Segment Disclosures Recon from Segment to Consolidated - Assets and Investments (Details) - USD ($) $ in Millions		Dec. 31, 2020	Dec. 31, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		$ 44,165	$ 46,040
Equity-method investments		5,159	6,235
Transmission And Gulf Of Mexico [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		19,110	18,796
Northeast G And P [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		14,569	15,399
West [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		10,558	11,265
Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		927	1,151
Operating Segments [Member] | Transmission And Gulf Of Mexico [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		610	741
Operating Segments [Member] | Northeast G And P [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		3,682	3,973
Operating Segments [Member] | West [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		867	1,521
Operating Segments [Member] | Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		0	0
Intersegment Eliminations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	[1]	(999)	(571)
Equity-method investments		$ 0	$ 0

[1] Eliminations primarily relate to the intercompany notes and accounts receivable generated by our cash management program.