Commodity Derivative Contracts (Commodity Derivatives Outstanding Table) (Details)	Mar. 31, 2019 bbl / d $ / Barrel
Swap | Year 2019 | Q2 | NYMEX
Derivative [Line Items]
Volume per day | bbl / d	3,500
Weighted average swap price	59.05
Swap | Year 2019 | Q2 | NYMEX | Minimum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	59.00
Swap | Year 2019 | Q2 | NYMEX | Maximum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	59.10
Swap | Year 2019 | Q2-Q4 | LLS
Derivative [Line Items]
Volume per day | bbl / d	13,000
Weighted average swap price	64.69
Swap | Year 2019 | Q2-Q4 | LLS | Minimum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	60.00
Swap | Year 2019 | Q2-Q4 | LLS | Maximum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	74.90
Swap | Year 2020 | LLS
Derivative [Line Items]
Volume per day | bbl / d	2,000
Weighted average swap price	60.89
Swap | Year 2020 | LLS | Minimum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	60.72
Swap | Year 2020 | LLS | Maximum
Derivative [Line Items]
Derivative, Swap Type, Fixed Price	61.05
Three-way Collar | Year 2019 | Q2 | NYMEX
Derivative [Line Items]
Volume per day | bbl / d	18,500
Weighted average sold put price	48.84
Weighted average floor price	56.84
Weighted average ceiling price	69.94
Three-way Collar | Year 2019 | Q2 | NYMEX | Minimum
Derivative [Line Items]
Derivative, Floor Price	55.00
Three-way Collar | Year 2019 | Q2 | NYMEX | Maximum
Derivative [Line Items]
Derivative, Cap Price	75.45
Three-way Collar | Year 2019 | Q2 | LLS
Derivative [Line Items]
Volume per day | bbl / d	5,500
Weighted average sold put price	54.73
Weighted average floor price	63.09
Weighted average ceiling price	79.93
Three-way Collar | Year 2019 | Q2 | LLS | Minimum
Derivative [Line Items]
Derivative, Floor Price	62.00
Three-way Collar | Year 2019 | Q2 | LLS | Maximum
Derivative [Line Items]
Derivative, Cap Price	86.00
Three-way Collar | Year 2019 | Q3-Q4 | NYMEX
Derivative [Line Items]
Volume per day | bbl / d	22,000
Weighted average sold put price	48.55
Weighted average floor price	56.55
Weighted average ceiling price	69.17
Three-way Collar | Year 2019 | Q3-Q4 | NYMEX | Minimum
Derivative [Line Items]
Derivative, Floor Price	55.00
Three-way Collar | Year 2019 | Q3-Q4 | NYMEX | Maximum
Derivative [Line Items]
Derivative, Cap Price	75.45
Three-way Collar | Year 2019 | Q3-Q4 | LLS
Derivative [Line Items]
Volume per day | bbl / d	5,500
Weighted average sold put price	54.73
Weighted average floor price	63.09
Weighted average ceiling price	79.93
Three-way Collar | Year 2019 | Q3-Q4 | LLS | Minimum
Derivative [Line Items]
Derivative, Floor Price	62.00
Three-way Collar | Year 2019 | Q3-Q4 | LLS | Maximum
Derivative [Line Items]
Derivative, Cap Price	86.00
Three-way Collar | Year 2020 | Q1-Q2 | NYMEX
Derivative [Line Items]
Volume per day | bbl / d	8,000
Weighted average sold put price	49.21
Weighted average floor price	58.86
Weighted average ceiling price	66.69
Three-way Collar | Year 2020 | Q1-Q2 | NYMEX | Minimum
Derivative [Line Items]
Derivative, Floor Price	57.50
Three-way Collar | Year 2020 | Q1-Q2 | NYMEX | Maximum
Derivative [Line Items]
Derivative, Cap Price	82.65
Three-way Collar | Year 2020 | Q1-Q2 | LLS
Derivative [Line Items]
Volume per day | bbl / d	3,000
Weighted average sold put price	53.83
Weighted average floor price	63.83
Weighted average ceiling price	73.93
Three-way Collar | Year 2020 | Q1-Q2 | LLS | Minimum
Derivative [Line Items]
Derivative, Floor Price	62.50
Three-way Collar | Year 2020 | Q1-Q2 | LLS | Maximum
Derivative [Line Items]
Derivative, Cap Price	87.10
Three-way Collar | Year 2020 | Q3-Q4 | NYMEX
Derivative [Line Items]
Volume per day | bbl / d	6,000
Weighted average sold put price	49.59
Weighted average floor price	59.13
Weighted average ceiling price	67.47
Three-way Collar | Year 2020 | Q3-Q4 | NYMEX | Minimum
Derivative [Line Items]
Derivative, Floor Price	58.25
Three-way Collar | Year 2020 | Q3-Q4 | NYMEX | Maximum
Derivative [Line Items]
Derivative, Cap Price	82.65
Three-way Collar | Year 2020 | Q3-Q4 | LLS
Derivative [Line Items]
Volume per day | bbl / d	1,000
Weighted average sold put price	55.00
Weighted average floor price	65.00
Weighted average ceiling price	86.80
Three-way Collar | Year 2020 | Q3-Q4 | LLS | Minimum
Derivative [Line Items]
Derivative, Floor Price	65.00
Three-way Collar | Year 2020 | Q3-Q4 | LLS | Maximum
Derivative [Line Items]
Derivative, Cap Price	87.10