Property, Plant and Equipment (Details) (USD $)	12 Months Ended					37 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2012
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 61,043,000,000		$ 57,370,000,000			$ 57,370,000,000
Less: accumulated depreciation	(13,713,000,000)	[1]	(12,184,000,000)	[1]		(12,184,000,000)	[1]
Property, plant and equipment, net	47,330,000,000		45,186,000,000			45,186,000,000
Property Plant And Equipment Footnotes [Abstract]
Accumulated amortization of nuclear fuel	2,371,000,000
Plant Retirement Cost [Abstract]
Inventory write down related to plant retirements	9,000,000
Electric Transmission And Distribution [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	28,123,000,000		26,576,000,000			26,576,000,000
Electric Generation Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	20,420,000,000		19,004,000,000			19,004,000,000
Gas Distribution Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	3,296,000,000		3,108,000,000			3,108,000,000
Common Electric And Gas T And D Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,101,000,000		1,029,000,000			1,029,000,000
Nuclear Fuel [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	5,196,000,000	[2]	4,815,000,000	[2]		4,815,000,000	[2]
Public Utilities Property Plant And Equipment Construction Work In Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,890,000,000		1,926,000,000			1,926,000,000
Other Capitalized Property Plant And Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,017,000,000	[3]	912,000,000	[3]		912,000,000	[3]
Exelon Generation Co L L C [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	3.35%
Property Plant And Equipment [Line Items]
Total property, plant and equipment	27,145,000,000		25,545,000,000			25,545,000,000
Less: accumulated depreciation	(7,034,000,000)	[4]	(6,014,000,000)	[4]		(6,014,000,000)	[4]
Property, plant and equipment, net	20,111,000,000		19,531,000,000			19,531,000,000
Property Plant And Equipment Footnotes [Abstract]
Nuclear fuel - work in progress	947,000,000		894,000,000			894,000,000
Buildings under capital lease	23,000,000		20,000,000			20,000,000
Original cost basis for buildings	59,000,000
Accumulated depreciation for buildings	36,000,000		33,000,000			33,000,000
Accumulated amortization of nuclear fuel			2,078,000,000			2,078,000,000
Plant Retirements Details [Abstract]
Plant Retirement Cash Payments	2,000,000		4,000,000		4,000,000
Plant Retirement Cost [Abstract]
Plant retirement costs incurred						46,000,000
Severance benefits expense related to plant retirements	1,000,000				4,000,000	14,000,000
Inventory write down related to plant retirements	9,000,000		6,000,000			18,000,000
Plant shut-down costs	1,000,000		11,000,000		2,000,000	14,000,000
Exelon Generation Co L L C [Member] | Eddystone Generating Station [Member]
Plant Retirements Reliability Must Run Revenue [Abstract]
PlantMonthlyRevenueDuringReliabilityMustRunPeriod	6,000,000
Exelon Generation Co L L C [Member] | Schuylkill Station Unit One [Member]
Plant Retirement Positions Eliminated [Abstract]
Oil/gas-fired generation unit to be retired	166		166			166
Exelon Generation Co L L C [Member] | Riverside Station Unit Six [Member]
Plant Retirement Positions Eliminated [Abstract]
Oil/gas-fired generation unit to be retired	115
Exelon Generation Co L L C [Member] | Riverside Station Unit Four[Member]
Plant Retirement Positions Eliminated [Abstract]
Oil/gas-fired generation unit to be retired	74		115			115
Exelon Generation Co L L C [Member] | Electric Generation Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	20,420,000,000		19,004,000,000			19,004,000,000
Exelon Generation Co L L C [Member] | Electric Generation Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Exelon Generation Co L L C [Member] | Electric Generation Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	52 years
Exelon Generation Co L L C [Member] | Nuclear Fuel [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	5,196,000,000	[5]	4,815,000,000	[5]		4,815,000,000	[5]
Exelon Generation Co L L C [Member] | Nuclear Fuel [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Exelon Generation Co L L C [Member] | Nuclear Fuel [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	8 years
Exelon Generation Co L L C [Member] | Public Utilities Property Plant And Equipment Construction Work In Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,129,000,000		1,352,000,000			1,352,000,000
Exelon Generation Co L L C [Member] | Other Capitalized Property Plant And Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	400,000,000	[6]	374,000,000	[6]		374,000,000	[6]
Exelon Generation Co L L C [Member] | Other Capitalized Property Plant And Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	1 year
Exelon Generation Co L L C [Member] | Other Capitalized Property Plant And Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	51 years
Commonwealth Edison Co [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	17,850,000,000		16,824,000,000			16,824,000,000
Less: accumulated depreciation	(3,184,000,000)		(2,998,000,000)			(2,998,000,000)
Property, plant and equipment, net	14,666,000,000		13,826,000,000			13,826,000,000
Property Plant And Equipment Footnotes [Abstract]
Buildings under capital lease	8,000,000
Original cost basis for buildings	8,000,000
Plant Retirement Cost [Abstract]
Inventory write down related to plant retirements	0		1,000,000
Commonwealth Edison Co [Member] | Electric Transmission And Distribution [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	17,334,000,000		16,480,000,000			16,480,000,000
Commonwealth Edison Co [Member] | Electric Transmission And Distribution [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Commonwealth Edison Co [Member] | Electric Transmission And Distribution [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	75 years
Commonwealth Edison Co [Member] | Public Utilities Property Plant And Equipment Construction Work In Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	456,000,000		294,000,000			294,000,000
