Contingencies and Commitments (Details)	3 Months Ended			3 Months Ended						6 Months Ended		12 Months Ended
	Sep. 30, 2011 USD ($) integer	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Sep. 30, 2011 Guarantees USD ($)	Sep. 30, 2011 Letters of credit under secured credit facility USD ($)	Sep. 30, 2011 Cash Collateralized Letters Of Credit [Member] USD ($)	Sep. 30, 2011 Eletropaulo [Member] USD ($)	Sep. 30, 2011 Eletropaulo [Member] BRL	Sep. 30, 2011 CESCO [Member] USD ($)	Jun. 30, 2009 Cartagena Affiliate [Member] USD ($)	Jun. 30, 2009 Cartagena Affiliate [Member] EUR (€)	Dec. 31, 2008 Cartagena Affiliate [Member] USD ($)	Dec. 31, 2008 Cartagena Affiliate [Member] EUR (€)	Dec. 31, 2007 Cartagena Affiliate [Member] USD ($)	Dec. 31, 2007 Cartagena Affiliate [Member] EUR (€)	Sep. 30, 2011 Cartagena Affiliate [Member] USD ($)	Sep. 30, 2011 Cartagena Affiliate [Member] EUR (€)	Sep. 30, 2011 UKHPP [Member] USD ($)	Sep. 30, 2011 UKHPP [Member] KZT	Sep. 30, 2011 Maritza [Member] USD ($)	Sep. 30, 2011 Maritza [Member] EUR (€)	Sep. 30, 2011 Shulbinsk [Member] USD ($)	Sep. 30, 2011 Shulbinsk [Member] KZT
Environmental Contingencies Disclosure [Abstract]
Liability recorded for projected environmental remediation costs	$ 22,000,000
Number Of Countries In Which Entity Operates	27
Estimated Annual Cost Of Environmental Compliance		15,000,000
Guarantees Letters Of Credit [Abstract]
The range of expiration dates of guarantees made by the Parent Company	less than one year to more than 15 years
Obligations made by the Parent Company associated with non-recourse debt	26,000,000
Contingent Contractual Obligations [Line Items]
Amount	629,000,000			357,000,000	12,000,000	260,000,000
Number of Agreements	47			23	11	13
Maximum Exposure Range for Each Agreement				<$1 - $53	<$1 - $7	<$1 - $223
Commitments to invest in subsidiaries, excluding letters of credit	16,000,000
Commitment to purchase DPL	3,500,000,000
Litigation Contingency Disclosure [Abstract]
Aggregate reserves for claims deemed both probable and reasonably estimable	372,000,000		448,000,000
Loss Contingency Range Of Possible Loss Maximum	1,200,000,000
Litigation Details [Line Items]
Litigation Collection Suit Alleged Amount							656,000,000	1,200,000,000
Arbitration Alleged Damages Amount									189,000,000
Litigation Alleged Fines																		1,000,000	120,000,000
Litigation Disgorge Of Profits																		3,000,000	440,000,000
Litigation Additional Damages																		8,000,000	1,200,000,000			9,000,000	1,300,000,000
Litigation Pollution Liability Amount							415,000,000	760,000,000
Litigation Notified Invoice Amount																27,000,000	20,000,000
Litigation Invoiced Amount										7,000,000	5,000,000	27,000,000	19,907,248	712,000	523,548
Litigation Allowances Paid To Date																34,000,000	25,000,000
Amount Demanded Under Performance Bond																				211,000,000	155,000,000
Damages Sought By Counterparty																				$ 326,000,000	€ 240,000,000