Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Mar. 20, 2018
Income Tax Disclosures [Line Items]
Effective Income Tax Rate Reconciliation, Percent	39.00%		38.00%	27.00%	40.00%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%	35.00%
One-time Transition Tax Rate				15.50%
Gain (Loss) on Disposition of Business	$ (89)		$ 48	$ (877)	$ 48
Proceeds from Divestiture of Businesses and Interests in Affiliates				$ 1,808	$ 33
Electrica Santiago (Gener ESSA) [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Tax Disclosures [Line Items]
Gain (Loss) on Disposition of Business	89
Tax on gain (loss) on disposition of business		$ 31
Proceeds from Divestiture of Businesses and Interests in Affiliates	$ 307
Masinloc Subsidiary [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Tax Disclosures [Line Items]
Gain (Loss) on Disposition of Business		777
Tax on gain (loss) on disposition of business		155
Proceeds from Divestiture of Businesses and Interests in Affiliates		$ 1,050
Masinloc Subsidiary [Member]
Income Tax Disclosures [Line Items]
Disposal Group Not Discontinued Operation Ownership Interest Sold						51.00%