Derivative Commodity Instruments - Derivative Transactions (Details) gal in Millions	6 Months Ended
	Jun. 30, 2017 MBbls gal Bcf $ / bbl $ / Mcf $ / gal
2017 | NYMEX Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | MBbls	4,020
Average Contract Price (dollars per Bbl and Gal)	50.68
2017 | NYMEX Swaps | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | Bcf	0.9
Average Contract Price (dollars per Bbl and Gal) | $ / Mcf	3.29
2017 | NYMEX Three-Way Collars | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | MBbls	2,400
2017 | Ceiling sold price (call) | Crude Oil | Short
Derivatives, Fair Value [Line Items]
Ceiling sold price (call) (dollars per Bbl)	62.18
2017 | Floor Purchased and Sold Price (Put) | Crude Oil | Short
Derivatives, Fair Value [Line Items]
Floor price (dollars per Bbl)	35.00
2017 | Floor Purchased and Sold Price (Put) | Crude Oil | Long
Derivatives, Fair Value [Line Items]
Floor price (dollars per Bbl)	45.00
2017 | WTI/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | MBbls	5,550
Average Contract Price (dollars per Bbl and Gal)	(0.66)
2017 | Liquids Swaps | Natural Gas Liquids
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | gal	41.6
Average Contract Price (dollars per Bbl and Gal) | $ / gal	0.57
2017 | Basin Specific Swaps - Permian | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | Bcf	7.8
Average Contract Price (dollars per Bbl and Gal) | $ / Mcf	2.85
2017 | Permian Swaps | Natural Gas Basis Differential
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | Bcf	0.9
Average Contract Price (dollars per Bbl and Gal) | $ / Mcf	(0.29)
2018 | NYMEX Three-Way Collars | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | MBbls	12,060
2018 | Ceiling sold price (call) | Crude Oil | Short
Derivatives, Fair Value [Line Items]
Ceiling sold price (call) (dollars per Bbl)	60.19
2018 | Floor Purchased and Sold Price (Put) | Crude Oil | Short
Derivatives, Fair Value [Line Items]
Floor price (dollars per Bbl)	36.12
2018 | Floor Purchased and Sold Price (Put) | Crude Oil | Long
Derivatives, Fair Value [Line Items]
Floor price (dollars per Bbl)	46.12
2018 | WTI/WTI Basis Swaps | Crude Oil
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | MBbls	5,760
Average Contract Price (dollars per Bbl and Gal)	(1.12)
2018 | Liquids Swaps | Natural Gas Liquids
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | gal	105.8
Average Contract Price (dollars per Bbl and Gal) | $ / gal	0.59
2018 | Basin Specific Swaps - Permian | Natural Gas
Derivatives, Fair Value [Line Items]
Total Hedged Volumes (in MBbl, Mmgal and Bcf) | Bcf	3.6
Average Contract Price (dollars per Bbl and Gal) | $ / Mcf	2.56