Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Operating revenues [Abstract]
Total operating revenues	$ 5,954,000,000	$ 4,496,000,000	$ 10,640,000,000	$ 9,451,000,000
Operating expenses
Purchased power	2,606,000,000	1,716,000,000	4,371,000,000	3,716,000,000
Operating and maintenance	1,829,000,000	1,226,000,000	3,793,000,000	2,449,000,000
Depreciation and amortization	494,000,000	329,000,000	876,000,000	656,000,000
Taxes other than income	254,000,000	191,000,000	448,000,000	394,000,000
Total operating expenses	5,183,000,000	3,462,000,000	9,488,000,000	7,215,000,000
Gain (loss) on equity method investments	(57,000,000)	0	(79,000,000)	0
Operating income	714,000,000	1,034,000,000	1,073,000,000	2,236,000,000
Other income and deductions
Interest expense	(250,000,000)	(176,000,000)	(439,000,000)	(350,000,000)
Interest expense to affiliates, net	(6,000,000)	(6,000,000)	(12,000,000)	(13,000,000)
Other, net	(43,000,000)	101,000,000	152,000,000	196,000,000
Total other income and deductions	(299,000,000)	(81,000,000)	(299,000,000)	(167,000,000)
Income from continuing operations before income taxes	415,000,000	953,000,000	774,000,000	2,069,000,000
Income taxes	126,000,000	332,000,000	284,000,000	779,000,000
Net income	289,000,000	621,000,000	490,000,000	1,290,000,000
Net income (loss) attributable to noncontrolling interests and preferred security dividends	(3,000,000)	(1,000,000)	(4,000,000)	(2,000,000)
Net income on common stock	286,000,000	620,000,000	486,000,000	1,288,000,000
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost	1,000,000	(1,000,000)	1,000,000	(2,000,000)
Actuarial loss reclassified to periodic cost	41,000,000	34,000,000	82,000,000	66,000,000
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	(3,000,000)	0	(11,000,000)	39,000,000
Change in unrealized gain (loss) on cash-flow hedges	(156,000,000)	(145,000,000)	59,000,000	(191,000,000)
Amortization of realized loss on settled cash flow swaps	6,000,000	0	6,000,000	0
Change in unrealized income (loss) on foriegn currency translation	(2,000,000)	0	(2,000,000)	0
Change in unrealized gain (loss) on marketable securities	(1,000,000)	0	0	0
Other comprehensive income (loss)	(114,000,000)	(111,000,000)	137,000,000	(86,000,000)
Comprehensive income	175,000,000	510,000,000	627,000,000	1,204,000,000
Average shares of common stock outstanding:
Basic	853,000,000	663,000,000	779,000,000	663,000,000
Diluted	856,000,000	664,000,000	781,000,000	664,000,000
Earnings per average common share - basic
Net income	$ 0.34	$ 0.93	$ 0.62	$ 1.94
Earnings per average common share - diluted
Net income	$ 0.33	$ 0.93	$ 0.62	$ 1.94
Dividends per common share	$ 0.53	$ 0.53	$ 1.05	$ 1.05
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Operating revenues	3,345,000,000	2,209,000,000	5,718,000,000	4,546,000,000
Operating revenues from affiliates	408,000,000	246,000,000	774,000,000	552,000,000
Total operating revenues	3,753,000,000	2,455,000,000	6,492,000,000	5,098,000,000
Operating expenses
Purchased power	1,852,000,000	841,000,000	2,896,000,000	1,724,000,000
Operating and maintenance	990,000,000	692,000,000	2,029,000,000	1,372,000,000
Operating and maintenance from affiliate	176,000,000	71,000,000	311,000,000	145,000,000
Depreciation and amortization	204,000,000	138,000,000	357,000,000	277,000,000
Taxes other than income	90,000,000	66,000,000	164,000,000	132,000,000
Total operating expenses	3,312,000,000	1,808,000,000	5,757,000,000	3,650,000,000
Gain (loss) on equity method investments	(57,000,000)	0	(79,000,000)	0
Operating income	384,000,000	647,000,000	656,000,000	1,448,000,000
Other income and deductions
Interest expense	(85,000,000)	(45,000,000)	(138,000,000)	(91,000,000)
Other, net	(76,000,000)	76,000,000	103,000,000	152,000,000
Total other income and deductions	(161,000,000)	31,000,000	(35,000,000)	61,000,000
Income from continuing operations before income taxes	223,000,000	678,000,000	621,000,000	1,509,000,000
Income taxes	58,000,000	235,000,000	289,000,000	571,000,000
Net income	165,000,000	443,000,000	332,000,000	938,000,000
Income (Loss) attributable to noncontrolling interest	1,000,000		2,000,000
Net income on membership interest	166,000,000	443,000,000	334,000,000	938,000,000
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on cash-flow hedges	(266,000,000)	(254,000,000)	(14,000,000)	(323,000,000)
Amortization of realized loss on settled cash flow swaps	6,000,000		6,000,000
Change in unrealized income (loss) on foriegn currency translation	(2,000,000)		(2,000,000)
Change in unrealized gain (loss) on marketable securities	(1,000,000)		(1,000,000)
Other comprehensive income (loss)	(263,000,000)	(254,000,000)	(11,000,000)	(323,000,000)
Comprehensive income	(98,000,000)	189,000,000	321,000,000	615,000,000
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues	1,280,000,000	1,444,000,000	2,669,000,000	2,909,000,000
