Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands |
12 Months Ended | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
Aug. 18, 2014 |
Apr. 23, 2014 |
Dec. 21, 2012 |
Oct. 17, 2012 |
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| Debt Instrument [Line Items] | |||||||||
| Asset retirement obligation capitalized | $ 8,800 | $ 9,295 | $ 3,556 | ||||||
| Unamortized discount | 2,500 | ||||||||
| Debt Instrument, Unamortized Discount (Premium), Net | [1] | (12,493) | $ (14,658) | ||||||
| Fair value of notes | 846,900 | ||||||||
| December Notes | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Unamortized premium | 300 | ||||||||
| Debt Instrument, Unamortized Discount (Premium), Net | 1,100 | ||||||||
| August Notes | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Unamortized premium | 14,700 | ||||||||
| Debt Instrument, Unamortized Discount (Premium), Net | 4,900 | ||||||||
| October Notes | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Debt Instrument, Unamortized Discount (Premium), Net | 5,100 | ||||||||
| April Notes | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Debt Instrument, Unamortized Discount (Premium), Net | $ 6,800 | ||||||||
| Senior Notes | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Carrying value of debt | 944,600 | ||||||||
| Unamortized discount | $ 3,700 | ||||||||
| Unamortized premium | $ 18,000 | $ 500 | |||||||
| Level 3 | |||||||||
| Debt Instrument [Line Items] | |||||||||
| Asset retirement obligation capitalized | $ 8,800 | ||||||||
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- Definition Amount of asset retirement obligations incurred during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Represents the aggregate of total long-term debt, including current maturities and short-term debt. No definition available.
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