Derivative Financial Instruments (Details 2) $ in Thousands	Sep. 30, 2018 USD ($) bbl $ / bbl	Dec. 31, 2017 USD ($)
Summary of gross liability balances of derivative instruments
Total	$ (24,732)	$ (15,239)
Gross amounts netted in the condensed consolidated balance sheets	0	0
Net amounts presented in the condensed consolidated balance sheets	(24,732)	(15,239)
Current assets
Derivative [Line Items]
Gross amounts of recognized assets	49,723	131,092
Gross amounts netted in the condensed consolidated balance sheets	(49,719)	(129,902)
Oil, natural gas and natural gas liquids (NGL) derivatives	4	1,190
Other assets
Derivative [Line Items]
Gross amounts of recognized assets	654
Gross amounts netted in the condensed consolidated balance sheets	(654)
Oil, natural gas and natural gas liquids (NGL) derivatives	0
Current liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	(69,459)	(146,331)
Gross amounts netted in the condensed consolidated balance sheet	49,719	129,902
Oil, natural gas and natural gas liquids (NGL) derivatives	(19,740)	$ (16,429)
Other liabilities
Summary of gross liability balances of derivative instruments
Gross amounts of recognized liabilities	(5,650)
Gross amounts netted in the condensed consolidated balance sheet	654
Oil, natural gas and natural gas liquids (NGL) derivatives	(4,996)
Open Costless Collar Contracts
Summary of gross liability balances of derivative instruments
Derivative Assets (Liabilities), at Fair Value, Net	$ (33,518)
Derivative Contract, Calculation Period One | Oil - WTI | Open Three-way Costless Collar Contracts
Derivative [Line Items]
Notional Quantity (Bbl or MMBtu) | bbl	480,000
Summary of gross liability balances of derivative instruments
Derivative, Floor Price | $ / bbl	50.08
Derivative Assets (Liabilities), at Fair Value, Net	$ (1,369)
Derivative Contract, Calculation Period One | Oil - WTI | Open Costless Collar Contracts
Derivative [Line Items]
Notional Quantity (Bbl or MMBtu) | bbl	720,000
Summary of gross liability balances of derivative instruments
Derivative, Floor Price | $ / bbl	44.27
Derivative, Cap Price | $ / bbl	60.29
Derivative Assets (Liabilities), at Fair Value, Net	$ (9,240)