ 40.50 |  |  |  |  |
[1] | For the years ended December 31, 2016, and 2015, the shares were anti-dilutive and excluded from the calculation of diluted earnings per share.
[2] | For the year ended December 31, 2016, shares of the Company’s common stock traded at an average closing price below the $40.50 conversion price, and therefore, had no dilutive impact and were excluded from the calculation of diluted earnings per share.

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