Equity Investments and Loans (Schedule of Equity Investment Earnings (Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 136	$ 119
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	57	51
Bayou Bridge Pipeline, LLC (Bayou Bridge)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	10	4
DCP Sand Hills Pipeline, LLC (Sand Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	41	36
DCP Southern Hills Pipeline, LLC (Southern Hills)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	11	13
Explorer Pipeline Company (Explorer)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	7	3
Gray Oak Pipeline, LLC
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	5	0
Liberty Pipeline LLC (Liberty)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	0	0
Paradigm Pipeline LLC (Paradigm)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	4	3
Phillips 66 Partners Terminal LLC (Phillips 66 Partners Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	0	6
South Texas Gateway Terminal LLC (South Texas Gateway Terminal)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	0	0
STACK Pipeline LLC (STACK)
Schedule of Equity Method Investments [Line Items]
Total equity in earnings of affiliates	$ 1	$ 3