Debt and Credit Agreements (Details) (USD $)	12 Months Ended																							12 Months Ended						12 Months Ended				12 Months Ended		12 Months Ended				12 Months Ended				12 Months Ended						12 Months Ended															12 Months Ended				12 Months Ended		12 Months Ended			12 Months Ended	9 Months Ended	12 Months Ended							12 Months Ended				0 Months Ended							12 Months Ended							12 Months Ended																				12 Months Ended					12 Months Ended										12 Months Ended
	Dec. 31, 2013 CreditAgreementThreshold BasisPoints		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2013 Commercial Paper [Member]	Dec. 31, 2013 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] Fair Value Hedging [Member]	Dec. 31, 2012 Designated as Hedging Instrument [Member] Interest Rate Swap [Member] Fair Value Hedging [Member]	Dec. 31, 2013 ComEd Financing Three Affiliate [Member]		Dec. 31, 2012 ComEd Financing Three Affiliate [Member]		Dec. 31, 2013 PECO Trust Three Affiliate [Member]		Dec. 31, 2012 PECO Trust Three Affiliate [Member]		Dec. 31, 2013 PECO Trust Four Affiliate [Member]		Dec. 31, 2012 PECO Trust Four Affiliate [Member]		Dec. 31, 2013 Baltimore Gas Electric Trust [Member]		Dec. 31, 2012 Baltimore Gas Electric Trust [Member]	Dec. 31, 2013 Rate Stabilization Bonds, April 1, 2017 [Member]	Dec. 31, 2012 Rate Stabilization Bonds, April 1, 2017 [Member]	Dec. 31, 2012 Fixed Rate Debt [Member]	Dec. 31, 2012 Floating Rate Debt [Member]	Dec. 31, 2013 Capital Lease Obligations [Member]	Dec. 31, 2012 Capital Lease Obligations [Member]	Dec. 31, 2013 Notes Payable To Banks [Member]		Dec. 31, 2012 Notes Payable To Banks [Member]		Dec. 31, 2013 Senior Notes [Member]	Dec. 31, 2012 Senior Notes [Member]	Dec. 31, 2013 First Mortgage Bonds [Member] Fixed Rate Debt [Member]		Dec. 31, 2012 First Mortgage Bonds [Member] Fixed Rate Debt [Member]		Dec. 31, 2013 First Mortgage Bonds [Member] Floating Rate Debt [Member]	Dec. 31, 2013 Pollution Control Notes [Member]	Dec. 31, 2013 Pollution Control Notes [Member] Fixed Rate Debt [Member]	Dec. 31, 2012 Pollution Control Notes [Member] Fixed Rate Debt [Member]	Dec. 31, 2013 Non Recourse Debt [Member] Fixed Rate Debt [Member]	Dec. 31, 2013 Non Recourse Debt [Member] Floating Rate Debt [Member]	Jun. 28, 2012 Long Term Debt Assumed [Member]	Dec. 31, 2013 Long Term Debt Assumed [Member] Fixed Rate Note, 4.55% Due 2015 [Member]	Dec. 31, 2013 Long Term Debt Assumed [Member] Notes, 5.15% Due 2020 [Member]	Dec. 31, 2013 Long Term Debt Exchange Offer Exchanged [Member] Senior Notes, 7.6% Due 2032 [Member]	Dec. 31, 2013 Exelon Corporate [Member] BasisPoints		Dec. 31, 2012 Exelon Corporate [Member]		Dec. 31, 2013 Exelon Generation Co L L C [Member] BasisPoints CreditAgreementThreshold		Dec. 31, 2012 Exelon Generation Co L L C [Member]		Dec. 31, 2011 Exelon Generation Co L L C [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Designated as Hedging Instrument [Member] Foreign Exchange Contract [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Designated as Hedging Instrument [Member] Interest Rate Swap [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Designated as Hedging Instrument [Member] Interest Rate Swap [Member] Cash Flow Hedging [Member]	Dec. 31, 2012 Exelon Generation Co L L C [Member] Floating Rate Debt [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Capital Lease Obligations [Member]	Dec. 31, 2012 Exelon Generation Co L L C [Member] Capital Lease Obligations [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Notes Payable To Banks [Member]		Dec. 31, 2012 Exelon Generation Co L L C [Member] Notes Payable To Banks [Member]		Dec. 31, 2013 Exelon Generation Co L L C [Member] Senior Notes [Member]	Dec. 31, 2012 Exelon Generation Co L L C [Member] Senior Notes [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Pollution Control Notes [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Pollution Control Notes [Member] Fixed Rate Debt [Member]	Dec. 31, 2012 Exelon Generation Co L L C [Member] Pollution Control Notes [Member] Fixed Rate Debt [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member]	Sep. 30, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Constellation Solar Horizons Financing [Member] MW	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Constellation Solar Horizons Financing [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Sacramento PV Energy [Member]	Dec. 31, 2012 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Sacramento PV Energy [Member] MW	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Secured Solar Credit Lending Agreement [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Holyoke [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Denver International Airport [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Upstream Gas Property [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Fixed Rate Debt [Member]	Dec. 31, 2013 Exelon Generation Co L L C [Member] Non Recourse Debt [Member] Floating Rate Debt [Member]	Jun. 18, 2012 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] Senior