Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Operating revenues [Abstract]
Total operating revenues	$ 6,565,000,000	$ 5,254,000,000	$ 17,205,000,000	$ 14,705,000,000
Operating expenses
Purchased power	3,026,000,000	2,121,000,000	7,398,000,000	5,836,000,000
Operating and maintenance	2,156,000,000	1,413,000,000	5,949,000,000	3,863,000,000
Depreciation and amortization	500,000,000	332,000,000	1,376,000,000	987,000,000
Taxes other than income	290,000,000	207,000,000	737,000,000	602,000,000
Total operating expenses	5,972,000,000	4,073,000,000	15,460,000,000	11,288,000,000
Gain (loss) on equity method investments	10,000,000	0	(69,000,000)	0
Operating income	603,000,000	1,181,000,000	1,676,000,000	3,417,000,000
Other income and deductions
Interest expense	(240,000,000)	(176,000,000)	(678,000,000)	(526,000,000)
Interest expense to affiliates, net	(6,000,000)	(6,000,000)	(19,000,000)	(19,000,000)
Other, net	101,000,000	(142,000,000)	253,000,000	54,000,000
Total other income and deductions	(145,000,000)	(324,000,000)	(444,000,000)	(491,000,000)
Income from continuing operations before income taxes	458,000,000	857,000,000	1,232,000,000	2,926,000,000
Income taxes	161,000,000	255,000,000	445,000,000	1,034,000,000
Net income	297,000,000	602,000,000	787,000,000	1,892,000,000
Net income (loss) attributable to noncontrolling interests and preferred security dividends	(1,000,000)	(1,000,000)	(5,000,000)	(3,000,000)
Net income on common stock	296,000,000	601,000,000	782,000,000	1,889,000,000
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost	0	(1,000,000)	1,000,000	(3,000,000)
Actuarial loss reclassified to periodic cost	44,000,000	33,000,000	126,000,000	100,000,000
Transition obligation reclassified to periodic cost	0	1,000,000	2,000,000	2,000,000
Pension and non-pension postretirement benefit plans valuation adjustment	(67,000,000)	0	(78,000,000)	39,000,000
Change in unrealized gain (loss) on cash-flow hedges	(88,000,000)	(64,000,000)	(29,000,000)	(255,000,000)
Change in unrealized income (loss) on equity investments	17,000,000	0	23,000,000	0
Change in unrealized income (loss) on foriegn currency translation	2,000,000	0	0	0
Change in unrealized gain (loss) on marketable securities	0	0	0	0
Other comprehensive income (loss)	(92,000,000)	(31,000,000)	45,000,000	(117,000,000)
Comprehensive income	205,000,000	571,000,000	832,000,000	1,775,000,000
Average shares of common stock outstanding:
Basic	854,000,000	663,000,000	804,000,000	663,000,000
Diluted	857,000,000	665,000,000	806,000,000	664,000,000
Earnings per average common share - basic
Net income	$ 0.35	$ 0.91	$ 0.97	$ 2.85
Earnings per average common share - diluted
Net income	$ 0.35	$ 0.90	$ 0.97	$ 2.84
Dividends per common share	$ 0.53	$ 0.53	$ 1.58	$ 1.58
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Operating revenues	3,558,000,000	2,517,000,000	9,276,000,000	7,063,000,000
Operating revenues from affiliates	459,000,000	304,000,000	1,233,000,000	856,000,000
Total operating revenues	4,017,000,000	2,821,000,000	10,509,000,000	7,919,000,000
Operating expenses
Purchased power	2,122,000,000	1,071,000,000	5,018,000,000	2,795,000,000
Operating and maintenance	1,289,000,000	713,000,000	3,319,000,000	2,084,000,000
Operating and maintenance from affiliate	126,000,000	77,000,000	437,000,000	222,000,000
Depreciation and amortization	207,000,000	139,000,000	564,000,000	416,000,000
Taxes other than income	109,000,000	67,000,000	272,000,000	199,000,000
Total operating expenses	3,853,000,000	2,067,000,000	9,610,000,000	5,716,000,000
Gain (loss) on equity method investments	10,000,000	0	(69,000,000)	0
Operating income	174,000,000	754,000,000	830,000,000	2,203,000,000
Other income and deductions
Interest expense	(85,000,000)	(37,000,000)	(223,000,000)	(128,000,000)
Other, net	83,000,000	(164,000,000)	185,000,000	(12,000,000)
Total other income and deductions	(2,000,000)	(201,000,000)	(38,000,000)	(140,000,000)
Income from continuing operations before income taxes	172,000,000	553,000,000	792,000,000	2,063,000,000
Income taxes	85,000,000	167,000,000	373,000,000	738,000,000
Net income	87,000,000	386,000,000	419,000,000	1,325,000,000
Income (Loss) attributable to noncontrolling interest	4,000,000		6,000,000
Net income on membership interest	91,000,000	386,000,000	425,000,000	1,325,000,000
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on cash-flow hedges	(171,000,000)	(125,000,000)	(185,000,000)	(448,000,000)
Change in unrealized income (loss) on equity investments	17,000,000		23,000,000
Change in unrealized income (loss) on foriegn currency translation	2,000,000		0
Change in unrealized gain (loss) on marketable securities	0		(1,000,000)
Other comprehensive income (loss)	(152,000,000)	(125,000,000)	(163,000,000)	(448,000,000)
Comprehensive income	(65,000,000)	261,000,000	256,000,000	877,000,000
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues	1,484,000,000	1,783,000,000	4,152,000,000	4,692,000,000
Operating revenues from affiliates	0	1,000,000	2,000,000	2,000,000
