Supplemental Oil and Gas Disclosures (Unaudited) (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) a	Dec. 31, 2020 USD ($) a
Oil and Gas, Acreage [Line Items]
Acquisition of mineral and royalty interest | $	$ 5,331	$ 14,181
Gross acreage	20,600	65,500
Net acreage	1,800	1,200
Mineral and Royalty Interest
Oil and Gas, Acreage [Line Items]
Gross acreage	127,800
Net acreage	59,900