Commitments And Contingencies (Tax Legislation, Guarantees, And Dividends) (Details) (USD $) In Millions, except Per Share data	0 Months Ended	6 Months Ended
Jul. 28, 2011	Jun. 30, 2011
Guarantee payout on guarantee contract		$ 1
Dividend declared on common stock, per share	$ 0.27
Pepco Energy Services [Member]
Liability for guarantee contracts, current value		$ 397
Longest remaining term of guarantees, in years		15

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

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