Supplemental Financial Information - Narrative (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Supplemental Financial Information Tables [Line Items]
Smart Grid Grant Project Capital Expenditures		$ 68
Smart Grid Grant Reimbursements		64
PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Smart Grid Grant Project Capital Expenditures	2	22
Smart Grid Grant Reimbursements	5	30
Financing Receivable, Net	19
Financing Receivable, Allowance for Credit Losses	19	18
Baltimore Gas and Electric Company [Member]
Supplemental Financial Information Tables [Line Items]
Smart Grid Grant Project Capital Expenditures		46
Smart Grid Grant Reimbursements		34
Low To Medium Risk [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	1	1
Risk Level, Medium [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	4	4
Risk Level, High [Member] | PECO Energy Co [Member]
Supplemental Financial Information Tables [Line Items]
Financing Receivable, Net	$ 14	$ 13