Segment Information (Details) (USD $)	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Depreciation and amortization	$ 105,000,000		$ 93,000,000		$ 210,000,000		$ 182,000,000
Reversal of valuation allowances on tax deferred tax assets			8,000,000				8,000,000
Segment reporting information deferred tax asset writeoff related to the Medicare Part D							4,000,000
Pre-tax gain from the early termination of finance leases					39,000,000
State tax benefit							8,000,000
Power Delivery [Member]
Operating Revenue	1,093,000,000		1,149,000,000		2,342,000,000		2,411,000,000
Operating Expenses	957,000,000	[1]	996,000,000	[2]	2,088,000,000	[3]	2,165,000,000	[4]
Operating Income	136,000,000		153,000,000		254,000,000		246,000,000
Interest Income			1,000,000				1,000,000
Interest Expense	52,000,000		53,000,000		102,000,000		104,000,000
Other Income (Expenses)	8,000,000		5,000,000		16,000,000		9,000,000
Income Tax Expense (Benefit)	20,000,000	[5]	41,000,000		49,000,000	[5]	67,000,000	[6]
Net Income (Loss) from Continuing Operations	72,000,000		65,000,000		119,000,000		85,000,000
Total Assets	10,803,000,000		10,429,000,000		10,803,000,000		10,429,000,000
Construction Expenditures	204,000,000		194,000,000		364,000,000		345,000,000
Goodwill	1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000
Depreciation and amortization	97,000,000		85,000,000		194,000,000		167,000,000
After-tax state income tax benefit			8,000,000
Accrued interest income on uncertain and effectively settled income tax positions							8,000,000
Tax benefits related to federal tax liabilities	14,000,000				14,000,000
Reversal of valuation allowances on tax deferred tax assets	22,000,000				22,000,000
Pepco Energy Services [Member]
Operating Revenue	308,000,000		476,000,000		681,000,000		1,023,000,000
Operating Expenses	295,000,000	[1]	453,000,000	[2]	652,000,000	[3]	975,000,000	[4]
Operating Income	13,000,000		23,000,000		29,000,000		48,000,000
Interest Expense	1,000,000		5,000,000		2,000,000		10,000,000
Other Income (Expenses)	1,000,000				2,000,000		1,000,000
Income Tax Expense (Benefit)	5,000,000	[5]	8,000,000		11,000,000	[5]	16,000,000
Net Income (Loss) from Continuing Operations	8,000,000		10,000,000		18,000,000		23,000,000
Total Assets	615,000,000		653,000,000		615,000,000		653,000,000
Construction Expenditures	6,000,000				7,000,000		1,000,000
Depreciation and amortization	5,000,000		5,000,000		9,000,000		9,000,000
Other Non-Regulated [Member]
Operating Revenue	14,000,000		13,000,000		28,000,000		26,000,000
Operating Expenses	(38,000,000)	[1],[7]	2,000,000	[2]	(36,000,000)	[3],[7]	3,000,000	[4]
Operating Income	52,000,000		11,000,000		64,000,000		23,000,000
Interest Income	1,000,000		1,000,000		2,000,000		2,000,000
Interest Expense	4,000,000		3,000,000		7,000,000		7,000,000
Other Income (Expenses)					(1,000,000)		(1,000,000)
Preferred Stock Dividends					1,000,000		1,000,000
Income Tax Expense (Benefit)	30,000,000	[5]	3,000,000		32,000,000	[5]	6,000,000
Net Income (Loss) from Continuing Operations	19,000,000	[7]	6,000,000		25,000,000	[7]	10,000,000
Total Assets	1,461,000,000		1,462,000,000		1,461,000,000		1,462,000,000
Depreciation and amortization	1,000,000		1,000,000		1,000,000		1,000,000
Corporate And Other [Member]
Operating Revenue	(6,000,000)	[8]	(2,000,000)	[9]	(8,000,000)	[10]	(5,000,000)	[11]
Operating Expenses	(7,000,000)	[1],[8]	(8,000,000)	[2],[9]	(12,000,000)	[10],[3]	(12,000,000)	[11],[4]
Operating Income	1,000,000	[8]	6,000,000	[9]	4,000,000	[10]	7,000,000	[11]
Interest Income	(1,000,000)	[8]	(2,000,000)	[9]	(2,000,000)	[10]	(3,000,000)	[11]
Interest Expense	6,000,000	[8]	28,000,000	[9]	14,000,000	[10]	51,000,000	[11]
Other Income (Expenses)	1,000,000	[8]			2,000,000	[10]	1,000,000	[11]
Preferred Stock Dividends					(1,000,000)	[10]	(1,000,000)	[11]
Income Tax Expense (Benefit)	(1,000,000)	[5],[8]	(19,000,000)	[12],[9]	(4,000,000)	[10],[5]	(31,000,000)	[11],[13]
Net Income (Loss) from Continuing Operations	(4,000,000)	[8]	(5,000,000)	[9]	(5,000,000)	[10]	(14,000,000)	[11]
Total Assets	1,354,000,000	[10],[8]	1,442,000,000	[11],[9]	1,354,000,000	[10],[8]	1,442,000,000	[11],[9]
Construction Expenditures	6,000,000	[8]	12,000,000	[9]	16,000,000	[10]	18,000,000	[11]
Depreciation and amortization	2,000,000		2,000,000		6,000,000		5,000,000
Operating Revenue	(6,000,000)		(2,000,000)		(8,000,000)		(5,000,000)
Operating Expense	(4,000,000)		(1,000,000)		(6,000,000)		(5,000,000)
Interest Income	(5,000,000)		(13,000,000)		(10,000,000)		25,000,000
Interest Expense	(5,000,000)		(13,000,000)		(9,000,000)		(25,000,000)
Preferred Stock Dividends					(1,000,000)		(1,000,000)
PHI Consolidated [Member]
Operating Revenue	1,409,000,000		1,636,000,000		3,043,000,000		3,455,000,000
Operating Expenses	1,207,000,000	[1]	1,443,000,000	[2]	2,692,000,000	[3]	3,131,000,000	[4]
Operating Income	202,000,000		193,000,000		351,000,000		324,000,000
Interest Expense	63,000,000		89,000,000		125,000,000		172,000,000
Other Income (Expenses)	10,000,000		5,000,000		19,000,000		10,000,000
Income Tax Expense (Benefit)	54,000,000	[5]	33,000,000		88,000,000	[5]	58,000,000
Net Income (Loss) from Continuing Operations	95,000,000		76,000,000		157,000,000		104,000,000
Total Assets	14,233,000,000		13,986,000,000		14,233,000,000		13,986,000,000
Construction Expenditures	$ 216,000,000		$ 206,000,000		$ 387,000,000		$ 364,000,000

