Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 installment	Dec. 31, 2012	Dec. 31, 2013 Brazil Tariff Estimated Rate Change Liability		Jul. 04, 2013 Brazil Tariff Estimated Rate Change Liability	Dec. 31, 2012 Brazil Tariff Estimated Rate Change Liability		Dec. 31, 2013 Efficiency Program Costs		Dec. 31, 2012 Efficiency Program Costs		Dec. 31, 2013 Brazil Regulatory Asset Base Adjustment		Dec. 31, 2012 Brazil Regulatory Asset Base Adjustment		Dec. 31, 2013 Brazil Tariff Recoveries Energy Purchases Liability		Dec. 31, 2012 Brazil Tariff Recoveries Energy Purchases Liability		Dec. 31, 2013 Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Liability		Dec. 31, 2012 Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Liability		Dec. 31, 2013 Asset Retirement Obligation Costs		Dec. 31, 2012 Asset Retirement Obligation Costs		Dec. 31, 2013 Brazil Special Obligations		Dec. 31, 2012 Brazil Special Obligations		Dec. 31, 2013 Other Regulatory Liabilities		Dec. 31, 2012 Other Regulatory Liabilities		Dec. 31, 2013 Brazil Tariff Recoveries Energy Purchases Asset		Dec. 31, 2012 Brazil Tariff Recoveries Energy Purchases Asset		Dec. 31, 2013 Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Asset		Dec. 31, 2012 Brazil Tariff Recoveries Transmission Costs Regulatory Fees And Other Asset		Dec. 31, 2013 El Salvador Tariff Recoveries		Dec. 31, 2012 El Salvador Tariff Recoveries		Dec. 31, 2013 Pension Costs		Dec. 31, 2012 Pension Costs		Dec. 31, 2013 Income Taxes Recoverable From Customers		Dec. 31, 2012 Income Taxes Recoverable From Customers		Dec. 31, 2013 Other Regulatory Assets		Dec. 31, 2012 Other Regulatory Assets		Dec. 31, 2013 Deferred Midwest Independent Service Operator Costs		Dec. 31, 2012 Deferred Midwest Independent Service Operator Costs
Schedule of Regulatory Assets and Liabilities [Line Items]
Total Current Regulatory Assets	$ 282	$ 408																																		$ 87	[1]	$ 189	[1]	$ 52	[1]	$ 78	[1]	$ 108	[2]	$ 115	[2]									$ 35	[3]	$ 26	[3]
Total Non Current Regulatory Assets	636	871																																		62	[1]	97	[1]	4	[1]	59	[1]					261	[4],[5]	430	[4],[5]	72	[4],[6]	81	[4],[6]	139	[3]	115	[3]	98	[7]	89	[7]
Total Regulatory Assets	918	1,279
Total Current Regulatory Liabilities	461	388	245	[8]		89	[8]	25	[9]	32	[9]	34	[10]	0	[10]	48	[1]	171	[1]	69	[1]	55	[1]									40	[11]	41	[11]
Total Non Current Regulatory Liabilities	1,592	1,702	82	[8]		445	[8]	10	[9]	17	[9]	235	[10]	0	[10]	16	[1]	46	[1]	42	[1]	42	[1]	696	[12]	672	[12]	502	[13]	463	[13]	9	[11]	17	[11]
Total Regulatory Liabilities	2,053	2,090
Period of annual tariff adjustment	12 months
Number of installments through which the Brazil tariff recoveries are made	24
Other current regulatory assets that did not earn a rate of return																																																								13		19
Other noncurrent regulatory assets that did not earn a rate of return																																																								$ 71		$ 60
Tariff adjustment, percentage amortized					67.55%
Tariff adjustment, percentage amortized in next tariff adjustment					32.45%

[1] Recoverable or refundable per National Electric Energy Agency (“ANEEL”) regulations through the Annual Tariff Adjustment (“IRT”). These costs are generally non-controllable costs and primarily consist of purchased electricity, energy transmission costs and sector costs that are considered volatile. These costs are passed through for a period of 12 months as part of the annual tariff adjustment. Any remaining balance is considered in the following annual tariff adjustment, being a total of 24 months to recover or refund the costs.