Notes, 4.25% June 15, 2022 [Member]	Jun. 18, 2012 Exelon Generation Co L L C [Member] Long Term Debt Issuances [Member] Senior Notes, 5.6% June 15, 2042 [Member]	Jun. 28, 2012 Exelon Generation Co L L C [Member] Long Term Debt Assumed [Member]	Jun. 18, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Issued And Sold [Member]	Jun. 18, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Issued And Sold [Member] Senior Notes [Member]	Jun. 28, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Purchased [Member]	Jul. 13, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Exchanged [Member]	Jun. 28, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Exchanged [Member]	Jun. 18, 2012 Exelon Generation Co L L C [Member] Long Term Debt Exchange Offer Exchanged [Member] Senior Notes, 7.6% Due 2032 [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] CreditAgreementThreshold		Dec. 31, 2012 Commonwealth Edison Co [Member]		Dec. 31, 2011 Commonwealth Edison Co [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] Commercial Paper [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] WillisTowerCapitalLease749May12053Member [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] Fixed Rate Debt [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] Notes Payable To Banks [Member]	Dec. 31, 2012 Commonwealth Edison Co [Member] Notes Payable To Banks [Member]	Dec. 31, 2013 Commonwealth Edison Co [Member] First Mortgage Bonds [Member]		Dec. 31, 2012 Commonwealth Edison Co [Member] First Mortgage Bonds [Member]		Dec. 31, 2013 Commonwealth Edison Co [Member] Suboridanted Debentures [Member]	Dec. 31, 2013 PECO Energy Co [Member] BasisPoints CreditAgreementThreshold		Dec. 31, 2012 PECO Energy Co [Member]		Dec. 31, 2013 PECO Energy Co [Member] PECO Trust Three Affiliate [Member]		Dec. 31, 2012 PECO Energy Co [Member] PECO Trust Three Affiliate [Member]		Dec. 31, 2013 PECO Energy Co [Member] PECO Trust Four Affiliate [Member]		Dec. 31, 2012 PECO Energy Co [Member] PECO Trust Four Affiliate [Member]		Dec. 31, 2013 PECO Energy Co [Member] First Mortgage Bonds [Member]	Dec. 31, 2013 PECO Energy Co [Member] First Mortgage Bonds [Member] Fixed Rate Debt [Member]		Dec. 31, 2012 PECO Energy Co [Member] First Mortgage Bonds [Member] Fixed Rate Debt [Member]		Dec. 31, 2013 Baltimore Gas and Electric Company [Member] BasisPoints CreditAgreementThreshold		Dec. 31, 2012 Baltimore Gas and Electric Company [Member]		Dec. 31, 2011 Baltimore Gas and Electric Company [Member]	Dec. 31, 2013 Baltimore Gas and Electric Company [Member] Commercial Paper [Member]	Dec. 31, 2013 Baltimore Gas and Electric Company [Member] Baltimore Gas Electric Trust [Member]		Dec. 31, 2012 Baltimore Gas and Electric Company [Member] Baltimore Gas Electric Trust [Member]		Dec. 31, 2013 Baltimore Gas and Electric Company [Member] Rate Stabilization Bonds, April 1, 2017 [Member]	Dec. 31, 2012 Baltimore Gas and Electric Company [Member] Rate Stabilization Bonds, April 1, 2017 [Member]
Long-Term Debt [Abstract]
Secured Long Term Debt																																				$ 7,746,000,000	[1],[2]	$ 7,397,000,000	[1],[2]																																																																	$ 5,546,000,000	[3],[4]	$ 5,447,000,000	[3],[4]
Unsecured Long Term Debt	1,750,000,000		1,850,000,000																															7,571,000,000	8,021,000,000																																		6,271,000,000	6,721,000,000																																																								1,750,000,000		1,850,000,000
Long-term debt to affiliate																																																								2,007,000,000
Long Term Notes Payable																														181,000,000	[5]	177,000,000	[5]																																33,000,000	[5]	30,000,000	[5]																																		148,000,000	140,000,000
Long Term Pollution Control Bond																																										20,000,000	20,000,000																													20,000,000	20,000,000
Non-recourse debt																																																																											38,000,000	38,000,000	39,000,000	41,000,000	113,000,000	11,000,000	7,000,000	72,000,000
Non-Recourse Debt - MW																																																																											16			30
Non-Recourse Debt - Term																																																																												18 years			3 years
Non-Recourse Debt - Commitment																																																																															150,000,000			150,000,000
Non-Recourse Debt - Commitment Increase Available																																																																															200,000,000			500,000,000
Non-Recourse Debt - Interest Rate Swap																																																																												29,000,000	29,000,000
Non-Recourse Debt - Hedge Percentage																																																																												75.00%	75.00%
Total long-term debt	18,760,000,000		18,297,000,000																																																			7,552,000,000		7,271,000,000																																						5,694,000,000		5,587,000,000													1,947,000,000		1,647,000,000															2,015,000,000		2,182,000,000
