Debt, Activity Under Credit Facilities (Details) - Line of Credit [Member] - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Accounts Receivable Sales Facility [Member]
Line of Credit Facility [Line Items]
Borrowings	$ 0	$ 300
IEnova Revolver [Member] \| Central Mexico Terminals [Member]
Line of Credit Facility [Line Items]
Borrowings	$ 8	$ 70

The cash inflow from a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

Name:	us-gaap_ProceedsFromShortTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration