Derivative And Financial Instruments (Hedges In Place) (Details)	3 Months Ended
	Mar. 31, 2017 $ / bbl bbl
West Texas Intermediate 2017 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	94,005
Average Price | $ / bbl	61.25
West Texas Intermediate 2017 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	87,304
Average Price | $ / bbl	61.42
West Texas Intermediate 2017 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	81,702
Average Price | $ / bbl	61.55
West Texas Intermediate 2017
Derivative [Line Items]
Volume (in Bbls)	263,011
Average Price | $ / bbl	61.40
West Texas Intermediate 2018 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	88,854
Average Price | $ / bbl	60.82
West Texas Intermediate 2018 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	83,976
Average Price | $ / bbl	60.90
West Texas Intermediate 2018 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	79,683
Average Price | $ / bbl	60.96
West Texas Intermediate 2018 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	75,864
Average Price | $ / bbl	61.02
West Texas Intermediate 2018
Derivative [Line Items]
Volume (in Bbls)	328,377
Average Price | $ / bbl	60.92
West Texas Intermediate 2019 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	78,667
Average Price | $ / bbl	61.48
West Texas Intermediate 2019 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	75,326
Average Price | $ / bbl	61.53
West Texas Intermediate 2019 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	72,279
Average Price | $ / bbl	61.57
West Texas Intermediate 2019 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	69,480
Average Price | $ / bbl	61.61
West Texas Intermediate 2019
Derivative [Line Items]
Volume (in Bbls)	295,752
Average Price | $ / bbl	61.54
West Texas Intermediate 2020 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	66,914
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	64,477
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	62,251
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	60,224
Average Price | $ / bbl	53.50
West Texas Intermediate 2020
Derivative [Line Items]
Volume (in Bbls)	253,866
Average Price | $ / bbl	53.50
West Texas Intermediate
Derivative [Line Items]
Volume (in Bbls)	1,141,006
NYMEX 2017 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	287,439
Average Price | $ / bbl	5.45
NYMEX 2017 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	271,368
Average Price | $ / bbl	5.45
NYMEX 2017 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	257,234
Average Price | $ / bbl	5.45
NYMEX 2017
Derivative [Line Items]
Volume (in Bbls)	816,041
Average Price | $ / bbl	5.45
NYMEX 2018 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	260,841
Average Price | $ / bbl	3.18
NYMEX 2018 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	248,018
Average Price | $ / bbl	3.18
NYMEX 2018 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	235,810
Average Price | $ / bbl	3.18
NYMEX 2018 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	225,208
Average Price | $ / bbl	3.18
NYMEX 2018
Derivative [Line Items]
Volume (in Bbls)	969,877
Average Price | $ / bbl	3.18
NYMEX 2019 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	224,303
Average Price | $ / bbl	3.10
NYMEX 2019 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	214,186
Average Price | $ / bbl	3.10
NYMEX 2019 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	205,533
Average Price | $ / bbl	3.10
NYMEX 2019 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	197,455
Average Price | $ / bbl	3.10
NYMEX 2019
Derivative [Line Items]
Volume (in Bbls)	841,477
Average Price | $ / bbl	3.10
NYMEX 2020 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls)	188,696
Average Price | $ / bbl	2.85
NYMEX 2020 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls)	176,946
Average Price | $ / bbl	2.85
NYMEX 2020 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls)	170,637
Average Price | $ / bbl	2.85
NYMEX 2020 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls)	164,747
Average Price | $ / bbl	2.85
NYMEX 2020
Derivative [Line Items]
Volume (in Bbls)	701,026
Average Price | $ / bbl	2.85
NYMEX
Derivative [Line Items]
Volume (in Bbls)	3,328,421