Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Dec. 31, 2011
Segment Reporting Information [Line Items]
Operating Revenue	$ 1,292		$ 1,634
Operating Expenses	1,153	[1]	1,485	[2]
Operating Income	139		149
Interest Expense	65		62
Other Income (Expenses)	8		9
Income Tax Expense (Benefit)	14		34
Net Income (Loss) from Continuing Operations	68		62
Total Assets	15,188		14,220		14,910
Construction Expenditures	291		171
Goodwill	1,407				1,407
Depreciation and amortization	110		105
Power Delivery [Member]
Segment Reporting Information [Line Items]
Operating Revenue	1,055		1,249
Operating Expenses	954	[1]	1,131	[2]
Operating Income	101		118
Interest Expense	53		50
Other Income (Expenses)	8		8
Income Tax Expense (Benefit)	9		29
Net Income (Loss) from Continuing Operations	47		47
Total Assets	11,473		10,667
Construction Expenditures	280		160
Goodwill	1,400		1,400
Depreciation and amortization	99		97
Pepco Energy Services [Member]
Segment Reporting Information [Line Items]
Operating Revenue	228		373
Operating Expenses	211	[1]	357	[2]
Operating Income	17		16
Interest Expense	1		1
Other Income (Expenses)			1
Income Tax Expense (Benefit)	6		6
Net Income (Loss) from Continuing Operations	10		10
Total Assets	544		613
Construction Expenditures	5		1
Depreciation and amortization	6		4
Other Non-Regulated [Member]
Segment Reporting Information [Line Items]
Operating Revenue	13		14
Operating Expenses	1	[1]	2	[2]
Operating Income	12		12
Interest Income	1		1
Interest Expense	3		3
Other Income (Expenses)	1		(1)
Preferred Stock Dividends	1		1
Income Tax Expense (Benefit)			2
Net Income (Loss) from Continuing Operations	10		6
Total Assets	1,487		1,645
Depreciation and amortization	1
Corporate And Other [Member]
Segment Reporting Information [Line Items]
Operating Revenue	(4)	[3]	(2)	[4]
Operating Expenses	(13)	[1],[3]	(5)	[2],[4]
Operating Income	9	[3]	3	[4]
Interest Income	(1)	[3]	(1)	[4]
Interest Expense	8	[3]	8	[4]
Other Income (Expenses)	(1)	[3]	1	[4]
Preferred Stock Dividends	(1)	[3]	(1)	[4]
Income Tax Expense (Benefit)	(1)	[3]	(3)	[4]
Net Income (Loss) from Continuing Operations	1	[3]	(1)	[4]
Total Assets	1,684	[3]	1,295	[4]
Construction Expenditures	6	[3]	10	[4]
Depreciation and amortization	4		4
Intersegment [Member]
Segment Reporting Information [Line Items]
Operating Revenue	(4)		(2)
Operating Expenses	(6)		(2)
Interest Income	(5)		(5)
Interest Expense	(5)		(4)
Preferred Stock Dividends	$ (1)		$ (1)

[1] Includes depreciation and amortization expense of $110 million, consisting of $99 million for Power Delivery, $6 million for Pepco Energy Services, $1 million for Other Non-Regulated and $4 million for Corporate and Other.

[2] Includes depreciation and amortization expense of $105 million, consisting of $97 million for Power Delivery, $4 million for Pepco Energy Services and $4 million for Corporate and Other.

[3] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to Power Delivery for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit Power Delivery. 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. Corporate and Other includes intercompany amounts of $(4) million for Operating Revenue, $(6) million for Operating Expenses, $(5) million for Interest Income, $(5) million for Interest Expense and $(1) million for Preferred Stock Dividends.

[4] Total Assets in this column includes Pepco Holdings' goodwill balance of $1.4 billion, all of which is allocated to Power Delivery for purposes of assessing impairment. Total assets also include capital expenditures related to certain hardware and software expenditures which primarily benefit Power Delivery. 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. Corporate and Other includes intercompany amounts of $(2) million for Operating Revenue, $(2) million for Operating Expenses, $(5) million for Interest Income, $(4) million for Interest Expense and $(1) million for Preferred Stock Dividends.