Subsequent Event (Details) (USD $)	9 Months Ended
	Sep. 30, 2012 Customers
PECO Energy Co [Member]
Storm Damage Impact [Abstract]
Customers impacted from storm damage	850,000
Incremental operating and maintenance expense from storm damage (low estimate)	$ 49,000,000
Incremental operating and maintenance expense from storm damage (high estimate)	55,000,000
Incremental capital expenditures from storm damage (low estimate)	32,000,000
Incremental capital expenditures from storm damage (high estimate)	36,000,000
Baltimore Gas and Electric Company [Member]
Storm Damage Impact [Abstract]
Customers impacted from storm damage	325,000
Incremental operating and maintenance expense from storm damage (low estimate)	33,000,000
Incremental operating and maintenance expense from storm damage (high estimate)	37,000,000
Incremental capital expenditures from storm damage (low estimate)	13,000,000
Incremental capital expenditures from storm damage (high estimate)	$ 14,000,000