Segments (Details) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Revenue
Total Revenue	$ 4,544	$ 3,923	$ 8,808	$ 7,843
Intersegment	0	0	0	0
Reconciliation To Income From Continuing Operations Before Taxes
Depreciation and amortization	311	273	607	539
Interest expense	(396)	(389)	(747)	(770)
Interest income	97	101	192	209
Other expense	(38)	(48)	(55)	(60)
Other income	34	68	50	77
Gain on sale of investments	1	0	7	0
Asset impairment expense	(33)	(1)	(33)	(1)
Foreign currency transaction gains (losses) on net monetary position	38	(71)	71	(122)
Other non-operating expense	0	(5)	0	(5)
Income from continuing operations before taxes and equity in earnings of affiliates	625	556	1,328	1,110
Assets
Total Assets	42,635		42,635		40,511
Latin America Generation [Member]
Revenue
Total Revenue	1,377	1,084	2,508	2,067
Intersegment	(263)	(256)	(514)	(511)
External Revenue	1,114	828	1,994	1,556
Adjusted Gross Margin
Adjusted Gross Margin	518	466	988	860
Intersegment	(248)	(253)	(487)	(504)
External Adjusted Gross Margin	270	213	501	356
Assets
Total Assets	10,584		10,584		10,373
Latin America Utilities [Member]
Revenue
Total Revenue	2,013	1,770	3,917	3,535
Intersegment	0	0	0	0
External Revenue	2,013	1,770	3,917	3,535
Adjusted Gross Margin
Adjusted Gross Margin	363	320	704	619
Intersegment	253	256	498	511
External Adjusted Gross Margin	616	576	1,202	1,130
Assets
Total Assets	10,344		10,344		10,081
North America Generation [Member]
Revenue
Total Revenue	372	369	744	760
Intersegment	(4)	0	(4)	0
External Revenue	368	369	740	760
Adjusted Gross Margin
Adjusted Gross Margin	131	122	257	260
Intersegment	(1)	3	3	7
External Adjusted Gross Margin	130	125	260	267
Assets
Total Assets	4,403		4,403		4,681
North America Utilities Member
Revenue
Total Revenue	280	275	569	563
Intersegment	0	0	0	0
External Revenue	280	275	569	563
Adjusted Gross Margin
Adjusted Gross Margin	89	93	179	206
Intersegment	1	1	1	1
External Adjusted Gross Margin	90	94	180	207
Assets
Total Assets	3,182		3,182		3,139
Europe Generation [Member]
Revenue
Total Revenue	328	260	728	582
Intersegment	0	0	(1)	0
External Revenue	328	260	727	582
Adjusted Gross Margin
Adjusted Gross Margin	93	91	199	216
Intersegment	1	2	2	3
External Adjusted Gross Margin	94	93	201	219
Assets
Total Assets	4,643		4,643		4,178
Asia Generation [Member]
Revenue
Total Revenue	162	179	277	355
Intersegment	0	0	0	0
External Revenue	162	179	277	355
Adjusted Gross Margin
Adjusted Gross Margin	53	84	98	153
Intersegment	0	1	1	2
External Adjusted Gross Margin	53	85	99	155
Assets
Total Assets	1,702		1,702		1,762
Segment Discontinued Operations [Member]
Assets
Total Assets	226		226		258
Corporate Other And Other Eliminations [Member]
Revenue
Total Revenue	12	(14)	65	(19)
Intersegment	267	256	519	511
External Revenue	279	242	584	492
Adjusted Gross Margin
Adjusted Gross Margin	(14)	(2)	25	7
Intersegment	(6)	(10)	(18)	(20)
External Adjusted Gross Margin	(20)	(12)	7	(13)
Assets
Total Assets	$ 7,551		$ 7,551		$ 6,039