Oil And Natural Gas Properties And Related Equipment (DDA and Impairments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Amortization of intangible assets	$ 13,460	$ 13,460
Depreciation and depletion	11,873	12,527
Asset impairments	32,119
Exploration and dry hole costs	$ 0	0
Furniture and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful lives	3 years
Furniture and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful lives	15 years
Gathering Facilities | Maximum
Property, Plant and Equipment [Line Items]
Useful lives	36 years
Transportation assets | Maximum
Property, Plant and Equipment [Line Items]
Useful lives	40 years
Oil and Natural Gas-Related Assets
Property, Plant and Equipment [Line Items]
Depreciation and depletion	$ 3,942	4,798
Gathering and Transportation Related Assets
Property, Plant and Equipment [Line Items]
Depreciation and depletion	7,931	7,729
Oil and Natural Gas-Related Assets and Gathering and Transportation-Related Assets
Property, Plant and Equipment [Line Items]
Total Depreciation, depletion and amortization	25,333	25,987
Seco Pipeline, LLC
Property, Plant and Equipment [Line Items]
Asset impairments	$ 32,100	$ 0