Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 2,625	$ 2,837	$ 7,758	$ 8,114
Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	788	759	2,272	2,176
Other non-606 revenue	11	18	36	39
Revenue	799	777	2,308	2,215
Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,654	1,898	4,964	5,336
Other non-606 revenue	172	162	486	563
Revenue	1,826	2,060	5,450	5,899
US and Utilities [Domain]
Disaggregation of Revenue [Line Items]
Revenue	1,130	1,230	3,125	3,252
US and Utilities [Domain] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	788	759	2,272	2,176
Other non-606 revenue	11	18	36	39
Revenue	799	777	2,308	2,215
US and Utilities [Domain] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	245	386	598	774
Other non-606 revenue	86	67	219	263
Revenue	331	453	817	1,037
South America [Member]
Disaggregation of Revenue [Line Items]
Revenue	828	923	2,438	2,664
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	822	922	2,429	2,661
Other non-606 revenue	6	1	9	3
Revenue	828	923	2,438	2,664
MCAC [Member]
Disaggregation of Revenue [Line Items]
Revenue	470	462	1,398	1,276
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	447	440	1,331	1,211
Other non-606 revenue	23	22	67	65
Revenue	470	462	1,398	1,276
Eurasia - Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue	197	224	801	935
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	141	152	609	701
Other non-606 revenue	56	72	192	234
Revenue	197	224	801	935
Corporate Other And Other Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue	0	(2)	(4)	(13)
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	(1)	(2)	(3)	(11)
Other non-606 revenue	1	0	(1)	(2)
Revenue	$ 0	$ (2)	$ (4)	$ (13)