Derivatives and Risk Management Activities - Commodity Price Risk Hedging (Details) bbl in Millions	9 Months Ended
	Sep. 30, 2020 TWh bbl MMBbls Bcf
Net long position associated with crude oil purchases
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf)	6.5
Net short time spread position hedging anticipated crude oil lease gathering purchases
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf)	4.7
Net crude oil basis spread position
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf)	3.1
Net short position related to anticipated net sales of crude oil and NGL inventory
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf)	36.5
Long natural gas position for natural gas purchases for processing and operational needs
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf) | Bcf	23.8
Short propane position related to subsequent sale of products
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf) | MMBbls	4.1
Short butane position related to subsequent sale of products
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf) | MMBbls	1.3
Short condensate WTI position related to subsequent sale of products
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf) | MMBbls	0.5
Long fuel gas position for fuel gas requirements
Commodity Price Risk Hedging:
Derivative position notional amount (in barrels, MMbls or Bcf) | Bcf	16.2
Long power position for power supply requirements
Commodity Price Risk Hedging:
Derivative position notional amount (in Terawatt hours) | TWh	0.8