Derivative Financial Instruments (Details 3) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Derivative instruments, Balance Sheet Location
Derivatives assets - current	$ 163,869,000us-gaap_DerivativeAssetsCurrent	$ 163,275,000us-gaap_DerivativeAssetsCurrent
Derivatives assets-long-term	77,475,000us-gaap_DerivativeAssetsNoncurrent	89,210,000us-gaap_DerivativeAssetsNoncurrent
Derivatives liabilities - current	(973,000)us-gaap_DerivativeLiabilitiesCurrent	(721,000)us-gaap_DerivativeLiabilitiesCurrent
Derivatives liabilities - long-term	(7,821,000)us-gaap_DerivativeLiabilitiesNoncurrent	(68,000)us-gaap_DerivativeLiabilitiesNoncurrent
Not designated as hedging instruments
Derivative instruments, Balance Sheet Location
Total	232,550,000	251,696,000
Commodity derivatives \| Not designated as hedging instruments
Derivative instruments, Balance Sheet Location
Derivatives assets - current	163,869,000	163,275,000
Derivatives assets-long-term	77,375,000	89,210,000
Derivatives liabilities - long-term	(7,731,000)
Net deferred premiums payable related to commodity derivative contracts	2,600,000	1,800,000
Net deferred premiums payable related to commodity derivative contracts	5,600,000	6,900,000
Interest rate contracts \| Not designated as hedging instruments
Derivative instruments, Balance Sheet Location
Derivatives assets-long-term	100,000
Derivatives liabilities - current	(973,000)	(721,000)
Derivatives liabilities - long-term	$ (90,000)	$ (68,000)

Represents the amount of deferred premiums of the derivative contracts included in current derivative assets.

No definition available.

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- Definition

Represents the amount of deferred premiums of the derivative contracts included in noncurrent derivative assets.

+ References

No definition available.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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-Glossary Current Assets

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- Definition

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

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-Publisher FASB

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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