Segment Disclosures Recon from Segment to Consolidated - Assets and Investments (Details) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		$ 45,302	$ 46,352
Equity-method investments		7,821	6,552
Northeast G And P [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		14,526	14,397
Atlantic Gulf [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		16,346	14,989
West [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		13,948	16,143
Other [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	[1]	849	1,449
Operating Segments [Member] | Northeast G And P [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		5,319	5,307
Operating Segments [Member] | Atlantic Gulf [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		776	823
Operating Segments [Member] | West [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Equity-method investments		1,726	422
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	[2]	(367)	(626)
Equity-method investments		$ 0	$ 0

[1] (1)Decrease in Other is due primarily to a decreased cash balance.

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