Quarterly Data (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share Basic [Abstract]
Average common shares outstanding - basic	856	857	856	855	854	854	853	705	856	816	663
Earnings Per Share, Basic	$ 0.60	$ 0.86	$ 0.57	$ (0.01)	$ 0.44	$ 0.35	$ 0.34	$ 0.28
Earnings Per Share Diluted
Average common shares outstanding - diluted	860	860	860	855	857	857	856	707	860	819	665
Earnings Per Share, Diluted	$ 0.59	$ 0.86	$ 0.57	$ (0.01)	$ 0.44	$ 0.35	$ 0.33	$ 0.28	$ 2.00	$ 1.42	$ 3.75
Selected Quarterly Financial Information [Line Items]
Revenues	$ 6,163,000,000	$ 6,502,000,000	$ 6,141,000,000	$ 6,082,000,000	$ 6,254,000,000	$ 6,579,000,000	$ 5,966,000,000	$ 4,690,000,000	$ 24,888,000,000	$ 23,489,000,000	$ 19,063,000,000
Operating Income (Loss)									3,656,000,000	2,380,000,000	4,479,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	495,000,000	738,000,000	490,000,000	(4,000,000)	378,000,000	296,000,000	286,000,000	200,000,000	1,729,000,000	1,171,000,000	2,499,000,000
Operating Income Loss Quarter	889,000,000	1,254,000,000	1,005,000,000	508,000,000	704,000,000	603,000,000	714,000,000	359,000,000
Share Price And Dividend [Abstract]
High Price	30.59	32.42	37.80	34.56	37.50	39.82	39.37	43.70	30.59	37.50
Low Price	26.64	29.42	29.84	29.10	28.40	34.54	36.27	38.31	26.64	28.40
Close	$ 27.39	$ 29.64	$ 30.88	$ 34.48	$ 29.74	$ 35.58	$ 37.62	$ 39.21	$ 27.39	$ 29.74
Dividends	$ 0.310	$ 0.310	$ 0.310	$ 0.525	$ 0.525	$ 0.525	$ 0.525	$ 0.525	$ 0.310	$ 0.525
Exelon Generation Co L L C [Member]
Selected Quarterly Financial Information [Line Items]
Revenues	3,772,000,000	4,255,000,000	4,070,000,000	3,533,000,000	3,898,000,000	4,031,000,000	3,765,000,000	2,743,000,000	15,630,000,000	14,437,000,000	10,447,000,000
Operating Income (Loss)									1,664,000,000	1,120,000,000	2,875,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	269,000,000	490,000,000	330,000,000	(18,000,000)	137,000,000	91,000,000	166,000,000	168,000,000	1,060,000,000	558,000,000	1,771,000,000
Operating Income Loss Quarter	405,000,000	721,000,000	603,000,000	(64,000,000)	290,000,000	174,000,000	384,000,000	272,000,000
Commonwealth Edison Co [Member]
Selected Quarterly Financial Information [Line Items]
Revenues	1,068,000,000	1,156,000,000	1,080,000,000	1,160,000,000	1,290,000,000	1,484,000,000	1,281,000,000	1,388,000,000	4,464,000,000	5,443,000,000	6,056,000,000
Operating Income (Loss)									954,000,000	886,000,000	982,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	109,000,000	126,000,000	96,000,000	(81,000,000)	160,000,000	90,000,000	42,000,000	87,000,000	249,000,000	379,000,000	416,000,000
Operating Income Loss Quarter	236,000,000	278,000,000	232,000,000	209,000,000	300,000,000	218,000,000	142,000,000	226,000,000
PECO Energy Co [Member]
Selected Quarterly Financial Information [Line Items]
Revenues	805,000,000	728,000,000	672,000,000	895,000,000	790,000,000	806,000,000	715,000,000	875,000,000	3,100,000,000	3,186,000,000	3,720,000,000
Operating Income (Loss)									666,000,000	623,000,000	655,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	102,000,000	92,000,000	72,000,000	121,000,000	79,000,000	122,000,000	79,000,000	96,000,000	395,000,000	381,000,000	389,000,000
Operating Income Loss Quarter	168,000,000	155,000,000	138,000,000	203,000,000	117,000,000	178,000,000	151,000,000	177,000,000
Baltimore Gas and Electric Company [Member]
Selected Quarterly Financial Information [Line Items]
Revenues	794,000,000	737,000,000	653,000,000	880,000,000	703,000,000	720,000,000	616,000,000	697,000,000	3,065,000,000	2,735,000,000	3,068,000,000
Operating Income (Loss)									449,000,000	132,000,000	314,000,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	47,000,000	50,000,000	22,000,000	77,000,000	15,000,000	(4,000,000)	13,000,000	(33,000,000)	210,000,000	4,000,000	136,000,000
Operating Income Loss Quarter	$ 101,000,000	$ 114,000,000	$ 69,000,000	$ 163,000,000	$ 61,000,000	$ 30,000,000	$ 52,000,000	$ (11,000,000)