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Derivative Instruments and Hedging Activities (Derivative Positions and Subsequent Event) (Details) (Commodity Contract [Member])
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Dec. 31, 2013
Natural gas [Member]
Average Ceiling Price per Instrument of $4.75 [Member]
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Mar. 31, 2013
Derivative Collar [Member]
Not Designated as Hedging Instrument [Member]
Crude Oil [Member]
Swap [Member]
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Dec. 31, 2013
Average Ceiling Price per Instrument of $4.75 [Member]
Not Designated as Hedging Instrument [Member]
Natural gas [Member]
Call Option [Member]
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Dec. 31, 2013
Fixed-Price Swap per Instrument of $4.36 [Member]
Not Designated as Hedging Instrument [Member]
Natural gas [Member]
Swap [Member]
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Dec. 31, 2013
Average Ceiling Price per Instrument of $4.75 A [Member]
Not Designated as Hedging Instrument [Member]
Natural gas [Member]
Call Option [Member]
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Dec. 31, 2013
Fixed-Price Swap per Instrument of $93.35 [Member]
Not Designated as Hedging Instrument [Member]
Crude Oil [Member]
Swap [Member]
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Dec. 31, 2013
Average Floor Price per Instrument of $70.00 [Member]
Not Designated as Hedging Instrument [Member]
Crude Oil [Member]
Put Option [Member]
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Mar. 31, 2013
Average Floor Price per Instrument of $70.00 [Member]
Not Designated as Hedging Instrument [Member]
Crude Oil [Member]
Put Option [Member]
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Dec. 31, 2013
Fixed-Price Swap per Instrument of $94.58 [Member]
Not Designated as Hedging Instrument [Member]
Crude Oil [Member]
Swap [Member]
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Dec. 31, 2013
Fixed-Price Swap per Instrument of $4.25 [Member]
Not Designated as Hedging Instrument [Member]
Natural gas [Member]
Swap [Member]
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Dec. 31, 2013
Average Ceiling Price per Instrument of $5.00 [Member]
Not Designated as Hedging Instrument [Member]
Natural gas [Member]
Call Option [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $94.15 [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $94.15 [Member]
Not Designated as Hedging Instrument [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $92.80 [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $92.80 [Member]
Not Designated as Hedging Instrument [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $90.40 [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $90.40 [Member]
Not Designated as Hedging Instrument [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $88.64 [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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Mar. 12, 2014
Fixed-Price Swap per Instrument of $88.64 [Member]
Not Designated as Hedging Instrument [Member]
Subsequent Event [Member]
Crude Oil [Member]
Swap [Member]
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Derivative [Line Items] | |||||||||||||||||||
| Derivative, Nonmonetary Notional Amount (in Volumes per Month) | 40,000 | 38,000 | 60,000 | 38,000 | 30,000 | 30,000 | 30,000 | 9,000 | 46,000 | 37,000 | 15,000 | 15,000 | 15,000 | 15,000 | |||||
| Derivative, Average Cap Price | 4.36 | 93.35 | 94.58 | 4.25 | 94.15 | 92.80 | 90.40 | 88.64 | |||||||||||
| Average Ceiling Price per Hedge (in dollars per instrument) | 4.75 | 4.75 | 4.75 | 70.00 | 5.00 |