Consolidated Statements Of Cash Flows (USD $) In Millions	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Potomac Electric Power Co [Member]	Sep. 30, 2010 Potomac Electric Power Co [Member]	Sep. 30, 2011 Delmarva Power & Light Co/De [Member]	Sep. 30, 2010 Delmarva Power & Light Co/De [Member]	Sep. 30, 2011 Atlantic City Electric Co [Member]	Sep. 30, 2010 Atlantic City Electric Co [Member]
OPERATING ACTIVITIES
Net income (loss)	$ 238	$ (1)	$ 88	$ 77	$ 56	$ 29	$ 41	$ 54
(Income) loss from discontinued operations	(1)	126
Adjustments to reconcile net income (loss) to net cash from operating activities:
Depreciation and amortization	325	286	128	121	66	62	107	81
Non-cash rents from cross-border energy lease investments	(35)	(41)
Gain on early termination of finance leases held in trust	(39)
Effects of Pepco divestiture-related claims		11		11
Deferred income taxes	165	258	58	50	81	53	39	15
Losses on treasury rate locks reclassified into income	1	18
Other	(13)	(16)
Changes in:
Accounts receivable	86	(39)	5	(40)	39	3	(12)	(75)
Inventories	(20)	(16)			(6)	(2)	(7)
Prepaid expenses	(14)	(8)
Regulatory assets and liabilities, net	(108)	(103)	(16)	(25)	(34)	(8)	(58)	(70)
Accounts payable and accrued liabilities	(106)	11	(21)	12	(31)	(3)	(2)	(25)
Pension contributions	(110)	(100)	(40)		(40)		(30)
Prepaid New Jersey sales and excise tax							(49)	(45)
Pension benefit obligation, excluding contributions	39	50
Cash collateral related to derivative activities	5	(23)
Taxes accrued	(14)	(98)	92	60	(23)	(22)	73	64
Interest accrued	34	11
Other assets and liabilities	54	50	36	27	22	33	20	11
Conectiv Energy net assets held for sale	44	184
Net Cash From Operating Activities	531	560	330	293	130	145	122	10
INVESTING ACTIVITIES
Investment in property, plant and equipment	(639)	(551)	(361)	(225)	(146)	(191)	(96)	(110)
Department of Energy capital reimbursement awards received	27	3	24	3			3
Proceeds from sale of Conectiv Energy wholesale power generation business		1,635
Proceeds from early termination of finance leases held in trust	161
Changes in restricted cash equivalents	(10)	(2)
Net other investing activities	(10)	2	(8)			3	(11)	(3)
Investment in property, plant and equipment associated with Conectiv Energy assets held for sale		(138)
Net Cash (Used By) From Investing Activities	(471)	949	(345)	(222)	(146)	(188)	(104)	(113)
FINANCING ACTIVITIES
Dividends paid on common stock	(183)	(181)		(95)	(50)	(23)
Common stock issued for the Dividend Reinvestment Plan and employee-related compensation	36	36
Capital contribution from Parent							60	43
Redemption of preferred stock of subsidiaries	(6)						(6)
Issuances of long-term debt	235	102			35	78	200	23
Reacquisition of long-term debt	(60)	(1,466)		(16)	(35)	(31)	(25)	(25)
(Repayments) issuances of short-term debt, net	11	10				3	(158)	63
Cost of issuances	(10)	(6)
Net other financing activities	(1)	4	(3)	4	9	(5)	(2)
Net financing activities associated with Conectiv Energy assets held for sale		(10)
Net Cash From (Used By) Financing Activities	22	(1,511)	(3)	(107)	(41)	22	69	104
Net Increase (Decrease) in Cash and Cash Equivalents	82	(2)	(18)	(36)	(57)	(21)	87	1
Cash and Cash Equivalents of discontinued operations		(16)
Cash and Cash Equivalents at Beginning of Period	20		88	213	69	26	4	7
Cash and Cash Equivalents at Beginning of Period	21	46
CASH AND CASH EQUIVALENTS AT END OF PERIOD	103	28	70	177	12	5	91	8
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash received for income taxes, net		$ 14	$ 108	$ 25	$ 24	$ 5	$ 51	$ 2