Segment Disclosures Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions	Jun. 30, 2020		Dec. 31, 2019
Segment assets:
Total assets	$ 45,343		$ 46,040
Transmission And Gulf Of Mexico [Member]
Segment assets:
Total assets	19,569		18,796
Northeast G And P [Member]
Segment assets:
Total assets	14,609		15,399
West [Member]
Segment assets:
Total assets	10,647		11,265
Other [Member]
Segment assets:
Total assets	1,797	[1]	1,151
Intersegment Elimination [Member]
Segment assets:
Total assets	$ (1,279)		$ (571)

[1] Increase in Other Total assets is due primarily to increased cash balance.