Equity Investments (Schedule of Equity Investment Earnings (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 129	$ 139	$ 369	$ 395
Dakota Access, LLC and Energy Transfer Crude Oil Company, LLC (Bakken Pipeline)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	37	58	124	167
Bayou Bridge Pipeline, LLC (Bayou Bridge)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	6	9	23	21
DCP Sand Hills Pipeline, LLC (Sand Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	33	39	111	113
DCP Southern Hills Pipeline, LLC (Southern Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	11	10	32	34
Explorer Pipeline Company (Explorer)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	6	12	17	26
Gray Oak Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	30	(2)	49	(2)
Liberty Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	0	0	0	0
Paradigm Pipeline LLC (Paradigm)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	4	4	10	10
Phillips 66 Partners Terminal LLC (Phillips 66 Partners Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	(1)	6	(2)	18
South Texas Gateway Terminal LLC (South Texas Gateway Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	2	0	2	0
STACK Pipeline LLC (STACK)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 1	$ 3	$ 3	$ 8