Debt and Credit Agreements (Details) (USD $)	3 Months Ended			3 Months Ended														3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Mar. 31, 2014 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] Fair Value Hedging [Member]	Dec. 31, 2013 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] Fair Value Hedging [Member]	Mar. 31, 2014 Exelon Corporate [Member]	Mar. 31, 2014 Exelon Corporate [Member] Syndicated Revolver [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Commercial Paper [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Syndicated Revolver [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Letter of Credit [Member]	Jan. 23, 2013 Exelon Generation Co L L C [Member] Letter of Credit [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] ExgenRenewablesI425June62021[Member] Interest Rate Swap [Member]	Mar. 31, 2013 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] UpstreamGasLending221July222016[Member]	Mar. 31, 2013 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] DOE Financing Project [Member] DOE Project Financing, 3.092% January 2, 2037 [Member]	Mar. 31, 2013 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] DOE Financing Project [Member] Floating Rate Debt [Member] DOE Project Financing, 3.092% January 2, 2037 [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] Non Recourse Debt [Member] ExgenRenewablesI425June62021[Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Long Term Debt Retirements [Member] Continental Wind 6000 February 28, 2033 [Member] Continetal Wind [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Long Term Debt Retirements [Member] Capital Lease Obligations [Member] Kennett Square Capital Lease, 7.83%, September 20, 2020 [Member]	Mar. 31, 2013 Exelon Generation Co L L C [Member] Long Term Debt Retirements [Member] Capital Lease Obligations [Member] Kennett Square Capital Lease, 7.83%, September 20, 2020 [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Long Term Debt Retirements [Member] Senior Notes [Member] SeniorSecuredNotes525January152014Member [Member]	Mar. 31, 2014 Exelon Generation Co L L C [Member] Long Term Debt Retirements [Member] Pollution Control Notes [Member] Fixed Rate Debt [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member]	Mar. 14, 2013 Commonwealth Edison Co [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Commercial Paper [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Syndicated Revolver [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Long Term Debt Issuances [Member] First Mortgage Bonds [Member] FirstMortgageBondSeries215January152019 [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Long Term Debt Issuances [Member] First Mortgage Bonds [Member] FirstMortgageBondSeries47January152044Member [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Long Term Debt Retirements [Member] First Mortgage Bonds [Member] FirstMortgageBond163January12014 [Member]	Mar. 31, 2014 Commonwealth Edison Co [Member] Long Term Debt Retirements [Member] Pollution Control Notes [Member] Fixed Rate Debt [Member]	Mar. 31, 2014 PECO Energy Co [Member]	Dec. 31, 2013 PECO Energy Co [Member]	Mar. 31, 2014 PECO Energy Co [Member] Syndicated Revolver [Member]	Mar. 31, 2014 Baltimore Gas and Electric Company [Member]	Dec. 31, 2013 Baltimore Gas and Electric Company [Member]	Mar. 31, 2014 Baltimore Gas and Electric Company [Member] Commercial Paper [Member]	Mar. 31, 2014 Baltimore Gas and Electric Company [Member] Syndicated Revolver [Member]
Long-Term Debt [Abstract]
Long-term debt to affiliate								$ 1,517,000,000	$ 1,523,000,000
Non-Recourse Debt - Interest Rate Swap																240,000,000
Long-term debt to financing trusts	648,000,000		648,000,000																							206,000,000	206,000,000								184,000,000	184,000,000		258,000,000	258,000,000
Interest rate on long-term debt																	2.21%			4.25%	6.00%	7.83%	7.83%	5.35%	4.10%						2.15%	4.70%	1.63%	5.85%
Minimum interest rate on long-term debt																		0.0272%
Maximum interest rate on long-term debt																		0.0281%
Long Term Debt																	3,000,000			300,000,000	11,000,000	1,000,000		500,000,000	20,000,000						300,000,000	350,000,000	600,000,000	17,000,000
Derivative, Gain on Derivative	4,000,000	1,000,000		2,000,000
DebtInstrumentCollateralAmount	1,900,000,000
Long-term Debt, Excluding Current Maturities	18,247,000,000		17,325,000,000					5,840,000,000	5,559,000,000										146,000,000				1,000,000			5,707,000,000	5,058,000,000								1,947,000,000	1,947,000,000		1,746,000,000	1,746,000,000
Footnotes To Long-Term Debt [Abstract]
Notional amount of interest rate cash flow hedge derivatives				1,400,000,000	1,275,000,000									164,000,000	195,000,000
Line Of Credit Facility [Abstract]
LineOfCreditFacilityMaximumBorrowingCapacity	8,400,000,000						500,000,000				5,300,000,000																			1,000,000,000							600,000,000				600,000,000
Outstanding letters of credit												300,000,000	100,000,000
Footnotes To Line Of Credit Facility [Abstract]
Credit facility agreements with minority and community banks								50,000,000																		34,000,000									34,000,000			5,000,000
Letters of credit								20,000,000																		17,000,000									21,000,000			1,000,000
ShortTermBorrowingsAbstract
Commercial paper borrowings										352,000,000																			534,000,000											69,000,000
Short-term debt outstanding amount	980,000,000		341,000,000					377,000,000	22,000,000																	534,000,000	184,000,000											69,000,000	135,000,000
Credit Agreements [Abstract]
Additional amounts available upon request under current credit facilities																												500,000,000
Basis points adders for prime-based borrowings						0.275		0.275																		0.075									0			0
Basis points adders for LIBOR-based borrowings						1.275		1.275																		1.075									0.900			1
Amount Of Aggregate Letters of Credit Available																												500,000,000
Revolver Under Amendment																												$ 1,000,000,000