RECENT INVESTMENT ACTIVITY (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended	9 Months Ended			9 Months Ended					9 Months Ended					9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Apr. 06, 2011 South America Acquisition [Member]	Sep. 30, 2011 South America Acquisition [Member]	Sep. 30, 2011 South America Acquisition [Member]	Apr. 30, 2010 Mexican Pipeline And Natural Gas Infrastructure Member	Sep. 30, 2011 Adjusted Allocation South America [Member]	Apr. 06, 2011 Adjusted Allocation South America [Member]		Sep. 30, 2011 Preliminary Allocation South America [Member]	Apr. 06, 2011 Preliminary Allocation South America [Member]		Apr. 06, 2011 Other Holding Companies [Member]		Sep. 30, 2011 Luz Del Sur [Member]	Sep. 13, 2011 Luz Del Sur [Member]	Sep. 06, 2011 Luz Del Sur [Member]	Apr. 06, 2011 Luz Del Sur [Member]		Sep. 30, 2011 Chilquinta Energia [Member]	Apr. 06, 2011 Chilquinta Energia [Member]		Apr. 06, 2011 Adjustments South America [Member]
Business Acquisition Line Items
Ownership Percentage Before Acquisition																				38.00%			50.00%
Acquired percentage interest in joint venture																				76.00%			100.00%
Maximum percent of Luz del Sur minority interests																			14.73%
Ownership percentage after Luz Del Sur tender offer																		79.82%
Additional shares purchased from Luz de Sur tender offer																		18,918,954
Luz Del Sur settlement of public tender offer																		$ 43
Consideration withheld related to purchase					32
Fair value of businesses acquired [Abstract]
Cash consideration (fair value of total consideration)										888			888		8					385			495
Fair value of equity method investments immediately prior to the acquisition										882			882		2					385			495
Fair value of noncontrolling interests										279			279							242			37
Total fair value of businesses acquired										2,049			2,049		10					1,012			1,027
Property, plant and equipment
Cash										245			245		4					22			219
Accounts receivable										268	[1]		266	[1]	6	[1]				101	[1]		159	[1]	2	[1]
Other current assets										39			39							19			20
Property, plant and equipment										1,486			1,485							931			554		1
Other noncurrent assets										68			66										66		2
Accounts payable										(138)			(138)							(59)			(79)
Short-term and current portion of long-term debt										(47)			(47)							(47)
Other current liabilities										(90)			(85)							(56)			(29)		(5)
Long-term debt										(484)			(473)							(179)			(294)		(11)
Other noncurrent liabilities										(268)			(268)							(178)			(90)
Total identifiable net assets										1,079			1,090		10					554			526		(11)
Goodwill										970			959							458			501		11
Acquisition-related costs (included in Other Operation and Maintenance expense in the Condensed Consolidated Statements of Operations for the nine months ended September 30, 2011)									2			2					1					1
Allowance for doubtful accounts																				1			6
Remeasurement of equity method investments			277				277
Book value of equity interests					605
Revenue of acquiree since acquisition date						345	706
Net Income of acquiree since acquisition date						60	108
Earnings of acquiree since acquisition date						52	92
Pro forma revenues	2,576	2,431	7,775	7,594
Pro forma earnings	296	146	813	793
Cash consideration (fair value of total consideration)								307
Business acquisition, Cash paid, net of cash acquired					611			292
Contributions to equity method investees				$ 65

[1] We expect acquired accounts receivable to be substantially realizable in cash. Accounts receivable are net of collection allowances of $6 million for Chile and $1 million for Peru.