Derivative And Financial Instruments (Hedges In Place) (Details)	9 Months Ended
	Sep. 30, 2017 MMBTU $ / bbl $ / MMBTU bbl
West Texas Intermediate 2017 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls) | bbl	64,568
Average Price | $ / bbl	59.83
West Texas Intermediate 2017
Derivative [Line Items]
Volume (in Bbls) | bbl	64,568
Average Price | $ / bbl	59.83
West Texas Intermediate 2018 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls) | bbl	70,600
Average Price | $ / bbl	59.63
West Texas Intermediate 2018 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls) | bbl	66,432
Average Price | $ / bbl	59.71
West Texas Intermediate 2018 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls) | bbl	62,840
Average Price | $ / bbl	59.78
West Texas Intermediate 2018 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls) | bbl	59,704
Average Price | $ / bbl	59.84
West Texas Intermediate 2018
Derivative [Line Items]
Volume (in Bbls) | bbl	259,576
Average Price | $ / bbl	59.74
West Texas Intermediate 2019 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls) | bbl	62,528
Average Price | $ / bbl	60.41
West Texas Intermediate 2019 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls) | bbl	59,552
Average Price | $ / bbl	60.44
West Texas Intermediate 2019 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls) | bbl	57,024
Average Price | $ / bbl	60.48
West Texas Intermediate 2019 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls) | bbl	54,824
Average Price | $ / bbl	60.52
West Texas Intermediate 2019
Derivative [Line Items]
Volume (in Bbls) | bbl	233,928
Average Price | $ / bbl	60.46
West Texas Intermediate 2020 Swap Quarter 1
Derivative [Line Items]
Volume (in Bbls) | bbl	52,776
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 2
Derivative [Line Items]
Volume (in Bbls) | bbl	50,960
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 3
Derivative [Line Items]
Volume (in Bbls) | bbl	49,224
Average Price | $ / bbl	53.50
West Texas Intermediate 2020 Swap Quarter 4
Derivative [Line Items]
Volume (in Bbls) | bbl	47,624
Average Price | $ / bbl	53.50
West Texas Intermediate 2020
Derivative [Line Items]
Volume (in Bbls) | bbl	200,584
Average Price | $ / bbl	53.50
West Texas Intermediate
Derivative [Line Items]
Volume (in Bbls) | bbl	758,656
NYMEX 2017 Swap Quarter 4
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	124,160
Average Price | $ / MMBTU	3.79
NYMEX 2017
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	124,160
Average Price | $ / MMBTU	3.79
NYMEX 2018 Swap Quarter
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	132,088
Average Price | $ / MMBTU	3.00
NYMEX 2018 Swap Quarter 2
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	126,600
Average Price | $ / MMBTU	3.00
NYMEX 2018 Swap Quarter 3
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	121,600
Average Price | $ / MMBTU	3.00
NYMEX 2018 Swap Quarter 4
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	117,040
Average Price | $ / MMBTU	3.00
NYMEX 2018
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	497,328
Average Price | $ / MMBTU	3.00
NYMEX 2019 Swap Quarter 1
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	119,832
Average Price | $ / MMBTU	2.85
NYMEX 2019 Swap Quarter 2
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	115,784
Average Price | $ / MMBTU	2.85
NYMEX 2019 Swap Quarter 3
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	112,032
Average Price | $ / MMBTU	2.85
NYMEX 2019 Swap Quarter 4
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	108,552
Average Price | $ / MMBTU	2.85
NYMEX 2019
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	456,200
Average Price | $ / MMBTU	2.85
NYMEX 2020 Swap Quarter 1
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	105,104
Average Price | $ / MMBTU	2.85
NYMEX 2020 Swap Quarter 2
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	102,008
Average Price | $ / MMBTU	2.85
NYMEX 2020 Swap Quarter 3
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	99,136
Average Price | $ / MMBTU	2.85
NYMEX 2020 Swap Quarter 4
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	96,200
Average Price | $ / MMBTU	2.85
NYMEX 2020
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	402,448
Average Price | $ / MMBTU	2.85
NYMEX
Derivative [Line Items]
Volume (in MMBtu) | MMBTU	1,480,136