Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Derivative [Line Items]
Oil, natural gas and NGL derivatives	$ 23,460	$ 55,549
Summary of gross liability balances of derivative instruments
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	0
Other Current Assets [Member]
Derivative [Line Items]
Gross amounts of recognized assets	27,731	56,255
Derivative Asset, Fair Value, Gross Liability	(3,885)	(706)
Oil, natural gas and NGL derivatives	23,846	55,549
Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	(3,885)	(706)
Gross amounts netted in the condensed consolidated balance sheet	(3,885)	(706)
Net amounts of liabilities presented in the condensed consolidated balance sheet	0	$ 0
Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	(3,258)
Gross amounts netted in the condensed consolidated balance sheet	(2,871)
Net amounts of liabilities presented in the condensed consolidated balance sheet	(387)
Other Noncurrent Assets [Member]
Derivative [Line Items]
Gross amounts of recognized assets	2,872
Derivative Asset, Fair Value, Gross Liability	(2,871)
Oil, natural gas and NGL derivatives	$ 1