Commitments and Contingencies (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Mid-Stream [Member]
Long-term Purchase Commitment [Line Items]
Other Commitment, Due in Next Twelve Months	$ 1,000
Other Commitment, Due in Second and Third Year	$ 600
Capital Addition Purchase Commitments [Member] | Oil and Natural Gas [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Description	as part of the Superior transaction, we entered into a contractual obligation that commits us to spend $150.0 million to drill wells in the Granite Wash/Buffalo Wallow area over three years starting January 1, 2019. For each dollar of the $150.0 million we do not spend (over the three-year period), we would forgo receiving $0.58 of future distributions from our 50% ownership interest in our consolidated mid-stream subsidiary. At June 30, 2020, if we elected not to drill or spend any additional money in the designated area before December 31, 2021, the maximum amount we could forgo from distributions would be $72.6 million.
Long-term purchase commitment, purchases made	$ 24,800