Supplemental Information on Oil and Natural Gas Operations (Unaudited) Average First-Day-of-the-Month Price for Oil, Natural Gas and Natural Gas Liquids (Details)	12 Months Ended
	Dec. 31, 2018 $ / Mcf $ / bbl	Dec. 31, 2017 $ / Mcf $ / bbl	Dec. 31, 2016 $ / Mcf $ / bbl
Oil [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Unweighted Arithmetic Average First-Day-of-the-Month Prices	61.46	48.21	39.64
Natural Gas [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Unweighted Arithmetic Average First-Day-of-the-Month Prices | $ / Mcf	1.84	2.13	1.36
Natural Gas Liquids [Member]
Average Sales Price and Production Costs Per Unit of Production [Line Items]
Unweighted Arithmetic Average First-Day-of-the-Month Prices	25.04	19.15	11.69