[1] Includes depreciation and amortization of $105 million, consisting of $97 million for Power Delivery, $5 million for Pepco Energy Services, $1 million for Other Non-Regulated, and $2 million for Corporate and Other.

[2] Includes depreciation and amortization of $93 million, consisting of $85 million for Power Delivery, $5 million for Pepco Energy Services, $1 million for Other Non-Regulated and $2 million for Corporate and Other.

[3] Includes depreciation and amortization of $210 million, consisting of $194 million for Power Delivery, $9 million for Pepco Energy Services, $1 million for Other Non-Regulated, and $6 million for Corporate and Other.

[4] Includes depreciation and amortization of $182 million, consisting of $167 million for Power Delivery, $9 million for Pepco Energy Services, $1 million for Other Non-Regulated and $5 million for Corporate and Other.

[5] Includes tax benefits of $14 million for Power Delivery primarily associated with an interest benefit related to federal tax liabilities and a $22 million reversal of previously recognized tax benefits for Other Non-Regulated associated with the early termination of finance leases held in trust.

[6] Includes $8 million reversal of accrued interest income on uncertain and effectively settled state income tax positions.

[7] Includes $39 million pre-tax ($3 million after-tax) gain from the early termination of finance leases held in trust.

[8] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to the Power Delivery segment for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit the Power Delivery business. These expenditures are recorded as incurred in the Corporate and Other segment and are allocated to Power Delivery once the assets are placed in service. Additionally, Corporate and Other includes intercompany amounts of $(6) million for Operating Revenue, $(4) million for Operating Expense, $(5) million for Interest Income and $(5) million for Interest Expense.

[9] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to the Power Delivery segment for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit the Power Delivery business. These expenditures are recorded as incurred in the Corporate and Other segment and are allocated to Power Delivery once the assets are place in service. Additionally, Corporate and Other includes intercompany amounts of $(2) million for Operating Revenue, $(1) million for Operating Expense, $(13) million for Interest Income and $(13) million for Interest Expense.

[10] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to the Power Delivery segment for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit the Power Delivery business. These expenditures are recorded as incurred in the Corporate and Other segment and are allocated to Power Delivery once the assets are placed in service. Additionally, Corporate and Other includes intercompany amounts of $(8) million for Operating Revenue, $(6) million for Operating Expense, $(10) million for Interest Income, $(9) million for Interest Expense, and $(1) million for Preferred Stock Dividends.

[11] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to the Power Delivery segment for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit the Power Delivery business. These expenditures are recorded as incurred in the Corporate and Other segment and are allocated to Power Delivery once the assets are placed in service. Additionally, Corporate and Other includes intercompany amounts of $(5) million for Operating Revenue, $(5) million for Operating Expense, $(25) million for Interest Income, $(25) million for Interest Expense, and $(1) million for Preferred Stock Dividends.

[12] Includes $8 million state tax benefit from changed apportionment arising from the restructuring of certain PHI subsidiaries.

[13] Includes $8 million state tax benefit from changed apportionment arising from the restructuring of certain PHI subsidiaries and the release of $8 million of valuation allowances on deferred tax assets related to state net operating losses, partially offset by a charge of $4 million to write off a deferred tax asset related to the Medicare Part D subsidy.