Discontinued Operations (Derivative Gain (Loss) for Conectiv Energy Included in (Loss) Income from Discontinued Operations) (Details) (Conectiv Energy [Member], USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2010	Jun. 30, 2010
Conectiv Energy [Member]
Realized mark-to-market gains	$ 23	$ 26
Unrealized mark-to-market (losses) gains	(23)	(24)
Total net mark-to-market gains (losses)		$ 2

The increases (decreases) in the market value of derivative instruments, including options, swaps, futures, and forward contracts, which were included in earnings in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28

Name:	us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration