Revenue (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue		$ 2,545	$ 2,625	$ 7,100	$ 7,758
Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		674	788	1,987	2,272
Other non-606 revenue		6	11	29	36
Revenue		680	799	2,016	2,308
Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,774	1,654	4,644	4,964
Other non-606 revenue	[1]	91	172	440	486
Revenue		1,865	1,826	5,084	5,450
US and Utilities [Domain]
Disaggregation of Revenue [Line Items]
Revenue		1,061	1,130	2,945	3,125
US and Utilities [Domain] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		674	788	1,987	2,272
Other non-606 revenue		6	11	29	36
Revenue		680	799	2,016	2,308
US and Utilities [Domain] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		378	245	742	598
Other non-606 revenue	[1]	3	86	187	219
Revenue		381	331	929	817
South America [Member]
Disaggregation of Revenue [Line Items]
Revenue		850	828	2,273	2,438
South America [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0	0	0
Other non-606 revenue		0	0	0	0
Revenue		0	0	0	0
South America [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		848	822	2,267	2,429
Other non-606 revenue	[1]	2	6	6	9
Revenue		850	828	2,273	2,438
MCAC [Member]
Disaggregation of Revenue [Line Items]
Revenue		442	470	1,255	1,398
MCAC [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0	0	0
Other non-606 revenue		0	0	0	0
Revenue		0	0	0	0
MCAC [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		417	447	1,181	1,331
Other non-606 revenue	[1]	25	23	74	67
Revenue		442	470	1,255	1,398
Eurasia - Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue		195	197	634	801
Eurasia - Generation [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0	0	0
Other non-606 revenue		0	0	0	0
Revenue		0	0	0	0
Eurasia - Generation [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		134	141	461	609
Other non-606 revenue	[1]	61	56	173	192
Revenue		195	197	634	801
Corporate Other And Other Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue		(3)	0	(7)	(4)
Corporate Other And Other Eliminations [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0	0	0
Other non-606 revenue		0	0	0	0
Revenue		0	0	0	0
Corporate Other And Other Eliminations [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		(3)	(1)	(7)	(3)
Other non-606 revenue	[1]	0	1	0	(1)
Revenue		$ (3)	$ 0	$ (7)	$ (4)

[1] Other non-regulated revenue primarily includes lease and derivative revenue not accounted for under ASC 606.