Financial Instruments and Risk Management (Narrative) (Details) barrels_per_day in Thousands, $ in Millions	9 Months Ended	12 Months Ended	24 Months Ended
	Sep. 30, 2021 USD ($) barrels_per_day contract OffsettingPosition $ / bbl	Dec. 31, 2021 barrels_per_day $ / bbl	Dec. 31, 2019 Acquisition	Dec. 31, 2020 OffsettingPosition	Sep. 30, 2020 contract
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of loss reclassified to interest expense | $	$ (2.1)
Number of foreign currency derivatives (in contracts) | contract	0				0
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	45
Average forward price (in dollars per barrel) | $ / bbl	42.77
Forecast | Commodity derivative contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Daily production commitment (barrels per day) | barrels_per_day		20
Average forward price (in dollars per barrel) | $ / bbl		44.88