Derivatives and Risk Management Activities - Offsetting Asset and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivative Asset Positions
Effect of Collateral Netting		$ (45)
Derivative Liability Positions
Effect of Collateral Netting	$ 45
Commodity Derivatives
Derivative Asset Positions
Effect of Collateral Netting		(45)
Derivative Liability Positions
Gross Position - Asset	369	235
Gross Position - Liability	(286)	(105)
Effect of Collateral Netting	45
Net Carrying Value Presented on the Balance Sheet, Total	128	85
Other current assets | Commodity Derivatives
Derivative Asset Positions
Gross Position - Asset	171	179
Gross Position - Liability	(83)	(37)
Effect of Collateral Netting		(45)
Net Carrying Value Presented on the Balance Sheet	127	97
Derivative Liability Positions
Effect of Collateral Netting	39
Other long-term assets, net | Commodity Derivatives
Derivative Asset Positions
Gross Position - Asset	64	24
Gross Position - Liability	(3)
Net Carrying Value Presented on the Balance Sheet	61	24
Other current liabilities | Commodity Derivatives
Derivative Liability Positions
Gross Position - Asset	118	32
Gross Position - Liability	(149)	(56)
Effect of Collateral Netting	6
Net Carrying Value Presented on the Balance Sheet	(25)	(24)
Other long-term liabilities and deferred credits | Commodity Derivatives
Derivative Liability Positions
Gross Position - Asset	16
Gross Position - Liability	(51)	(12)
Net Carrying Value Presented on the Balance Sheet	$ (35)	$ (12)