Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Revenue
Total Revenue	$ 4,859	$ 4,637	$ 14,346	$ 13,751
Intersegment	(272)	(330)	(827)	(853)
External Revenue	4,587	4,307	13,519	12,898
Reconciliation To Income From Continuing Operations Before Taxes
Depreciation and amortization	327	303	1,019	879
Interest expense	(401)	(418)	(1,202)	(1,137)
Interest income	89	102	263	293
Other expense	(15)	(76)	(59)	(126)
Other income	7	57	40	107
Gain on sale of investments	30	0	214	7
Goodwill impairment	(1,850)	(17)	(1,850)	(17)
Asset impairment expense	(43)	(130)	(72)	(163)
Foreign currency transaction losses	(8)	(90)	(110)	(20)
Other non-operating expense	0	(82)	(50)	(82)
Income from continuing operations before taxes and equity in earnings of affiliates	(1,251)	266	(277)	1,575
Assets
Total Assets	41,356		41,356		45,346
Generation Latin America Other [Member]
Revenue
Total Revenue	1,036	984	3,024	2,984
Intersegment	(10)	(8)	(29)	(28)
External Revenue	1,026	976	2,995	2,956
Adjusted Gross Margin
Adjusted Gross Margin	301	258	820	852
Intersegment	5	(10)	15	(4)
External Adjusted Gross Margin	306	248	835	848
Assets
Total Assets	9,168		9,168		9,067
Generation Tiete [Member]
Segment Reporting Information [Line Items]
Generation Capacity (MW)	2,663		2,663
Revenue
Total Revenue	268	317	847	826
Intersegment	(260)	(320)	(790)	(813)
External Revenue	8	(3)	57	13
Adjusted Gross Margin
Adjusted Gross Margin	204	248	653	641
Intersegment	(260)	(320)	(790)	(813)
External Adjusted Gross Margin	(56)	(72)	(137)	(172)
Assets
Total Assets	1,486		1,486		1,645
Generation North America [Member]
Revenue
Total Revenue	359	334	1,004	1,007
Intersegment	0	0	0	(4)
External Revenue	359	334	1,004	1,003
Adjusted Gross Margin
Adjusted Gross Margin	133	119	355	335
Intersegment	2	3	8	6
External Adjusted Gross Margin	135	122	363	341
Assets
Total Assets	3,584		3,584		3,625
Generation Europe [Member]
Revenue
Total Revenue	245	397	928	1,125
Intersegment	0	0	(1)	(1)
External Revenue	245	397	927	1,124
Adjusted Gross Margin
Adjusted Gross Margin	98	128	419	327
Intersegment	2	2	(5)	4
External Adjusted Gross Margin	100	130	414	331
Assets
Total Assets	3,398		3,398		3,276
Generation Asia [Member]
Revenue
Total Revenue	191	172	553	449
Intersegment	0	0	0	0
External Revenue	191	172	553	449
Adjusted Gross Margin
Adjusted Gross Margin	66	35	188	133
Intersegment	0	0	1	1
External Adjusted Gross Margin	66	35	189	134
Assets
Total Assets	2,281		2,281		1,717
Utilities Latin America [Member]
Revenue
Total Revenue	1,667	1,898	4,847	5,682
Intersegment	0	0	0	0
External Revenue	1,667	1,898	4,847	5,682
Adjusted Gross Margin
Adjusted Gross Margin	147	381	358	1,041
Intersegment	261	322	796	820
External Adjusted Gross Margin	408	703	1,154	1,861
Assets
Total Assets	8,500		8,500		9,468
Utilities North America [Member]
Revenue
Total Revenue	796	321	2,206	890
Intersegment	0	0	0	0
External Revenue	796	321	2,206	890
Adjusted Gross Margin
Adjusted Gross Margin	262	112	668	291
Intersegment	0	0	1	1
External Adjusted Gross Margin	262	112	669	292
Assets
Total Assets	7,430		7,430		9,397
Segment Discontinued Operations [Member]
Assets
Total Assets	24		24		1,576
Corporate Other And Other Eliminations [Member]
Revenue
Total Revenue	297	214	937	788
Intersegment	(2)	(2)	(7)	(7)
External Revenue	295	212	930	781
Adjusted Gross Margin
Adjusted Gross Margin	44	(68)	105	(34)
Intersegment	2	13	(24)	(9)
External Adjusted Gross Margin	46	(55)	81	(43)
Assets
Total Assets	$ 5,485		$ 5,485		$ 5,575