Property, Plant and Equipment (Details) (USD $)	Jun. 30, 2012		Dec. 31, 2011
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	$ (11,367,000,000)	[1]	$ (10,959,000,000)	[2]
Property, plant and equipment, net	42,613,000,000		32,570,000,000
Property Plant And Equipment Footnotes [Abstract]
Accumulated amortization of nuclear fuel	1,951,000,000		1,784,000,000
Exelon Generation Co L L C [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(5,526,000,000)	[1]	(5,313,000,000)	[2]
Property, plant and equipment, net	17,702,000,000		13,475,000,000
Property Plant And Equipment Footnotes [Abstract]
Accumulated amortization of nuclear fuel	1,951,000,000		1,784,000,000
Commonwealth Edison Co [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(2,844,000,000)		(2,750,000,000)
Property, plant and equipment, net	13,428,000,000		13,121,000,000
PECO Energy Co [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(2,731,000,000)		(2,662,000,000)
Property, plant and equipment, net	5,960,000,000		5,874,000,000
Baltimore Gas and Electric Company [Member]
Property Plant And Equipment [Line Items]
Less: accumulated depreciation	(2,549,000,000)		(2,465,000,000)
Property, plant and equipment, net	$ 5,294,000,000		$ 5,132,000,000

[1] Includes accumulated amortization of nuclear fuel in the reactor core of $1,951 million.

[2] Includes accumulated amortization of nuclear fuel in the reactor core of $1,784 million.