Consolidated Statements Of Equity (USD $) In Millions, except Share data, unless otherwise specified	Common Stock [Member] Potomac Electric Power Co [Member]	Common Stock [Member] Delmarva Power & Light Co/De [Member]	Common Stock [Member] Atlantic City Electric Co [Member]	Common Stock [Member]	Premium On Stock [Member] Potomac Electric Power Co [Member]	Premium On Stock [Member] Delmarva Power & Light Co/De [Member]	Premium On Stock [Member] Atlantic City Electric Co [Member]	Premium On Stock [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Retained Earnings [Member] Potomac Electric Power Co [Member]	Retained Earnings [Member] Delmarva Power & Light Co/De [Member]	Retained Earnings [Member] Atlantic City Electric Co [Member]	Retained Earnings [Member]	Potomac Electric Power Co [Member]	Delmarva Power & Light Co/De [Member]	Atlantic City Electric Co [Member]	Total
BALANCE at Dec. 31, 2011			$ 26	$ 2	$ 705	$ 347	$ 576	$ 3,325	$ (63)	$ 797	$ 505	$ 200	$ 1,072	$ 1,502	$ 852	$ 802	$ 4,336
Common Stock, Shares, Outstanding, Beginning Balance at Dec. 31, 2011	100	1,000	8,546,017	227,500,190										100	1,000	8,546,017	227,500,190
Net Income										24	21	2	68	24	21	2	68
Other comprehensive (loss) income									8								8
Dividends on common stock													(61)				(61)
Issuance of common stock
Original issue shares, net								9									9
Original issue shares, net, shares				319,037
Shareholder DRP original shares								8									8
Shareholder DRP original shares (in shares)				424,888
Net activity related to stock-based awards								(2)									(2)
BALANCE at Mar. 31, 2012			$ 26	$ 2	$ 705	$ 347	$ 576	$ 3,340	$ (55)	$ 821	$ 526	$ 202	$ 1,079	$ 1,526	$ 873	$ 804	$ 4,366
Common Stock, Shares, Outstanding, Ending Balance at Mar. 31, 2012	100	1,000	8,546,017	228,244,115										100	1,000	8,546,017	228,244,115