[2] Deferred fuel costs incurred by our El Salvador subsidiaries associated with purchase of energy from the El Salvador spot market and the power generation plants. In El Salvador, the deferred fuel adjustment represents the variance between the actual fuel costs and the fuel costs recovered in the tariffs. The variance is recovered quarterly at the tariff reset period.

[3] Includes assets with and without a rate of return. Other current regulatory assets that did not earn a rate of return were $13 million and $19 million, as of December 31, 2013 and 2012, respectively. Other noncurrent regulatory assets that did not earn a rate of return were $71 million and $60 million, as of December 31, 2013 and 2012, respectively. Other current and noncurrent regulatory assets primarily consist of:▪Unamortized losses on long-term debt reacquired or redeemed in prior periods at IPL and DPL, which are amortized over the lives of the original issues in accordance with the FERC and PUCO rules.▪Unamortized carrying charges and certain other costs related to Petersburg unit 4 at IPL.▪Deferred storm costs incurred primarily in 2008 to repair storm damage at DPL, which have been deferred until such time that DPL seeks recovery in a future rate proceeding.▪Additional Regulatory Asset Base (RAB) from a favorable decision on tariff reset (administrative appeal) at Eletropaulo.

[4] Past expenditures on which the Company does not earn a rate of return.

[5] The regulatory accounting standards allow the defined pension and postretirement benefit obligation to be recorded as a regulatory asset equal to the previously unrecognized actuarial gains and losses and prior service costs that are expected to be recovered through future rates. Pension expense is recognized based on the plan’s actuarially determined pension liability. Recovery of costs is probable, but not yet determined. Pension contributions made by our Brazilian subsidiaries are not included in regulatory assets as those contributions are not covered by the established tariff in Brazil.

[6] Probability of recovery through future rates, based upon established regulatory practices, which permit the recovery of current taxes. This amount is expected to be recovered, without interest, over the period as book-tax temporary differences reverse and become current taxes.

[7] Transmission service costs and other administrative costs from IPL’s participation in the Midwest ISO market, which are recoverable but do not earn a rate of return. Recovery of costs is probable, but the timing is not yet determined.

[8] In July 2012, the Brazilian energy regulator (the “Regulator”) approved the periodic review and reset of a component of Eletropaulo’s regulated tariff, which determines the margin to be earned by Eletropaulo. The review and reset of this tariff component is retroactive to July 2011 and will be applied to customers’ invoices from July 2012 to June 2015. From July 2011 through June 2012, Eletropaulo invoiced customers under the then existing tariff rate, as required by the Regulator. As the new tariff rate is lower than the pre-existing tariff rate, Eletropaulo is required to reduce customer tariffs for this difference over the next year. Accordingly, from July 2011 through June 2012, Eletropaulo recognized a regulatory liability for such estimated future refunds, which was subsequently adjusted as of June 30, 2012 upon the finalization of the new tariff with the Regulator. The refund to customers was considered in the 2013 tariff adjustment, which contemplates an amortization of 67.55% as from July 4, 2013. The remaining balance, representing 32.45%, will be considered in the next annual tariff adjustment. As of December 31, 2013, Eletropaulo had recorded a current and noncurrent regulatory liability of $245 million and $82 million, respectively.

[9] Amounts received for costs expected to be incurred to improve the efficiency of our plants in Brazil as part of the IRT.

[10] Represents adjustments to the regulatory asset base resulting from an administrative ruling in December 2013 which compelled Eletropaulo to refund customers beginning in July 2014.

[11] Other current and noncurrent regulatory liabilities primarily consist of liabilities owed to electricity generators due to variance in energy prices during rationing periods (“Free Energy”). Our Brazilian subsidiaries are authorized to recover or refund this cost associated with monthly energy price variances between the wholesale energy market prices owed to the power generation plants producing Free Energy and the capped price reimbursed by the local distribution companies which are passed through to the final customers through energy tariffs. The balance excludes asset retirement obligations that were reclassified out of Other.

[12] Obligations for removal costs which do not have an associated legal retirement obligation as defined by the accounting standards on asset retirement obligations.

[13] Obligations established by ANEEL in Brazil associated with electric utility concessions and represent amounts received from customers or donations not subject to return. These donations are allocated to support energy network expansion and to improve utility operations to meet customers’ needs. The term of the obligation is established by ANEEL. Settlement shall occur when the concession ends.