Revenue (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue		$ 2,217	$ 2,483	$ 4,555	$ 5,133
Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		610	706	1,313	1,484
Other non-606 revenue		14	18	23	25
Revenue		624	724	1,336	1,509
Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		1,419	1,598	2,870	3,310
Other non-606 revenue	[1]	174	161	349	314
Revenue		1,593	1,759	3,219	3,624
US and Utilities [Domain]
Disaggregation of Revenue [Line Items]
Revenue		913	976	1,884	1,995
US and Utilities [Domain] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		610	706	1,313	1,484
Other non-606 revenue		14	18	23	25
Revenue		624	724	1,336	1,509
US and Utilities [Domain] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax		201	180	364	353
Other non-606 revenue	[1]	88	72	184	133
Revenue		289	252	548	486
South America [Member]
Disaggregation of Revenue [Line Items]
Revenue		711	765	1,423	1,610
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		708	764	1,419	1,607
Other non-606 revenue	[1]	3	1	4	3
Revenue		711	765	1,423	1,610
MCAC [Member]
Disaggregation of Revenue [Line Items]
Revenue		381	478	813	928
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		356	455	764	884
Other non-606 revenue	[1]	25	23	49	44
Revenue		381	478	813	928
Eurasia - Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue		214	265	439	604
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		156	201	327	468
Other non-606 revenue	[1]	58	64	112	136
Revenue		214	265	439	604
Corporate Other And Other Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenue		(2)	(1)	(4)	(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		(2)	(2)	(4)	(2)
Other non-606 revenue	[1]	0	1	0	(2)
Revenue		$ (2)	$ (1)	$ (4)	$ (4)

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