Consolidated Statements Of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES
Net Income	$ 257	$ 32	$ 235
Loss (income) from discontinued operations, net of income taxes	3	107	(12)
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	426	393	349
Non-cash rents from cross-border energy lease investments	(55)	(55)	(54)
Gain on early termination of finance leases held in trust	(39)
Non-cash charge to reduce equity value of PHI's cross-border energy lease investments	7	2	3
Effects of Pepco divestiture-related claims		11	(40)
Changes in restricted cash equivalents related to Mirant settlement			102
Deferred income taxes	140	345	249
Net unrealized losses on Pepco Energy Services commodity derivatives	30	3	2
Losses on treasury rate locks reclassified into income	1	18	5
Other	(19)	(20)	(3)
Changes in:
Accounts receivable	135	(12)	136
Inventories	(6)	(2)	20
Prepaid expenses	(4)	7	(17)
Regulatory assets and liabilities, net	(148)	(154)	(221)
Accounts payable and accrued liabilities	(90)	73	(153)
Pension contributions	(110)	(100)	(300)
Pension benefit obligation, excluding contributions	53	68	95
Cash collateral related to derivative activities	9	13	24
Taxes accrued	11	(213)	76
Other assets and liabilities	43	49	7
Conectiv Energy net assets held for sale	42	248	103
Net Cash From Operating Activities	686	813	606
INVESTING ACTIVITIES
Investment in property, plant and equipment	(941)	(802)	(664)
Department of Energy capital reimbursement awards received	52	13
Proceeds from sale of Conectiv Energy wholesale power generation business		1,640
Proceeds from early termination of finance leases held in trust	161
Changes in restricted cash equivalents	(10)	(2)
Proceeds from sale of assets		3	4
Net other investing activities	(9)	4
Investment in property, plant and equipment associated with Conectiv Energy assets held for sale		(138)	(200)
Net Cash (Used By) From Investing Activities	(747)	718	(860)
FINANCING ACTIVITIES
Dividends paid on common stock	(244)	(241)	(238)
Common stock issued for the Dividend Reinvestment Plan and employee-related compensation	47	47	49
Redemption of preferred stock of subsidiaries	(6)
Issuances of long-term debt	235	383	110
Reacquisition of long-term debt	(70)	(1,726)	(83)
Issuances (repayments) of short-term debt, net	198	4	65
Cost of issuances	(10)	(7)	(4)
Net other financing activities	(1)	(6)	10
Net financing activities associated with Conectiv Energy assets held for sale		(10)	7
Net Cash (Used By) From Financing Activities	149	(1,556)	(84)
Net Increase (Decrease) in Cash and Cash Equivalents	88	(25)	(338)
Cash and Cash Equivalents of Discontinued Operations		(1)	(2)
Cash and Cash Equivalents at Beginning of Year	21	46	384
Cash and Cash Equivalents at Beginning of Year	20	44
CASH AND CASH EQUIVALENTS AT END OF YEAR	109	20	44
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest, net	240	310	353
Cash (received) paid for income taxes	4	(13)	(76)
Potomac Electric Power Co [Member]
OPERATING ACTIVITIES
Net Income	99	108	106
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	171	162	145
Effects of Pepco divestiture-related claims		11	(40)
Changes in restricted cash equivalents related to Mirant settlement			102
Deferred income taxes	73	74	122
Investment tax credit amortization	(2)	(2)	(2)
Changes in:
Accounts receivable	33	(15)	23
Inventories	(6)	(1)	2
Prepaid expenses	1	3	(9)
Regulatory assets and liabilities, net	(43)	(34)	(66)
Accounts payable and accrued liabilities	(27)	15	4
Pension contributions	(40)		(170)
Pension benefit obligation, excluding contributions	24	22	17
Taxes accrued	73	6	77
Interest accrued	(1)	(1)	(1)
Other assets and liabilities	2	11	21
Net Cash From Operating Activities	357	359	331
INVESTING ACTIVITIES
Investment in property, plant and equipment	(521)	(359)	(288)
