Derivative Financial Instruments - Cash Payments on Derivative Settlements, Net Included within Net Cash Provided by Operating Activities (Details) - USD ($) $ in Thousands  | 
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015  | 
Dec. 31, 2014  | 
Dec. 31, 2013  | 
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| Derivative Instruments And Hedging Activities Disclosure [Abstract] | |||
| Cash receipts (payments) on derivative settlements, net | $ 6,703 | $ (5,318) | $ (8,589) | 
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- References No definition available. 
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- Definition Net cash payments or net cash received related to derivative settlements. No definition available. 
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