Financial Instruments and Risk Management (Narrative) (Details) barrels_per_day in Thousands, $ in Millions	2 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended	24 Months Ended
	Jun. 30, 2020 barrels_per_day $ / bbl	Mar. 31, 2021 USD ($) barrels_per_day contract OffsettingPosition $ / bbl	Mar. 31, 2020 barrels_per_day contract	Dec. 31, 2020 barrels_per_day OffsettingPosition $ / bbl	Dec. 31, 2021 barrels_per_day $ / bbl	Dec. 31, 2019 Acquisition
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of foreign currency derivatives (in contracts) | contract		0	0
Amount of loss reclassified to interest expense | $		$ (2.1)
Number of businesses acquired (in acquisitions) | Acquisition						2
Number of offsetting positions (in offsetting positions) | OffsettingPosition		0		0
Commodity derivative contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Daily production commitment (barrels per day) | barrels_per_day	65	45	45	45
Average forward price (in dollars per barrel) | $ / bbl	47.20	42.77		56.42
Notes Due 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Debt instrument term		10 years
Forecast | Commodity derivative contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Average forward price (in dollars per barrel) | $ / bbl					44.88
Forecast | Commodity derivative contracts | Subsequent Event
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Daily production commitment (barrels per day) | barrels_per_day					20