Significant Accounting Policies (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	May 15, 2014	Dec. 31, 2013
Capitalized Interest And AFUDC [Line Items]
Total interest incurred					$ 8,000,000
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Operating and maintenance	2,166,000,000	1,000,000	1,892,000,000	4,024,000,000	3,656,000,000
Interest Expense	228,000,000		246,000,000	445,000,000	863,000,000
Consolidation Percentages Detail Tagging [Abstract]
Equity Method Investment Ownership Percentage						67.00%
Third Party interest in ComEd	1,183,000,000			1,183,000,000			15,000,000
Exelon Generation Co L L C [Member]
Capitalized Interest And AFUDC [Line Items]
Total interest incurred					8,000,000
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Operating and maintenance	1,255,000,000		1,041,000,000	2,194,000,000	2,007,000,000
Interest Expense	74,000,000		77,000,000	147,000,000	142,000,000
Consolidation Percentages Detail Tagging [Abstract]
Equity Method Investment Ownership Percentage	50.01%			50.01%
Third Party interest in ComEd	1,185,000,000			1,185,000,000			17,000,000
Nuclear Fuel [Abstract]
Cost of spent nuclear fuel disposal per kWh of net nuclear generation	0.001			0.001
Commonwealth Edison Co [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Electrical transmission and distribution revenue	1,128,000,000		1,080,000,000	2,261,000,000	2,238,000,000
Operating and maintenance	316,000,000		319,000,000	603,000,000	611,000,000
Interest Expense	76,000,000		72,000,000	153,000,000	422,000,000
PECO Energy Co [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Operating and maintenance	160,000,000		155,000,000	416,000,000	319,000,000
Interest Expense	25,000,000		25,000,000	50,000,000	51,000,000
Baltimore Gas and Electric Company [Member]
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Operating and maintenance	163,000,000		139,000,000	326,000,000	266,000,000
Interest Expense	$ 23,000,000		$ 28,000,000	$ 47,000,000	$ 58,000,000