Commitments - Schedule of Firm Sales Contracted with Third Parties (Details) MMBTU / d in Thousands  | 
 Dec. 31, 2016  
MMBTU / d 
 | 
|---|---|
| Commitments and Contingencies Disclosure [Abstract] | |
| 2017 | 516 | 
| 2018 | 257 | 
| 2019 | 226 | 
| 2020 | 223 | 
| 2021 | 126 | 
| Thereafter | 31 | 
| Total | 1,379 | 
| X | ||||||||||
- Definition Supply Commitment, Due After Fifth Year No definition available. 
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| X | ||||||||||
- Definition Supply Commitment, Due in Next Twelve Months No definition available. 
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| X | ||||||||||
- Definition Supply Commitment, Due in Year Five No definition available. 
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| X | ||||||||||
- Definition Supply Commitment, Due in Year Four No definition available. 
  | 
| X | ||||||||||
- Definition Supply Commitment, Due in Year Three No definition available. 
  | 
| X | ||||||||||
- Definition Supply Commitment, Due in Year Two No definition available. 
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| X | ||||||||||
- Definition Supply Commitment, Total No definition available. 
  | 
| X | ||||||||||
- References No definition available. 
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