Label	Element	Value
Pepco Holdings LLC [Member] | Predecessor [Member]
Proceeds from Stock Plans	us-gaap_ProceedsFromStockPlans	$ 2,000,000
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	290,000,000
Repayments of Short-term Debt, Maturing in More than Three Months	us-gaap_RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths	0
Impairment of Long-Lived Assets Held-for-use	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse	0
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	19,000,000
Increase (Decrease) in Due to Affiliates, Current	us-gaap_IncreaseDecreaseInDueToAffiliatesCurrent	0
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	18,000,000
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(121,000,000)
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	46,000,000
Net Cash Provided by (Used in) Operating Activities	us-gaap_NetCashProvidedByUsedInOperatingActivities	264,000,000
Net Cash Provided by (Used in) Financing Activities	us-gaap_NetCashProvidedByUsedInFinancingActivities	372,000,000
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	(4,000,000)
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	(28,000,000)
Proceeds from Contributions from Parent	us-gaap_ProceedsFromContributionsFromParent	0
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	500,000,000
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	11,000,000
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	42,000,000
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	5,000,000
Payments of Distributions to Affiliates	us-gaap_PaymentsOfDistributionsToAffiliates	0
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	2,000,000
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	68,000,000
Increase (Decrease) in Other Operating Assets and Liabilities, Net	us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet	(8,000,000)
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	0
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	0
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	12,000,000
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	(346,000,000)
Pepco Holdings LLC [Member] | Successor [Member]
Proceeds from Stock Plans	us-gaap_ProceedsFromStockPlans	0
Cash and Cash Equivalents, Period Increase (Decrease)	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease	(112,000,000)
Repayments of Short-term Debt, Maturing in More than Three Months	us-gaap_RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths	300,000,000
Deferred Income Taxes and Tax Credits	us-gaap_DeferredIncomeTaxesAndTaxCredits	295,000,000
Increase (Decrease) in Due to Affiliates, Current	us-gaap_IncreaseDecreaseInDueToAffiliatesCurrent	(6,000,000)
Unrealized Gain (Loss) on Derivatives	us-gaap_UnrealizedGainLossOnDerivatives	0
Proceeds from (Repayments of) Short-term Debt, Maturing in Three Months or Less	us-gaap_ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess	(515,000,000)
Other Noncash Income (Expense)	us-gaap_OtherNoncashIncomeExpense	515,000,000
Net Cash Provided by (Used in) Operating Activities	us-gaap_NetCashProvidedByUsedInOperatingActivities	888,000,000
Net Cash Provided by (Used in) Financing Activities	us-gaap_NetCashProvidedByUsedInFinancingActivities	(7,000,000)
Increase (Decrease) in Inventories	us-gaap_IncreaseDecreaseInInventories	3,000,000
Increase (Decrease) in Receivables	us-gaap_IncreaseDecreaseInReceivables	(21,000,000)
Proceeds from Short-term Debt, Maturing in More than Three Months	us-gaap_ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths	0
Repayments of Long-term Debt	us-gaap_RepaymentsOfLongTermDebt	338,000,000
Increase (Decrease) in Accounts Payable and Accrued Liabilities	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	19,000,000
Payments for (Proceeds from) Other Investing Activities	us-gaap_PaymentsForProceedsFromOtherInvestingActivities	(15,000,000)
Proceeds from (Payments for) Other Financing Activities	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities	(5,000,000)
Payments to Acquire Marketable Securities	us-gaap_PaymentsToAcquireMarketableSecurities	0
Increase (Decrease) in Other Operating Assets and Liabilities, Net	us-gaap_IncreaseDecreaseInOtherOperatingCapitalNet	(311,000,000)
Proceeds from Issuance of Long-term Debt	us-gaap_ProceedsFromIssuanceOfLongTermDebt	179,000,000
Change Receivables Payables From Affiliates	exc_ChangeReceivablesPayablesFromAffiliates	42,000,000
Increase (Decrease) in Income Taxes Payable	us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayable	(22,000,000)
Net Cash Provided by (Used in) Investing Activities	us-gaap_NetCashProvidedByUsedInInvestingActivities	$ (993,000,000)