Operating revenues from affiliates	1,000,000	0	1,000,000	1,000,000
Total operating revenues	1,281,000,000	1,444,000,000	2,670,000,000	2,910,000,000
Operating expenses
Purchased power	384,000,000	588,000,000	757,000,000	1,214,000,000
Purchased power from affiliate	203,000,000	128,000,000	451,000,000	291,000,000
Operating and maintenance	293,000,000	232,000,000	569,000,000	461,000,000
Operating and maintenance from affiliate	38,000,000	36,000,000	81,000,000	73,000,000
Depreciation and amortization	152,000,000	136,000,000	300,000,000	270,000,000
Taxes other than income	69,000,000	70,000,000	144,000,000	147,000,000
Total operating expenses	1,139,000,000	1,190,000,000	2,302,000,000	2,456,000,000
Operating income	142,000,000	254,000,000	368,000,000	454,000,000
Other income and deductions
Interest expense	(71,000,000)	(82,000,000)	(150,000,000)	(164,000,000)
Interest expense to affiliates, net	(3,000,000)	(4,000,000)	(6,000,000)	(8,000,000)
Other, net	3,000,000	4,000,000	7,000,000	8,000,000
Total other income and deductions	(71,000,000)	(82,000,000)	(149,000,000)	(164,000,000)
Income from continuing operations before income taxes	71,000,000	172,000,000	219,000,000	290,000,000
Income taxes	29,000,000	58,000,000	90,000,000	107,000,000
Net income	42,000,000	114,000,000	129,000,000	183,000,000
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	42,000,000	114,000,000	130,000,000	183,000,000
PECO Energy Co [Member]
Operating revenues [Abstract]
Operating revenues	714,000,000	842,000,000	1,588,000,000	1,994,000,000
Operating revenues from affiliates	1,000,000	0	2,000,000	2,000,000
Total operating revenues	715,000,000	842,000,000	1,590,000,000	1,996,000,000
Operating expenses
Purchased power	171,000,000	293,000,000	472,000,000	785,000,000
Purchased power from affiliate	125,000,000	115,000,000	235,000,000	257,000,000
Operating and maintenance	146,000,000	150,000,000	318,000,000	334,000,000
Operating and maintenance from affiliate	26,000,000	22,000,000	57,000,000	44,000,000
Operating and maintenance for regulatory required programs	0	0	0	0
Depreciation and amortization	54,000,000	50,000,000	107,000,000	98,000,000
Taxes other than income	42,000,000	51,000,000	74,000,000	106,000,000
Total operating expenses	564,000,000	681,000,000	1,263,000,000	1,624,000,000
Gain (loss) on equity method investments	0	0	0	0
Operating income	151,000,000	161,000,000	327,000,000	372,000,000
Other income and deductions
Interest expense	(28,000,000)	(31,000,000)	(56,000,000)	(62,000,000)
Interest expense to affiliates, net	(3,000,000)	(3,000,000)	(6,000,000)	(6,000,000)
Other, net	2,000,000	3,000,000	5,000,000	8,000,000
Total other income and deductions	(29,000,000)	(31,000,000)	(57,000,000)	(60,000,000)
Income from continuing operations before income taxes	122,000,000	130,000,000	270,000,000	312,000,000
Income taxes	42,000,000	47,000,000	93,000,000	102,000,000
Net income	80,000,000	83,000,000	177,000,000	210,000,000
Preferred security dividends	(1,000,000)	(1,000,000)	(2,000,000)	(2,000,000)
Net income on common stock	79,000,000	82,000,000	175,000,000	208,000,000
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	80,000,000	83,000,000	178,000,000	210,000,000
Baltimore Gas and Electric Company [Member]
Operating revenues [Abstract]
Operating revenues	614,000,000	672,000,000	1,307,000,000	1,647,000,000
Operating revenues from affiliates	2,000,000	2,000,000	5,000,000	3,000,000
Total operating revenues	616,000,000	674,000,000	1,312,000,000	1,650,000,000
Operating expenses
Purchased power and fuel	201,000,000	267,000,000	494,000,000	753,000,000
Purchased power and fuel from affiliate	84,000,000	73,000,000	176,000,000	130,000,000
Operating and maintenance	135,000,000	129,000,000	288,000,000	249,000,000
Operating and maintenance from affiliate	26,000,000	38,000,000	68,000,000	70,000,000
Depreciation and amortization	71,000,000	67,000,000	150,000,000	144,000,000
Taxes other than income	47,000,000	46,000,000	95,000,000	96,000,000
Total operating expenses	564,000,000	620,000,000	1,271,000,000	1,442,000,000
Operating income	52,000,000	54,000,000	41,000,000	208,000,000
Other income and deductions
Interest expense	(34,000,000)	(32,000,000)	(75,000,000)	(66,000,000)
Interest expense to affiliates, net	0	0	0	0
Other, net	7,000,000	6,000,000	13,000,000	13,000,000
Total other income and deductions	(27,000,000)	(26,000,000)	(62,000,000)	(53,000,000)
Income from continuing operations before income taxes	25,000,000	28,000,000	(21,000,000)	155,000,000
Income taxes	9,000,000	12,000,000	(7,000,000)	58,000,000
Net income	16,000,000	16,000,000	(14,000,000)	97,000,000
Preferred security dividends	(3,000,000)	(3,000,000)	(6,000,000)	(6,000,000)
Net income on common stock	13,000,000	13,000,000	(20,000,000)	91,000,000
Pension and non-pension postretirement benefit plans:
Comprehensive income	$ 16,000,000	$ 16,000,000	$ (14,000,000)	$ 97,000,000