Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Balance as of January 1	$ 2,464	$ 2,293
Goodwill attributable to Gas Storage and Pipelines 2019 acquisition of Blue Union and LEAP	2	171
Balance at December 31	$ 2,466	$ 2,464