Derivative Contracts Schedule Of Commodity Derivative Contracts (Details) MMBTU in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) MMBTU $ / MMBTU	Dec. 31, 2018 USD ($)
Oil Swaps [Member] | Year 2019 [Member] | NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	9.5
Average Swap Price per Unit | $	$ 54.93
Oil Swaps [Member] | Year 2019 [Member] | ICE Brent [Member]
Derivative [Line Items]
Derivative Volumes	1.1
Average Swap Price per Unit | $	$ 66.54
Oil Swaps [Member] | Year 2020 [Member] | NYMEX WTI [Member]
Derivative [Line Items]
Derivative Volumes	5.1
Average Swap Price per Unit | $	$ 60.01
Oil Basis Swaps [Member] | Year 2019 [Member] | NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	5.0
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	0.6
Weighted-Average Differential | $ / MMBTU	3.75
Oil Basis Swaps [Member] | Year 2020 [Member] | NYMEX WTI less Argus WTI Midland [Member]
Derivative [Line Items]
Derivative Volumes	2.6
Weighted-Average Differential | $ / MMBTU	(0.46)
Fair Value, Inputs, Level 2 [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross | $	$ 6,700,000	$ 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