Revenue (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue		$ 2,635	$ 2,338
Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		698	703
Other non-606 revenue		9	9
Revenue		707	712
Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,823	1,451
Other non-606 revenue	[1]	105	175
Revenue		1,928	1,626
US and Utilities [Domain]
Disaggregation of Revenue [Line Items]
Revenue		949	971
US and Utilities [Domain] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		698	703
Other non-606 revenue		9	9
Revenue		707	712
US and Utilities [Domain] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		224	163
Other non-606 revenue	[1]	18	96
Revenue		242	259
MCAC [Member]
Disaggregation of Revenue [Line Items]
Revenue		535	432
MCAC [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0
Other non-606 revenue		0	0
Revenue		0	0
MCAC [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		510	408
Other non-606 revenue	[1]	25	24
Revenue		535	432
Eurasia - Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue		270	225
Eurasia - Generation [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0
Other non-606 revenue		0	0
Revenue		0	0
Eurasia - Generation [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		209	171
Other non-606 revenue	[1]	61	54
Revenue		270	225
Corporate Other And Other Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue		(3)	(2)
Corporate Other And Other Eliminations [Member] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0
Other non-606 revenue		0	0
Revenue		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)	(2)
Other non-606 revenue	[1]	0	0
Revenue		(3)	(2)
South American SBU
Disaggregation of Revenue [Line Items]
Revenue		884	712
South American SBU | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		0	0
Other non-606 revenue		0	0
Revenue		0	0
South American SBU | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		883	711
Other non-606 revenue	[1]	1	1
Revenue		$ 884	$ 712

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