Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Jul. 04, 2013
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	$ 637	$ 637	$ 282
Total Non Current Regulatory Assets	872	872	636
TOTAL REGULATORY ASSETS	1,509	1,509	918
Total Current Regulatory Liabilities	605	605	461
Total Non Current Regulatory Liabilities	1,509	1,509	1,592
Total period for adjustments to the Regulatory Asset Base	4 years
TOTAL REGULATORY LIABILITIES	2,114	2,114	2,053
Period of annual tariff adjustment		12 months
Total period to recover or refund costs for annual tariff adjustment	2 years	24 months
Brazil Tariff Estimated Rate Change Liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	76	76	245
Total Non Current Regulatory Liabilities	0	0	82
Tariff adjustment, percentage amortized				67.55%
Tariff adjustment, percentage amortized in next tariff adjustment				32.45%
Efficiency Program Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	22	22	25
Total Non Current Regulatory Liabilities	11	11	10
Brazil Regulatory Asset Base Adjustment
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	123	123	34
Total Non Current Regulatory Liabilities	61	61	235
Brazil Tariff Recoveries Energy Purchases Liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	144	144	48
Total Non Current Regulatory Liabilities	128	128	16
Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Liability
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	174	174	69
Total Non Current Regulatory Liabilities	97	97	42
Asset Retirement Obligation Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Liabilities	727	727	696
Brazil Special Obligations
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Liabilities	484	484	502
Other Regulatory Liabilities
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Liabilities	66	66	40
Total Non Current Regulatory Liabilities	1	1	9
Brazil Tariff Recoveries Energy Purchases Asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	424	424	87
Total Non Current Regulatory Assets	266	266	62
Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	63	63	52
Total Non Current Regulatory Assets	14	14	4
El Salvador Tariff Recoveries
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	92	92	108
Pension Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets	329	329	261
Income Taxes Recoverable From Customers
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets	74	74	72
Deferred Midwest Independent Service Operator Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Non Current Regulatory Assets	111	111	98
Other Regulatory Assets
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	58	58	35
Total Non Current Regulatory Assets	78	78	139
Other current regulatory assets that did not earn a rate of return	22	22	13
Other noncurrent regulatory assets that did not earn a rate of return	$ 73	$ 73	$ 71