Fair Value Disclosures (Summary Of Primary Unobservable Inputs Used To Determine Fair Value Of Level 3 Instruments And Range Of Values That For Those Inputs) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Derivative
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	5,358
Atlantic City Electric Co [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	1,357
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	500
Significant Unobservable Inputs (Level 3) [Member] | Atlantic City Electric Co [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	132
Significant Unobservable Inputs (Level 3) [Member] | Natural Gas Options [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	(4)
Significant Unobservable Inputs (Level 3) [Member] | Natural Gas Options [Member] | Minimum [Member] | Derivative [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Volatility factor, range	1.57
Significant Unobservable Inputs (Level 3) [Member] | Natural Gas Options [Member] | Maximum [Member] | Derivative [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Volatility factor, range	2.00
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	(3)
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member] | Derivative [Member] | Atlantic City Electric Co [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value of financial instrument	(3)
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member] | Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discounted cash flow, Discount rate	500.00%
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member] | Minimum [Member] | Derivative [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discounted cash flow, Discount rate	5.00%
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member] | Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discounted cash flow, Discount rate	900.00%
Significant Unobservable Inputs (Level 3) [Member] | Capacity Contracts, Net [Member] | Maximum [Member] | Derivative [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Discounted cash flow, Discount rate	9.00%