Unamortized debt discount and premium, net	(19,000,000)		(17,000,000)																																																			(11,000,000)		(13,000,000)																																						19,000,000		20,000,000													3,000,000		3,000,000															4,000,000		4,000,000
Unamortized settled fair value hedge, net	(384,000,000)		(448,000,000)
Fair value hedge carrying value adjustment, net	7,000,000		17,000,000
Long-term debt due within one year	(1,509,000,000)		(1,047,000,000)																																																			(561,000,000)		(28,000,000)																																						617,000,000		252,000,000													(250,000,000)		(300,000,000)															(70,000,000)		(467,000,000)
Long-term debt	17,325,000,000		17,190,000,000																					265,000,000	332,000,000	238,000,000	262,000,000																	1,077,000,000	150,000,000		550,000,000	550,000,000	700,000,000					5,559,000,000		5,245,000,000						262,000,000																					1,077,000,000	150,000,000						441,000,000	1,000,000			5,058,000,000		5,315,000,000													1,947,000,000		1,647,000,000											2,200,000,000	[6],[7]	1,950,000,000	[6],[7]	1,746,000,000		1,446,000,000								265,000,000	332,000,000
Total long-term debt with adjustments	17,623,000,000		17,698,000,000																																																			7,168,000,000		7,455,000,000																																																																						1,941,000,000		1,711,000,000
Long-term debt to PECO Energy Transition Trust due within one year																																																																																																													0		0
Subordinated debentures																																																																																														206,000,000	[8]	206,000,000	[8]
Total long-term debt to financing trusts	648,000,000	[9]	648,000,000	[9]																																																																																																																																	[10]		[10]
Long-term debt to financing trusts	298,000,000		648,000,000						206,000,000	[9]	206,000,000	[9]	81,000,000	[9]	81,000,000	[9]	103,000,000	[9]	103,000,000	[9]	258,000,000	[9]	258,000,000																															1,523,000,000															1,808,000,000																									206,000,000		206,000,000													184,000,000	[11]	184,000,000	[11]	81,000,000	[11]	81,000,000	[11]	103,000,000	[11]	103,000,000	[11]						258,000,000		258,000,000				258,000,000	[10]	258,000,000	[10]
Interest rate on long-term debt									6.35%				7.38%				5.75%				6.20%																										4.55%	5.15%																																					4.25%	5.60%							7.60%									6.95%						6.35%					7.38%				5.75%															6.20%
Minimum interest rate on long-term debt																								5.68%						4.50%				2.00%		1.20%				2.80%	4.10%			2.33%	1.96%																				4.50%				2.00%		4.10%			2.33%										1.96%																	1.63%																					1.20%				2.80%										5.68%
Maximum interest rate on long-term debt																								5.82%						7.83%				7.60%		7.63%				6.35%				5.50%	2.77%																				7.83%				7.60%														5.50%	2.77%																	7.63%	7.49%																			5.95%					6.35%										5.82%
Long Term Debt	19,408,000,000																																																					7,552,000,000																																			775,000,000			535,000,000		5,900,000,000															2,384,000,000																	2,273,000,000
Long term debt old notes	258,000,000																																													608,000,000
Cash payment related to exchange offer																																																																																												60,000,000
Increase in fair value adjustment	403,000,000																																																																																						13,000,000
Fair Value Adjustment Outstanding	199,000,000																																																					166,000,000		199,000,000
Derivative, Gain on Derivative	11,000,000
Footnotes To Long-Term Debt [Abstract]
Capital Leases Future Minimum Payments Due Current																												3,000,000																																			3,000,000
Capital Leases Future Minimum Payments Due In Two Years																												3,000,000																																			3,000,000
Capital Leases Future Minimum Payments Due In Three Years																												3,000,000																																			3,000,000
Capital Leases Future Minimum Payments Due In Four Years																												4,000,000																																			4,000,000
Capital Leases Future Minimum Payments Due In Five Years																												4,000,000																																			4,000,000
Capital Leases Future Minimum Payments Due Thereafter																												13,000,000																																			13,000,000																																					7,000,000
