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Derivative Instruments and Hedging Activities (Gain or loss on derivative contracts) (Details) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
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Jun. 30, 2014
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Jun. 30, 2013
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Jun. 30, 2014
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Jun. 30, 2013
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| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Net gain (loss) on fair value adjustments | $ (4,677) | $ 249 | ||
| Total gain (loss) on derivative instruments | (4,685) | 1,981 | (7,198) | 1,563 |
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Natural Gas [Member] | Not Designated as Hedging Instrument [Member]
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| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Net gain (loss) on settlements | (77) | (156) | (179) | (107) |
| Net gain (loss) on fair value adjustments | 58 | 485 | (132) | 97 |
| Total gain (loss) on derivative instruments | (19) | 329 | (311) | (10) |
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Crude Oil [Member] | Not Designated as Hedging Instrument [Member]
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| Derivative Instruments, Gain (Loss) [Line Items] | ||||
| Net gain (loss) on settlements | (1,569) | 849 | (2,341) | 1,422 |
| Net gain (loss) on fair value adjustments | (3,097) | 803 | (4,546) | 151 |
| Total gain (loss) on derivative instruments | $ (4,666) | $ 1,652 | $ (6,887) | $ 1,573 |