Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 2,650	$ 2,740
Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	778	711
Other non-606 revenue	7	11
Revenues	785	722
Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,712	1,811
Other non-606 revenue	153	207
Revenues	1,865	2,018
US and Utilities [Domain]
Disaggregation of Revenue [Line Items]
Revenues	1,019	1,027
US and Utilities [Domain] | Regulated Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	778	711
Other non-606 revenue	7	11
Revenues	785	722
US and Utilities [Domain] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	173	208
Other non-606 revenue	61	97
Revenues	234	305
South America [Member]
Disaggregation of Revenue [Line Items]
Revenues	845	895
South America [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
Revenues	0	0
South America [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	843	894
Other non-606 revenue	2	1
Revenues	845	895
MCAC [Member]
Disaggregation of Revenue [Line Items]
Revenues	450	408
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
Revenues	0	0
MCAC [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	429	387
Other non-606 revenue	21	21
Revenues	450	408
Eurasia - Generation [Member]
Disaggregation of Revenue [Line Items]
Revenues	339	419
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
Revenues	0	0
Eurasia - Generation [Member] | Non-regulated revenue [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	267	331
Other non-606 revenue	72	88
Revenues	339	419
Corporate Other And Other Eliminations [Member]
Disaggregation of Revenue [Line Items]
Revenues	(3)	(9)
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
Revenues	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	0	(9)
Other non-606 revenue	(3)	0
Revenues	$ (3)	$ (9)