Reportable Segments Segment Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	[1]	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 97,522	$ 102,294		$ 88,609
Intrastate transportation and storage
Segment Reporting Information [Line Items]
Assets	7,215	6,648
Interstate transportation and storage
Segment Reporting Information [Line Items]
Assets	17,341	18,111
Midstream
Segment Reporting Information [Line Items]
Assets	19,056	20,332
NGL and refined products transportation and services
Segment Reporting Information [Line Items]
Assets	20,944	19,145
Crude oil transportation and services
Segment Reporting Information [Line Items]
Assets	19,882	22,933
Investment In Sunoco LP [Member]
Segment Reporting Information [Line Items]
Assets	4,986	5,438
Investment In USAC [Member]
Segment Reporting Information [Line Items]
Assets	3,011	3,730
All other
Segment Reporting Information [Line Items]
Assets	$ 5,087	$ 5,957

[1] *As adjusted. See Note 1.