Risk Management and Derivative Instruments (Details 2) - Not designated as Hedging Instrument - Commodity Derivatives - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Risk Management and Derivative Instruments
Derivative financial instruments - Current Liabilities	$ (2,869)
Total derivative fair value at period end	33,991	$ 126,709
Derivative assets:
Gross Recognized Assets	36,860	126,709
Gross Amounts Offset, Assets	1,002
Net Recognized Fair Value Assets	35,858	126,709
Derivative liabilities:
Gross Recognized Liabilities	2,869
Gross Amounts Offset, Liabilities	1,002
Net Recognized Fair Value Liabilities	1,867
Current Assets
Derivative assets:
Gross Recognized Assets	36,860	126,709
Gross Amounts Offset, Assets	1,002
Net Recognized Fair Value Assets	35,858	126,709
Current Liabilities
Risk Management and Derivative Instruments
Derivative financial instruments - Current Liabilities	(2,869)
Derivative liabilities:
Gross Recognized Liabilities	2,869
Gross Amounts Offset, Liabilities	1,002
Net Recognized Fair Value Liabilities	1,867
Swaps | Current Assets | Oil
Derivative assets:
Gross Recognized Assets	27,708	106,450
Swaps | Current Assets | Gas
Derivative assets:
Gross Recognized Assets	9,152	$ 20,259
Swaps | Current Liabilities | Oil
Risk Management and Derivative Instruments
Derivative financial instruments - Current Liabilities	(2,869)
Derivative liabilities:
Gross Recognized Liabilities	$ 2,869