Derivative Instruments And Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2011

Dec. 31, 2010

Fair Value Of Derivative Instruments By Balance Sheet Location

As of December 31, 2011
Balance Sheet Caption	Derivatives Designated as Hedging Instruments(a)			Other Derivative Instruments(b)			Gross Derivative Instruments			Effects of Cash Collateral and Netting			Net Derivative Instruments
	(millions of dollars)
Derivative assets (current assets)	$	17		$	6		$	23		$	(18	)	$	5
Derivative assets (non-current assets)		—			1			1			(1	)		—
Total Derivative assets		17			7			24			(19	)		5
Derivative liabilities (current liabilities)		(55	)		(48	)		(103	)		77			(26	)
Derivative liabilities (non-current liabilities)		(11	)		(10	)		(21	)		15			(6	)
Total Derivative liabilities		(66	)		(58	)		(124	)		92			(32	)
Net Derivative (liability) asset	$	(49	)	$	(51	)	$	(100	)	$	73		$	(27	)

(a) Amounts included in Derivatives Designated as Hedging Instruments primarily consist of derivatives that were designated as cash flow hedges prior to Pepco Energy Services' election to discontinue cash flow hedge accounting for these derivatives.

(b) Amounts included in Other Derivative Instruments include gains or losses on derivatives that are not accounted for as cash flow hedges subsequent to Pepco Energy Services' election to discontinue cash flow hedge accounting.

	As of December 31, 2010
Balance Sheet Caption	Derivatives Designated as Hedging Instruments			Other Derivative Instruments			Gross Derivative Instruments			Effects of Cash Collateral and Netting			Net Derivative Instruments
	(millions of dollars)
Derivative assets (current assets)	$	40		$	43		$	83		$	(38	)	$	45
Derivative assets (non-current assets)		16			3			19			(19	)		—
Total Derivative assets		56			46			102			(57	)		45
Derivative liabilities (current liabilities)		(125	)		(63	)		(188	)		122			(66	)
Derivative liabilities (non-current liabilities)		(68	)		(10	)		(78	)		57			(21	)
Total Derivative liabilities		(193	)		(73	)		(266	)		179			(87	)
Net Derivative (liability) asset	$	(137	)	$	(27	)	$	(164	)	$	122		$	(42	)

Schedule Of Cash Collateral Offset Against Derivative Positions

	December 31, 2011		December 31, 2010
	(millions of dollars)
Cash collateral pledged to counterparties with the right to reclaim (a)	$	73	$	122

(a) Includes cash deposits on commodity brokerage accounts.

Activity Of Energy Commodity Contracts Designated As Cash Flow Hedges

	For the Year Ended December 31,
	2011		2010			2009
	(millions of dollars)
Amount of net pre-tax loss arising during the period included in accumulated other comprehensive loss	$	—	$	(100	)	$	(129	)
Amount of net pre-tax (gain) loss reclassified into income:
Effective portion:
Fuel and purchased energy		80		135			164
Ineffective portion: (a)
Revenue		1		—			2
Total net pre-tax (gain) loss reclassified into income		81		135			166
Net pre-tax gain (loss) on commodity derivatives included in other comprehensive loss	$	81	$	35		$	37

(a) Included in the above table is a loss of $1 million and $2 million for the years ended December 31, 2011 and 2009, respectively, which were reclassified from AOCL to income because the forecasted hedged transactions were deemed probable not to occur.

Outstanding Energy Commodity Contracts Employed As Cash Flow Hedges

	Quantities
Commodity	December 31, 2011		December 31, 2010
Forecasted Purchases Hedges
Natural gas (One Million British Thermal Units (MMBtu))		—		8,597,106
Electricity (Megawatt hours (MWh))		614,560		2,677,640
Electric capacity (MW-Days)		—		34,730
Forecasted Sales Hedges
Electricity (MWh)		614,560		2,517,200

Net Unrealized Derivative Gain (Loss) Deferred As A Regulatory Asset Or Liability

	For the Year Ended December 31,
	2011			2010			2009
	(millions of dollars)
Net unrealized losses arising during the period included in Regulatory assets	$	—		$	(9	)	$	(20	)
Net realized losses recognized in Fuel and purchased energy expense		(5	)		(13	)		(41	)

Cash Flow Hedges Included In Accumulated Other Comprehensive Loss

Contracts	As of December 31, 2011				Maximum Term
	Accumulated Other Comprehensive Loss After-tax		Portion Expected to be Reclassified to Income during the Next 12 Months
	(millions of dollars)
Energy commodity (a)	$	29	$	23		29 months
Interest rate		10		1		248 months
Total	$	39	$	24

(a) The unrealized derivative losses recorded in AOCL relate to forecasted natural gas and electricity physical purchases which are used to supply retail natural gas and electricity contracts that are in gain positions and subject to accrual accounting. Under accrual accounting, no asset is recorded on the balance sheet and the purchase cost is not recognized until the period of distribution.

Contracts	As of December 31, 2010				Maximum Term
	Accumulated Other Comprehensive Loss After-tax		Portion Expected to be Reclassified to Income during the Next 12 Months
	(millions of dollars)
Energy commodity (a)	$	78	$	48		41 months
Interest rate		11		1		260 months
Total	$	89	$	49

(a) The unrealized derivative losses recorded in AOCL relate to forecasted natural gas and electricity physical purchases which are used to supply retail natural gas and electricity contracts that are in gain positions and subject to accrual accounting. Under accrual accounting, no asset is recorded on the balance sheet and the purchase cost is not recognized until the period of distribution.

Pepco Energy Services [Member]

Outstanding Energy Commodity Contracts Employed As Cash Flow Hedges

	December 31, 2011				December 31, 2010
Commodity	Quantity		Net Position		Quantity		Net Position
Financial transmission rights (MWh)		267,480		Long		381,215		Long
Electric capacity (MW-Days)		12,920		Long		2,265		Long
Electricity (MWh)		788,280		Long		1,455,800		Long
Natural gas (MMBtu)		24,550,257		Long		45,889,486		Long

Schedule Of Derivative Gain (Loss) Amounts Recognized In Income

	For the Year Ended December 31,
	2011			2010			2009
	(millions of dollars)
Realized gains (losses)	$	—		$	2		$	(2	)
Unrealized mark-to-market losses		(30	)		(3	)		(2	)
Total net losses	$	(30	)	$	(1	)	$	(4	)

Delmarva Power & Light Co/De [Member]

Outstanding Energy Commodity Contracts Employed As Cash Flow Hedges

	Quantities
Commodity	December 31, 2011		December 31, 2010
Forecasted Purchases Hedges
Natural gas (MMBtu)		—		1,840,000

Net Unrealized Derivative Gain (Loss) Deferred As A Regulatory Asset Or Liability

	For the Year Ended December 31,
	2011			2010			2009
	(millions of dollars)
Net unrealized losses arising during the period included in Regulatory assets	$	(13	)	$	(20	)	$	(18	)
Net realized losses recognized in Fuel and purchased energy expense		(22	)		(26	)		(11	)

Net Outstanding Commodity Forward Contracts That Did Not Qualify For Hedge Accounting

	December 31, 2011				December 31, 2010
Commodity	Quantity		Net Position		Quantity		Net Position
Natural gas (MMBtu)		6,161,200		Long		8,236,500		Long