Capital Lease Obligations Noncurrent																												30,000,000	34,000,000																																		30,000,000	34,000,000																																				8,000,000
Notional amount of interest rate cash flow hedge derivatives	2,651,000,000		2,498,000,000				1,275,000,000	650,000,000																																																			195,000,000	144,000,000	470,000,000
Loss on interest rate swap																																																																																								7,000,000
Line Of Credit Facility [Abstract]
Aggregate bank commitments under unsecured revolving credit facilities	8,375,000,000																																																	500,000,000				5,675,000,000																																								1,000,000,000															600,000,000																	600,000,000
Outstanding borrowings/facility draws	1,416,000,000																																																	2,000,000				1,413,000,000																																																							1,000,000
Outstanding letters of credit	200,000,000																																																					3,500,000,000																																								500,000,000															300,000,000																	600,000,000
Actual available capacity	6,959,000,000																																																	498,000,000				4,262,000,000																																								1,000,000,000															599,000,000																	600,000,000
Available capacity to support additional commercial paper borrowings	6,565,000,000																																																	498,000,000				4,187,000,000																																								816,000,000															599,000,000																	465,000,000
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																																								18,000,000															21,000,000																	1,000,000
ShortTermBorrowingsAbstract
Average Interest Rate On Commercial Paper Borrowings																																																		0.27%		0.47%		0.32%		0.45%																																						0.40%		0.50%																														0.31%		0.43%
Maximum borrowings outstanding	682,000,000		505,000,000		600,000,000																																																	291,000,000		165,000,000		304,000,000																																				446,000,000		366,000,000		407,000,000																												135,000,000		76,000,000		190,000,000
Maximum program size	8,300,000,000	[12]	8,300,000,000	[12]																																														500,000,000	[12]	500,000,000	[12]	5,600,000,000	[12]	5,600,000,000	[12]																																					1,000,000,000	[12]	1,000,000,000	[12]												600,000,000	[12]	600,000,000	[12]														600,000,000	[12]	600,000,000	[12]
Commercial paper borrowings			0			319,000,000																																														0																																															184,000,000																																135,000,000
Short-term debt outstanding amount	341,000,000																																																					22,000,000		0																																						184,000,000		0																														135,000,000
Average borrowings	254,000,000		199,000,000		218,000,000																																																	42,000,000		4,000,000		51,000,000																																				203,000,000		110,000,000		36,000,000																												35,000,000		6,000,000		26,000,000
Average interest rates, computed on a daily basis	0.37%		0.48%		0.50%																																																	0.32%		0.45%		0.48%																																				0.40%		0.50%		0.71%																												0.31%		0.43%		0.38%
Credit Agreements [Abstract]
Additional amounts available upon request under current credit facilities	250,000,000																																																					1,000,000,000																																								500,000,000															250,000,000																	100,000,000
Amount that would constitute an event of default																																																						100,000,000
Basis points adders for prime-based borrowings																																																		0.00275				0.00075																																																																								0.00075
Basis points adders for LIBOR-based borrowings																																																		0.01275				0.01075																																																							0.01																	0.01075
Bilateral letters of credit																																																						75,000,000
Basis Points For Prime Based Borrowings Current	0.0065
Basis Points For LIBOR Based Borrowings Current	0.0165
Previous Aggregate Commitments Of Acquired Entity	2,500,000,000
Amended Aggregate Commitments Of Acquired Entity	$ 1,500,000,000
Credit agreement interest coverage minimum threshold	2.50																																																					3.00																																								2.00															2.00																	2.00
Debt Covenant Actual	7.67%																																																					11.45%																																								5.20%															8.29%																	7.85%

