Equity Investments (Schedule of Equity Investment Earnings (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 104	$ 137	$ 240	$ 256
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	30	58	87	109
Bayou Bridge Pipeline, LLC (Bayou Bridge)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	7	8	17	12
DCP Sand Hills Pipeline, LLC (Sand Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	37	38	78	74
DCP Southern Hills Pipeline, LLC (Southern Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	10	11	21	24
Explorer Pipeline Company (Explorer)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	4	11	11	14
Gray Oak Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	14	0	19	0
Liberty Pipeline LLC (Liberty)
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	2	3	6	6
Phillips 66 Partners Terminal LLC (Phillips 66 Partners Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	(1)	6	(1)	12
South Texas Gateway Terminal LLC (South Texas Gateway Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	0	0	0	0
STACK Pipeline LLC (STACK)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 1	$ 2	$ 2	$ 5