Segment Disclosures Reconciliation of Segment Assets to Consolidated (Details) - USD ($) $ in Millions		Mar. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		$ 46,575	$ 45,903
Northeast G&P [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		14,388	14,397
Atlantic-Gulf [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		16,806	15,230
West [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		15,802	16,144
NGL & Petchem Services [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets		2	3
Other corporate assets [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	[1]	1,366	936
Eliminations [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	[2]	$ (1,789)	$ (807)

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

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