Fair Value Measurements - Level 3 Measurements of Derivative Commodity Instruments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / bbl $ / gal	Dec. 31, 2017 USD ($)
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Derivative asset	$ 8,245	$ 0
Derivative liabilities	(69,041)	$ (80,265)
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2018
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Derivative asset	$ 22,319
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2018 | Minimum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per barrel (in dollars per Bbl) | $ / bbl	(4.41)
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2018 | Maximum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per barrel (in dollars per Bbl) | $ / bbl	(3.94)
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2019
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Derivative asset	$ 13,338
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2019 | Minimum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per barrel (in dollars per Bbl) | $ / bbl	(3.05)
Discounted Cash Flow Valuation Technique | Level 3 | Oil Basis - WTI/WTI | 2019 | Maximum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per barrel (in dollars per Bbl) | $ / bbl	(2.96)
Discounted Cash Flow Valuation Technique | Level 3 | Natural Gas Liquids | 2018
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Derivative liabilities	$ (10,489)
Price per gallon (in dollars per gal) | $ / gal	0.70
Discounted Cash Flow Valuation Technique | Level 3 | Natural Gas Liquids | 2019
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Derivative liabilities	$ (666)
Discounted Cash Flow Valuation Technique | Level 3 | Natural Gas Liquids | 2019 | Minimum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per gallon (in dollars per gal) | $ / gal	0.64
Discounted Cash Flow Valuation Technique | Level 3 | Natural Gas Liquids | 2019 | Maximum
Fair Value Inputs, Derivatives, Quantitative Information [Line Items]
Price per gallon (in dollars per gal) | $ / gal	0.65