Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	$ 23,127	$ 37,428
Gross Amounts Not Offset in the Consolidated Balance Sheet	(1,026)
Net Amount	22,101	37,428
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(1,219)
Gross Amounts Not Offset in the Consolidated Balance Sheet	1,026
Net Amount	(193)
Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	15,151	20,921
Gross Amounts Not Offset in the Consolidated Balance Sheet	(1,026)
Net Amount	14,125	20,921
Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	7,976	16,507
Net Amount	7,976	16,507
Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(1,164)
Gross Amounts Not Offset in the Consolidated Balance Sheet	1,026
Net Amount	(138)
Non-current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(55)
Net Amount	(55)
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	23,127	37,428
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(1,219)
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	15,151	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	7,976	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	(1,164)
Commodity contracts, including embedded derivatives \| Derivative instruments not designated as hedging instruments \| Non-current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(55)
Commodity contracts \| Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	11,241	18,652
Gross Amounts Not Offset in the Consolidated Balance Sheet	(1,026)
Net Amount	10,215	18,652
Commodity contracts \| Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	59
Net Amount	59
Commodity contracts \| Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(1,073)
Gross Amounts Not Offset in the Consolidated Balance Sheet	1,026
Net Amount	(47)
Commodity contracts \| Non-current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(55)
Net Amount	(55)
Embedded derivatives in commodity contracts \| Current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	3,910	2,269
Net Amount	3,910	2,269
Embedded derivatives in commodity contracts \| Non-current Assets
Assets
Total carrying value of derivative assets in Condensed Consolidated Balance Sheets	7,917	16,507
Net Amount	7,917	$ 16,507
Embedded derivatives in commodity contracts \| Current Liabilities
Liabilities
Total carrying value of derivative liabilities in Condensed Consolidated Balance Sheets	(91)
Net Amount	$ (91)

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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Fair value 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, elected not to be offset, deducted from derivative assets.

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