Summary Of Significant Accounting Policies (Schedule Of Segment's Revenues) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CVR Refining, LP | Oil and Natural Gas
Revenue, Major Customer [Line Items]
Segment's revenues	14.00%	14.00%	2.00%
Valero Energy Corporation | Oil and Natural Gas
Revenue, Major Customer [Line Items]
Segment's revenues	9.00%	10.00%	9.00%
Energy Transfer Partners (formerly Sunoco Logistics Partners) | Oil and Natural Gas
Revenue, Major Customer [Line Items]
Segment's revenues	5.00%	3.00%	10.00%
EOG Resources, Inc. | Drilling
Revenue, Major Customer [Line Items]
Segment's revenues	12.00%	5.00%	0.00%
QEP Resources, Inc. | Drilling
Revenue, Major Customer [Line Items]
Segment's revenues	12.00%	16.00%	26.00%
Slawson Exploration Company, Inc | Drilling
Revenue, Major Customer [Line Items]
Segment's revenues	11.00%	10.00%	6.00%
ONEOK, Inc. | Mid-Stream
Revenue, Major Customer [Line Items]
Segment's revenues	33.00%	45.00%	36.00%
Range Resources Corporation | Mid-Stream
Revenue, Major Customer [Line Items]
Segment's revenues	13.00%	7.00%	9.00%
Centerpoint Energy Service, Inc. | Mid-Stream
Revenue, Major Customer [Line Items]
Segment's revenues	10.00%	5.00%	4.00%