Total operating revenues	1,484,000,000	1,784,000,000	4,154,000,000	4,694,000,000
Operating expenses
Purchased power	498,000,000	773,000,000	1,255,000,000	1,986,000,000
Purchased power from affiliate	180,000,000	159,000,000	631,000,000	450,000,000
Operating and maintenance	313,000,000	356,000,000	882,000,000	817,000,000
Operating and maintenance from affiliate	37,000,000	40,000,000	118,000,000	113,000,000
Depreciation and amortization	157,000,000	135,000,000	458,000,000	405,000,000
Taxes other than income	81,000,000	78,000,000	224,000,000	226,000,000
Total operating expenses	1,266,000,000	1,541,000,000	3,568,000,000	3,997,000,000
Operating income	218,000,000	243,000,000	586,000,000	697,000,000
Other income and deductions
Interest expense	(71,000,000)	(82,000,000)	(221,000,000)	(246,000,000)
Interest expense to affiliates, net	(3,000,000)	(4,000,000)	(9,000,000)	(11,000,000)
Other, net	5,000,000	16,000,000	12,000,000	24,000,000
Total other income and deductions	(69,000,000)	(70,000,000)	(218,000,000)	(233,000,000)
Income from continuing operations before income taxes	149,000,000	173,000,000	368,000,000	464,000,000
Income taxes	59,000,000	61,000,000	149,000,000	169,000,000
Net income	90,000,000	112,000,000	219,000,000	295,000,000
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on marketable securities	0	0	1,000,000	0
Other comprehensive income (loss)	0	0	1,000,000	0
Comprehensive income	90,000,000	112,000,000	220,000,000	295,000,000
PECO Energy Co [Member]
Operating revenues [Abstract]
Operating revenues	805,000,000	944,000,000	2,393,000,000	2,938,000,000
Operating revenues from affiliates	1,000,000	2,000,000	3,000,000	4,000,000
Total operating revenues	806,000,000	946,000,000	2,396,000,000	2,942,000,000
Operating expenses
Purchased power	155,000,000	327,000,000	626,000,000	1,112,000,000
Purchased power from affiliate	171,000,000	137,000,000	407,000,000	394,000,000
Operating and maintenance	172,000,000	195,000,000	491,000,000	529,000,000
Operating and maintenance from affiliate	27,000,000	24,000,000	83,000,000	68,000,000
Depreciation and amortization	55,000,000	51,000,000	161,000,000	150,000,000
Taxes other than income	48,000,000	59,000,000	122,000,000	165,000,000
Total operating expenses	628,000,000	793,000,000	1,890,000,000	2,418,000,000
Gain (loss) on equity method investments	0	0	0	0
Operating income	178,000,000	153,000,000	506,000,000	524,000,000
Other income and deductions
Interest expense	(29,000,000)	(31,000,000)	(85,000,000)	(93,000,000)
Interest expense to affiliates, net	(3,000,000)	(3,000,000)	(9,000,000)	(9,000,000)
Other, net	2,000,000	3,000,000	6,000,000	11,000,000
Total other income and deductions	(30,000,000)	(31,000,000)	(88,000,000)	(91,000,000)
Income from continuing operations before income taxes	148,000,000	122,000,000	418,000,000	433,000,000
Income taxes	25,000,000	17,000,000	118,000,000	119,000,000
Net income	123,000,000	105,000,000	300,000,000	314,000,000
Preferred security dividends	(1,000,000)	(1,000,000)	(3,000,000)	(3,000,000)
Net income on common stock	122,000,000	104,000,000	297,000,000	311,000,000
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on marketable securities	0	0	1,000,000	0
Other comprehensive income (loss)	0	0	1,000,000	0
Comprehensive income	123,000,000	105,000,000	301,000,000	314,000,000
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Operating revenues	716,000,000	742,000,000	2,023,000,000	2,388,000,000
Operating revenues from affiliates	4,000,000	3,000,000	9,000,000	6,000,000
Total operating revenues	720,000,000	745,000,000	2,032,000,000	2,394,000,000
Operating expenses
Purchased power and fuel	253,000,000	268,000,000	747,000,000	1,021,000,000
Purchased power and fuel from affiliate	120,000,000	137,000,000	296,000,000	267,000,000
Operating and maintenance	172,000,000	184,000,000	460,000,000	433,000,000
Operating and maintenance from affiliate	29,000,000	26,000,000	97,000,000	96,000,000
Depreciation and amortization	68,000,000	60,000,000	218,000,000	205,000,000
Taxes other than income	48,000,000	47,000,000	143,000,000	143,000,000
Total operating expenses	690,000,000	722,000,000	1,961,000,000	2,165,000,000
Operating income	30,000,000	23,000,000	71,000,000	229,000,000
Other income and deductions
Interest expense	(35,000,000)	(32,000,000)	(110,000,000)	(97,000,000)
Interest expense to affiliates, net	0	0	0	0
Other, net	5,000,000	8,000,000	18,000,000	22,000,000
Total other income and deductions	(30,000,000)	(24,000,000)	(92,000,000)	(75,000,000)
Income from continuing operations before income taxes	0	(1,000,000)	(21,000,000)	154,000,000
Income taxes	0	(3,000,000)	(7,000,000)	55,000,000
Net income	0	2,000,000	(14,000,000)	99,000,000
Preferred security dividends	(4,000,000)	(4,000,000)	(10,000,000)	(10,000,000)
Net income on common stock	(4,000,000)	(2,000,000)	(24,000,000)	89,000,000
Pension and non-pension postretirement benefit plans:
Comprehensive income	$ 0	$ 2,000,000	$ (14,000,000)	$ 99,000,000