Department of Energy capital reimbursement awards received	48	11
Changes in restricted cash equivalents		1	(1)
Net other investing activities	(7)	3	(1)
Net Cash (Used By) From Investing Activities	(480)	(344)	(290)
FINANCING ACTIVITIES
Dividends paid on common stock	(25)	(115)
Capital contribution from Parent			94
Issuances of long-term debt			110
Reacquisition of long-term debt		(16)	(50)
Issuances (repayments) of short-term debt, net	74		(125)
Net other financing activities	(2)	(9)	(3)
Net Cash (Used By) From Financing Activities	47	(140)	26
Net Increase (Decrease) in Cash and Cash Equivalents	(76)	(125)	67
Cash and Cash Equivalents at Beginning of Year	88	213	146
CASH AND CASH EQUIVALENTS AT END OF YEAR	12	88	213
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest, net	91	94	97
Cash (received) paid for income taxes	(108)	(20)	(126)
Delmarva Power & Light Co/De [Member]
OPERATING ACTIVITIES
Net Income	71	45	52
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	89	83	76
Deferred income taxes	57	74	60
Investment tax credit amortization	(1)	(1)	(1)
Changes in:
Accounts receivable	26	(21)	10
Inventories	(3)	(1)	12
Regulatory assets and liabilities, net	(32)	(12)	29
Accounts payable and accrued liabilities	(23)	31	(26)
Pension contributions	(40)		(10)
Pension benefit obligation, excluding contributions	17	18	37
Taxes accrued	14	11	(37)
Other assets and liabilities	3	(1)	11
Net Cash From Operating Activities	178	226	213
INVESTING ACTIVITIES
Investment in property, plant and equipment	(229)	(250)	(193)
Proceeds from sale of assets			1
Net other investing activities	(4)	2	1
Net Cash (Used By) From Investing Activities	(233)	(248)	(191)
FINANCING ACTIVITIES
Dividends paid on common stock	(60)	(23)	(28)
Capital contribution from Parent		11	32
Issuances of long-term debt	35	109
Reacquisition of long-term debt	(35)	(31)
Issuances (repayments) of short-term debt, net	47		(141)
Net other financing activities	4	(1)	3
Net Cash (Used By) From Financing Activities	(9)	65	(134)
Net Increase (Decrease) in Cash and Cash Equivalents	(64)	43	(112)
Cash and Cash Equivalents at Beginning of Year	69	26	138
CASH AND CASH EQUIVALENTS AT END OF YEAR	5	69	26
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest, net	43	40	41
Cash (received) paid for income taxes	(24)	(49)	(17)
Atlantic City Electric Co [Member]
OPERATING ACTIVITIES
Net Income	39	53	41
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	134	112	102
Deferred income taxes	42	49	53
Investment tax credit amortization	(1)	(1)	(1)
Changes in:
Accounts receivable	26	(35)	19
Inventories	(8)	(2)
Regulatory assets and liabilities, net	(74)	(107)	(183)
Accounts payable and accrued liabilities	(18)	(24)	43
Pension contributions	(30)		(60)
Taxes accrued	45	(10)	(6)
Other assets and liabilities	16	24	(16)
Net Cash From Operating Activities	171	59	(8)
INVESTING ACTIVITIES
Investment in property, plant and equipment	(138)	(156)	(141)
Department of Energy capital reimbursement awards received	4	2
Net other investing activities	(9)	(3)
Net Cash (Used By) From Investing Activities	(143)	(157)	(141)
FINANCING ACTIVITIES
Dividends paid on common stock		(35)	(64)
Capital contribution from Parent	60	43	129
Redemption of preferred stock of subsidiaries	(6)
Issuances of long-term debt	200	23
Reacquisition of long-term debt	(35)	(35)	(32)
Issuances (repayments) of short-term debt, net	(158)	98	60
Net other financing activities	(2)	1	(2)
Net Cash (Used By) From Financing Activities	59	95	91
Net Increase (Decrease) in Cash and Cash Equivalents	87	(3)	(58)
Cash and Cash Equivalents at Beginning of Year	4	7	65
CASH AND CASH EQUIVALENTS AT END OF YEAR	91	4	7
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest, net	64	61	65
Cash (received) paid for income taxes	$ (51)	$ 10	$ (42)