Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Renewable Energy Sales [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 198	$ 174	$ 349	$ 300
Revenues over the remaining terms of the related contacts	207		207
Natural Gas Transportation Services [Member]
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	50	$ 50	104	$ 103
Revenues over the remaining terms of the related contacts	$ 2,000		$ 2,000