Debt and Credit Agreements (Maturitites of Long-term Debt) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Long Term Debt By Maturity [Abstract]
Long Term Debt Maturities Repayments Of Principal In Next Twelve Months	$ 1,428
Long Term Debt Maturities Repayments Of Principal In Year Two	1,615
Long Term Debt Maturities Repayments Of Principal In Year Three	1,346
Long Term Debt Maturities Repayments Of Principal In Year Four	1,396
Long Term Debt Maturities Repayments Of Principal In Year Five	1,345
Long Term Debt Maturities Repayments Of Principal After Year Five	12,278	[1]
Long Term Debt	19,408
Exelon Generation Co L L C [Member]
Long Term Debt By Maturity [Abstract]
Long Term Debt Maturities Repayments Of Principal In Next Twelve Months	561
Long Term Debt Maturities Repayments Of Principal In Year Two	555
Long Term Debt Maturities Repayments Of Principal In Year Three	81
Long Term Debt Maturities Repayments Of Principal In Year Four	706
Long Term Debt Maturities Repayments Of Principal In Year Five	5
Long Term Debt Maturities Repayments Of Principal After Year Five	5,644
Long Term Debt	7,552
Commonwealth Edison Co [Member]
Long Term Debt By Maturity [Abstract]
Long Term Debt Maturities Repayments Of Principal In Next Twelve Months	617
Long Term Debt Maturities Repayments Of Principal In Year Two	260
Long Term Debt Maturities Repayments Of Principal In Year Three	665
Long Term Debt Maturities Repayments Of Principal In Year Four	425
Long Term Debt Maturities Repayments Of Principal In Year Five	840
Long Term Debt Maturities Repayments Of Principal After Year Five	3,093	[2]
Long Term Debt	5,900
PECO Energy Co [Member]
Long Term Debt By Maturity [Abstract]
Long Term Debt Maturities Repayments Of Principal In Next Twelve Months	250
Long Term Debt Maturities Repayments Of Principal In Year Two	0
Long Term Debt Maturities Repayments Of Principal In Year Three	300
Long Term Debt Maturities Repayments Of Principal In Year Four	0
Long Term Debt Maturities Repayments Of Principal In Year Five	500
Long Term Debt Maturities Repayments Of Principal After Year Five	1,334	[3]
Long Term Debt	2,384
Baltimore Gas and Electric Company [Member]
Long Term Debt By Maturity [Abstract]
Long Term Debt Maturities Repayments Of Principal In Next Twelve Months	0
Long Term Debt Maturities Repayments Of Principal In Year Two	0
Long Term Debt Maturities Repayments Of Principal In Year Three	300
Long Term Debt Maturities Repayments Of Principal In Year Four	265
Long Term Debt Maturities Repayments Of Principal In Year Five	0
Long Term Debt Maturities Repayments Of Principal After Year Five	1,708	[4]
Long Term Debt	$ 2,273

[1] )        Includes $648 million due to ComEd, PECO and BGE financing trusts.

[2] Includes $206 million due to ComEd financing trust.

[3] Includes $184 million due to PECO financing trusts.

[4] Includes $258 million due to BGE financing trust.