Other Income and Expense (Nonoperating Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liquidation Basis of Accounting, Remeasurement, Gain (Loss) on Asset		$ 0		$ 0
Total other income	$ 72	120		64
Other Income [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Litigation Settlement, Amount Awarded from Other Party	0	60	[1]	0
Public Utilities, Allowance for Funds Used During Construction, Additions	8	26		29
Gain (Loss) on Disposition of Other Assets	4	1		4
Other	28	33		31
Total other income	$ 72	$ 120		$ 64

[1] In December 2016, the Company and YPF entered into a settlement in which all parties agreed to give up any and all legal action related to gas supply contracts that were terminated in 2008 and have been in dispute since 2009. In January 2017, the YPF board approved the agreement and paid the Company $60 million, thereby resolving all uncertainties around the dispute.