Segments (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Revenue
Total Revenue	$ 4,381	$ 3,990	$ 13,117	$ 11,777
Intersegment	0	0	0	0
External Revenue	4,381	3,990	13,117	11,777
Reconciliation To Income From Continuing Operations Before Taxes
Depreciation and amortization	313	271	909	802
Interest expense	(432)	(381)	(1,178)	(1,151)
Interest income	103	96	293	304
Other expense	(76)	(23)	(131)	(83)
Other income	58	17	108	94
Gain on sale of investments	0	0	7	0
Goodwill impairment	(17)	(18)	(17)	(18)
Asset impairment expense	(163)	(296)	(196)	(297)
Foreign currency transaction (losses) gains on net monetary position	(92)	103	(21)	(19)
Other non-operating expense	(82)	(2)	(82)	(7)
Income from continuing operations before taxes and equity in earnings of affiliates	228	365	1,519	1,445
Assets
Total Assets	40,883		40,883		40,511
Latin America Generation [Member]
Revenue
Total Revenue	1,302	1,111	3,810	3,178
Intersegment	(328)	(267)	(842)	(778)
External Revenue	974	844	2,968	2,400
Adjusted Gross Margin
Adjusted Gross Margin	505	436	1,493	1,296
Intersegment	(313)	(262)	(800)	(766)
External Adjusted Gross Margin	192	174	693	530
Assets
Total Assets	10,545		10,545		10,373
Latin America Utilities [Member]
Revenue
Total Revenue	1,930	1,757	5,774	5,236
Intersegment	0	0	0	0
External Revenue	1,930	1,757	5,774	5,236
Adjusted Gross Margin
Adjusted Gross Margin	378	306	1,035	888
Intersegment	322	267	820	778
External Adjusted Gross Margin	700	573	1,855	1,666
Assets
Total Assets	8,938		8,938		9,872
North America Generation [Member]
Revenue
Total Revenue	372	413	1,116	1,173
Intersegment	0	0	(4)	0
External Revenue	372	413	1,112	1,173
Adjusted Gross Margin
Adjusted Gross Margin	145	146	402	406
Intersegment	3	5	6	12
External Adjusted Gross Margin	148	151	408	418
Assets
Total Assets	4,403		4,403		4,681
North America Utilities [Member]
Revenue
Total Revenue	321	306	890	869
Intersegment	0	0	0	0
External Revenue	321	306	890	869
Adjusted Gross Margin
Adjusted Gross Margin	113	118	292	324
Intersegment	0	0	1	1
External Adjusted Gross Margin	113	118	293	325
Assets
Total Assets	3,218		3,218		3,139
Europe Generation [Member]
Revenue
Total Revenue	397	282	1,125	864
Intersegment	0	0	(1)	0
External Revenue	397	282	1,124	864
Adjusted Gross Margin
Adjusted Gross Margin	128	71	327	287
Intersegment	2	2	4	5
External Adjusted Gross Margin	130	73	331	292
Assets
Total Assets	4,264		4,264		4,178
Asia Generation [Member]
Revenue
Total Revenue	172	136	449	491
Intersegment	0	0	0	0
External Revenue	172	136	449	491
Adjusted Gross Margin
Adjusted Gross Margin	35	51	133	204
Intersegment	0	1	1	3
External Adjusted Gross Margin	35	52	134	207
Assets
Total Assets	1,725		1,725		1,762
Segment Discontinued Operations [Member]
Assets
Total Assets	407		407		468
Corporate Other And Other Eliminations [Member]
Revenue
Total Revenue	(113)	(15)	(47)	(34)
Intersegment	328	267	847	778
External Revenue	215	252	800	744
Adjusted Gross Margin
Adjusted Gross Margin	(62)	12	(37)	19
Intersegment	(14)	(13)	(32)	(33)
External Adjusted Gross Margin	(76)	(1)	(69)	(14)
Assets
Total Assets	$ 7,383		$ 7,383		$ 6,038