Income Taxes (Tables)

3 Months Ended

Mar. 31, 2013

Reconciliation Of Effective Income Tax Rate From Continuing Operations

	Three Months Ended March 31,
	2013					2012
	(millions of dollars)
Income tax at Federal statutory rate	$	(103	)	35.0	%	$	26		35.0	%
Increases (decreases) resulting from:
State income taxes, net of Federal effect		5		(1.7	)%		4		5.4	%
Asset removal costs		(3	)	1.0	%		(3	)	(4.1	)%
Changes in estimates and interest related to uncertain and effectively settled tax positions		67		(22.7	)%		(13	)	(17.6	)%
Cross-border energy lease investments		64		(21.7	)%		(1	)	(1.4	)%
Establishment of valuation allowances related to deferred tax assets		101		(34.2	)%		—		—
Other, net		4		(1.5	)%		(2	)	(2.4	)%
Consolidated income tax expense related to continuing operations	$	135		(45.8	)%	$	11		14.9	%

Delmarva Power & Light Co/De [Member]

Reconciliation Of Effective Income Tax Rate From Continuing Operations

	Three Months Ended March 31,
	2013					2012
	(millions of dollars)
Income tax at Federal statutory rate	$	15		35.0	%	$	12	35.0	%
Increases (decreases) resulting from:
State income taxes, net of Federal effect		2		4.7	%		2	5.7	%
Changes in estimates and interest related to uncertain and effectively settled tax positions		(1	)	(2.4	)%		—	—
Other, net		—		0.8	%		—	(0.7	)%
Income tax expense	$	16		38.1	%	$	14	40.0	%

Potomac Electric Power Co [Member]

Reconciliation Of Effective Income Tax Rate From Continuing Operations

	Three Months Ended March 31,
	2013					2012
	(millions of dollars)
Income tax at Federal statutory rate	$	9		35.0	%	$	7		35.0	%
Increases (decreases) resulting from:
State income taxes, net of Federal effect		2		8.0	%		1		6.3	%
Asset removal costs		(3	)	(12.0	)%		(3	)	(15.8	)%
Changes in estimates and interest related to uncertain and effectively settled tax positions		(5	)	(20.0	)%		(10	)	(50.5	)%
Other, net		(1	)	(3.0	)%		—		(1.3	)%
Income tax expense (benefit)	$	2		8.0	%	$	(5	)	(26.3	)%