[1] Substantially all of ComEd's assets other than expressly excepted property and substantially all of PECO's assets are subject to the liens of their respective mortgage indentures.

[2] Includes First Mortgage Bonds issued under the ComEd and PECO mortgage indentures securing pollution control bonds and notes.

[3] Substantially all of ComEd's assets other than expressly excepted property are subject to the lien of its mortgage indenture.

[4] Includes First Mortgage Bonds issued under the ComEd mortgage indenture securing pollution control bonds and notes.

[5] Includes capital lease obligations of $41 million and $30 million at December 31, 2013 and 2012, respectively. Lease payments of $4 million, $4 million, $4 million, $5 million, $5 million and $19 million will be made in 2014, 2015, 2016, 2017, 2018 and thereafter, respectively.

[6] Substantially all of PECO's assets are subject to the lien of its mortgage indenture.

[7] Includes First Mortgage Bonds issued under the PECO mortgage indenture securing pollution control bonds and notes.

[8] Amount owed to this financing trust is recorded as debt to financing trust within ComEd's Consolidated Balance Sheets.

[9] Amounts owed to these financing trusts are recorded as debt to financing trusts within Exelon's Consolidated Balance Sheets.

[10]  (a)        Amount owed to this financing trust is recorded as debt to financing trust within BGE's Consolidated Balance Sheets.

[11] Amounts owed to this financing trust are recorded as debt to financing trusts within PECO's Consolidated Balance Sheets.

[12] (a) Equals aggregate bank commitments under the revolving and bilateral credit agreements (with the exception of a $75 million bilateral agreement) that backstop the commercial paper program. See discussion below and Credit Agreements table below for items affecting effective program size.