Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	$ 29,455us-gaap_DerivativeAssets	$ 37,428us-gaap_DerivativeAssets
Gross Amounts Not Offset in the Consolidated Balance Sheet	(30)
Net Amount	29,425	37,428
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(187)us-gaap_DerivativeLiabilities
Gross Amounts Not Offset in the Consolidated Balance Sheet	30
Net Amount	(157)
Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	19,164	20,921
Gross Amounts Not Offset in the Consolidated Balance Sheet	(30)
Net Amount	19,134	20,921
Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	10,291	16,507
Net Amount	10,291	16,507
Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(187)
Gross Amounts Not Offset in the Consolidated Balance Sheet	30
Net Amount	(157)
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	29,455	37,428
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(187)
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments \| Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	19,164	20,921
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments \| Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	10,291	16,507
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments \| Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(187)
Commodity contracts \| Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	15,161	18,652
Gross Amounts Not Offset in the Consolidated Balance Sheet	(30)
Net Amount	15,131	18,652
Commodity contracts \| Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(187)
Gross Amounts Not Offset in the Consolidated Balance Sheet	30
Net Amount	(157)
Embedded derivatives in commodity contracts \| Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	4,003	2,269
Net Amount	4,003	2,269
Embedded derivatives in commodity contracts \| Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	10,291	16,507
Net Amount	$ 10,291	$ 16,507

Fair value, after effects of master netting arrangements, deduction of assets not subject to a master netting arrangement and elected not to be offset, of 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, offset against an obligation to return collateral.

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