Commonwealth Edison Co [Member] | Other Capitalized Property Plant And Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	60,000,000	[7]	50,000,000	[7]		50,000,000	[7]
Property, plant and equipment, useful life	50 years
PECO Energy Co [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	9,319,000,000		8,875,000,000			8,875,000,000
Less: accumulated depreciation	(2,935,000,000)		(2,797,000,000)			(2,797,000,000)
Property, plant and equipment, net	6,384,000,000		6,078,000,000			6,078,000,000
PECO Energy Co [Member] | Electric Transmission And Distribution [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	6,669,000,000		6,355,000,000			6,355,000,000
PECO Energy Co [Member] | Electric Transmission And Distribution [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
PECO Energy Co [Member] | Electric Transmission And Distribution [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	65 years
PECO Energy Co [Member] | Gas Distribution Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,932,000,000		1,859,000,000			1,859,000,000
PECO Energy Co [Member] | Gas Distribution Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
PECO Energy Co [Member] | Gas Distribution Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	70 years
PECO Energy Co [Member] | Common Electric And Gas T And D Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	600,000,000		568,000,000			568,000,000
PECO Energy Co [Member] | Common Electric And Gas T And D Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
PECO Energy Co [Member] | Common Electric And Gas T And D Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	50 years
PECO Energy Co [Member] | Public Utilities Property Plant And Equipment Construction Work In Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	101,000,000		76,000,000			76,000,000
PECO Energy Co [Member] | Other Capitalized Property Plant And Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	17,000,000	[8]	17,000,000	[8]		17,000,000	[8]
PECO Energy Co [Member] | Other Capitalized Property Plant And Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	50 years
Baltimore Gas and Electric Company [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	8,566,000,000		8,093,000,000			8,093,000,000
Less: accumulated depreciation	(2,702,000,000)		(2,595,000,000)			(2,595,000,000)
Property, plant and equipment, net	5,864,000,000		5,498,000,000			5,498,000,000
Baltimore Gas and Electric Company [Member] | Electric Transmission And Distribution [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	6,100,000,000		5,767,000,000			5,767,000,000
Baltimore Gas and Electric Company [Member] | Electric Transmission And Distribution [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Baltimore Gas and Electric Company [Member] | Electric Transmission And Distribution [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	90 years
Baltimore Gas and Electric Company [Member] | Gas Distribution Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	1,660,000,000		1,548,000,000			1,548,000,000
Baltimore Gas and Electric Company [Member] | Gas Distribution Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Baltimore Gas and Electric Company [Member] | Gas Distribution Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	90 years
Baltimore Gas and Electric Company [Member] | Common Electric And Gas T And D Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	578,000,000		554,000,000			554,000,000
Baltimore Gas and Electric Company [Member] | Common Electric And Gas T And D Equipment [Member] | Minimum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Baltimore Gas and Electric Company [Member] | Common Electric And Gas T And D Equipment [Member] | Maximum [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, useful life	50 years
Baltimore Gas and Electric Company [Member] | Public Utilities Property Plant And Equipment Construction Work In Progress [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	196,000,000		193,000,000			193,000,000
Baltimore Gas and Electric Company [Member] | Other Capitalized Property Plant And Equipment [Member]
Property Plant And Equipment [Line Items]
Total property, plant and equipment	$ 32,000,000		$ 31,000,000			$ 31,000,000
Property, plant and equipment, useful life	20 years
Electric Transmission And Distribution [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	2.91%		2.76%		2.59%	2.76%
Electric Transmission And Distribution [Member] | PECO Energy Co [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	2.73%		2.51%		2.33%	2.51%
Electric Transmission And Distribution [Member] | Baltimore Gas and Electric Company [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	2.91%		2.92%		2.89%	2.92%
Electric Generation Equipment [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	3.35%		3.15%		3.12%	3.15%
Electric Generation Equipment [Member] | Exelon Generation Co L L C [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate			3.15%		3.12%	3.15%
Gas Distribution Equipment [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	2.06%		2.03%		1.73%	2.03%
Gas Distribution Equipment [Member] | PECO Energy Co [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	1.79%		1.77%		1.73%	1.77%
Gas Distribution Equipment [Member] | Baltimore Gas and Electric Company [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	2.36%		2.33%		2.41%	2.33%
Common Electric And Gas T And D Equipment [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	7.53%		7.61%		8.05%	7.61%
Common Electric And Gas T And D Equipment [Member] | PECO Energy Co [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	6.65%		7.54%		8.05%	7.54%
Common Electric And Gas T And D Equipment [Member] | Baltimore Gas and Electric Company [Member]
Property Plant And Equipment Average Service Life Percentage By Asset Category [Line Items]
Annual depreciation rate	8.45%		7.68%		8.40%	7.68%

