Property, Plant and Equipment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Dec. 31, 2013
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	$ (14,066)	[1]	$ (13,713)	[2]
Property, plant and equipment, net	47,742		47,330
Property Plant And Equipment Footnotes [Abstract]
Accumulated amortization of nuclear fuel	2,425		2,371
Plant Retirement Cost [Abstract]
Inventory write down related to plant retirements	2
Exelon Generation Co L L C [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(7,245)	[1]	(7,034)	[2]
Property, plant and equipment, net	20,132		20,111
Property Plant And Equipment Footnotes [Abstract]
Accumulated amortization of nuclear fuel	2,425		2,371
Plant Retirement Cost [Abstract]
Inventory write down related to plant retirements	2
Commonwealth Edison Co [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(3,247)		(3,184)
Property, plant and equipment, net	14,890		14,666
PECO Energy Co [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(2,958)		(2,935)
Property, plant and equipment, net	6,480		6,384
Baltimore Gas and Electric Company [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(2,741)		(2,702)
Property, plant and equipment, net	$ 5,939		$ 5,864

[1] Includes accumulated amortization of nuclear fuel in the reactor core of $2,425 million.

[2] Includes accumulated amortization of nuclear fuel in the reactor core of $2,371 million.