Oil And Natural Gas Properties And Related Equipment (DDA and Impairments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Amortization of intangible assets			$ 10,204	$ 10,345
Depreciation, depletion and amortization			17,813	11,341
Asset impairments			4,688	1,309
Total	$ 6,899	$ 7,507	32,705	22,133
Non-cash impairment charges	0	0	4,700	1,300
Proved property	200,422		200,422		$ 758,366
Exploration and dry hole costs			$ 0	0
Gathering Facilities
Property, Plant and Equipment [Line Items]
Useful lives			36 years
Oil and Natural Gas-Related Assets
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	1,739	2,348	$ 7,850	5,310
Gathering and Transportation Related Assets
Property, Plant and Equipment [Line Items]
Depreciation, depletion and amortization	1,780	1,731	$ 9,963	5,169
Gathering and Transportation Related Assets | Minimum
Property, Plant and Equipment [Line Items]
Useful lives			3 years
Gathering and Transportation Related Assets | Maximum
Property, Plant and Equipment [Line Items]
Useful lives			15 years
Oil and Natural Gas-Related Assets and Gathering and Transportation-Related Assets
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	3,380	3,428	$ 10,204	10,345
Depreciation, depletion and amortization	$ 6,899	$ 7,507	$ 28,017	$ 20,824