Derivative Contracts Schedule Of Commodity Derivative Contracts (Details) MMBTU in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) MMBTU $ / MMBTU	Dec. 31, 2018 USD ($)
Oil Swaps [Member] | Year 2019 [Member] | NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	6.6
Average Swap Price per Unit | $	$ 55.24
Oil Swaps [Member] | Year 2019 [Member] | Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	0.7
Average Swap Price per Unit | $	$ 60.00
Oil Swaps [Member] | Year 2019 [Member] | ICE Brent [Member]
Derivative [Line Items]
Derivative Volumes	0.9
Average Swap Price per Unit | $	$ 66.73
Oil Swaps [Member] | Year 2019 [Member] | Argus WTI Houston [Member]
Derivative [Line Items]
Derivative Volumes	0.2
Average Swap Price per Unit | $	$ 65.70
Oil Swaps [Member] | Year 2020 [Member] | NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	6.2
Average Swap Price per Unit | $	$ 60.07
Oil Basis Swaps [Member] | Year 2019 [Member] | NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	3.3
Weighted-Average Differential | $ / MMBTU	(2.22)
Oil Basis Swaps [Member] | Year 2019 [Member] | NYMEX WTI less Argus WTI Houston [Member]
Derivative [Line Items]
Derivative Volumes	0.9
Weighted-Average Differential | $ / MMBTU	3.69
Oil Basis Swaps [Member] | Year 2020 [Member] | NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	4.4
Weighted-Average Differential | $ / MMBTU	(0.02)
Oil Basis Swaps [Member] | Year 2020 [Member] | NYMEX WTI less Argus WTI Houston [Member]
Derivative [Line Items]
Derivative Volumes	0.4
Weighted-Average Differential | $ / MMBTU	3.75
Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross | $	$ 17,900,000	$ 123,600,000
Fair Value, Inputs, Level 2 [Member] | Noncurrent Assets Held for Sale [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross | $		$ 300,000