[1] Includes accumulated amortization of nuclear fuel in the reactor core at Generation of $2,371 million and $2,078 million as of December 31, 2013 and 2012, respectively.

[2] ) Includes nuclear fuel that is in the fabrication and installation phase of $947 million and $894 million at December 31, 2013 and 2012, respectively.

[3] Includes Generation's buildings under capital lease with a net carrying value of $23 million and $20 million at December 31, 2013 and 2012, respectively. The original cost basis of the buildings was $59 million and total accumulated amortization was $36 million and $33 million as of December 31, 2013 and 2012, respectively. Also includes ComEd’s buildings under capital lease with a net carrying value of $8 million and $0 million at December 31, 2013 and 2012, respectively. The original cost basis of the buildings was $8 million and total accumulated amortization was $0 million and $0 million as of December 31, 2013 and 2012, respectively. Includes land held for future use and non utility property at PECO and BGE. These balances also include capitalized acquisition, development and exploration costs related to oil and gas production activities at Generation.

[4] Includes accumulated amortization of nuclear fuel in the reactor core of $2,371 million and $2,078 million as of December 31, 2013 and 2012, respectively.

[5] Includes nuclear fuel that is in the fabrication and installation phase of $947 million and $894 million at December 31, 2013 and 2012, respectively.

[6] Includes buildings under capital lease with a net carrying value of $23 million and $20 million at December 31, 2013 and 2012, respectively. The original cost basis of the buildings was $59 million and total accumulated amortization was $36 million and $33 million as of December 31, 2013 and 2012, respectively. These balances also include capitalized acquisition, development and exploration costs related to oil and gas production activities.

[7] Includes buildings under capital lease with a net carrying value of $8 million and $0 million at December 31, 2013 and 2012, respectively. The original cost basis of the buildings was $8 million and total accumulated amortization was $0 million and $0 million as of December 31, 2013 and 2012, respectively.

[8] Represents land held for future use and non utility property.