Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Millions, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Operating revenues [Abstract]
Total operating revenues	$ 5,295	$ 5,291	$ 14,933	$ 14,150
Operating expenses
Purchased power	1,711	1,481	4,602	3,273
Fuel	451	475	1,462	1,469
Operating and maintenance	1,354	1,122	3,725	3,298
Operating and maintenance for regulatory required programs	59	37	138	98
Depreciation and amortization	332	578	987	1,611
Taxes other than income	207	232	602	615
Total operating expenses	4,114	3,925	11,516	10,364
Operating income	1,181	1,366	3,417	3,786
Other income and deductions
Interest expense, net	(176)	(169)	(526)	(615)
Interest expense to affiliates, net	(6)	(6)	(19)	(19)
Loss in equity method investments	0	0	0	0
Other, net	(143)	206	51	178
Total other income and deductions	(325)	31	(494)	(456)
Income from continuing operations before income taxes	856	1,397	2,923	3,330
Income taxes	255	552	1,034	1,291
Net income	601	845	1,889	2,039
Pension and non-pension postretirement benefit plans:
Prior service benefit reclassified to periodic benefit cost	(1)	3	(3)	(8)
Actuarial loss reclassified to periodic cost	33	24	100	86
Transition obligation reclassified to periodic cost	1	0	2	5
Pension and non-pension postretirement benefit plans valuation adjustment	0	2	39	(18)
Change in unrealized gain (loss) on cash-flow hedges	(64)	222	(255)	196
Change in unrealized gain (loss) on marketable securities	0	0	0	0
Other comprehensive income (loss)	(31)	251	(117)	261
Comprehensive income	570	1,096	1,772	2,300
Average shares of common stock outstanding:
Basic	663	662	663	661
Diluted	665	663	664	662
Earnings per average common share - basic
Net income	$ 0.91	$ 1.28	$ 2.85	$ 3.08
Earnings per average common share - diluted
Net income	$ 0.90	$ 1.27	$ 2.84	$ 3.08
Dividends per common share	$ 0.53	$ 0.53	$ 1.58	$ 1.58
Exelon Generation Co L L C [Member]
Operating revenues [Abstract]
Operating revenues	2,558	1,877	7,291	5,098
Operating revenues from affiliates	304	778	856	2,330
Total operating revenues	2,862	2,655	8,147	7,428
Operating expenses
Purchased power	680	494	1,801	1,251
Fuel	432	451	1,222	1,191
Operating and maintenance	713	580	2,084	1,865
Operating and maintenance from affiliate	77	69	222	216
Depreciation and amortization	139	121	416	344
Taxes other than income	67	57	199	175
Total operating expenses	2,108	1,772	5,944	5,042
Operating income	754	883	2,203	2,386
Other income and deductions
Interest expense, net	(37)	(37)	(128)	(109)
Loss in equity method investments	0	0	0	0
Other, net	(164)	192	(12)	138
Total other income and deductions	(201)	155	(140)	29
Income from continuing operations before income taxes	553	1,038	2,063	2,415
Income taxes	167	433	738	867
Net income	386	605	1,325	1,548
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on cash-flow hedges	(125)	292	(448)	298
Other comprehensive income (loss)	(125)	292	(448)	298
Comprehensive income	261	897	877	1,846
Commonwealth Edison Co [Member]
Operating revenues [Abstract]
Operating revenues	1,783	1,918	4,692	4,831
Operating revenues from affiliates	1	0	2	1
Total operating revenues	1,784	1,918	4,694	4,832
Operating expenses
Purchased power	773	910	1,986	1,810
Purchased power from affiliate	159	202	450	826
Operating and maintenance	313	260	733	620
Operating and maintenance from affiliate	40	38	113	113
Operating and maintenance for regulatory required programs	43	22	84	62
Depreciation and amortization	135	126	405	386
Taxes other than income	78	81	226	188
Total operating expenses	1,541	1,639	3,997	4,005
Operating income	243	279	697	827
Other income and deductions
Interest expense, net	(82)	(79)	(246)	(290)
Interest expense to affiliates, net	(4)	(3)	(11)	(10)
Other, net	16	3	24	14
Total other income and deductions	(70)	(79)	(233)	(286)
Income from continuing operations before income taxes	173	200	464	541
Income taxes	61	79	169	295
Net income	112	121	295	246
Pension and non-pension postretirement benefit plans:
Change in unrealized gain (loss) on cash-flow hedges	0	4	0	0
Change in unrealized gain (loss) on marketable securities	0	0	0	0
Other comprehensive income (loss)	0	4	0	0
Comprehensive income	112	125	295	246
PECO Energy Co [Member]
Operating revenues [Abstract]
Operating revenues	944	1,494	2,938	4,216
Operating revenues from affiliates	2	1	4	4
Total operating revenues	946	1,495	2,942	4,220
Operating expenses
Purchased power	308	76	871	211
Purchased power from affiliate	137	574	394	1,498
Fuel	19	23	241	278
Operating and maintenance	179	155	475	440
Operating and maintenance from affiliate	24	21	68	67
Operating and maintenance for regulatory required programs	16	15	54	36
Depreciation and amortization	51	326	150	859
Taxes other than income	59	90	165	240
Total operating expenses	793	1,280	2,418	3,629
Operating income	153	215	524	591
Other income and deductions
Interest expense, net	(31)	(35)	(93)	(151)
Interest expense to affiliates, net	(3)	(3)	(9)	(9)
Loss in equity method investments	0	0	0	0
Other, net	3	3	11	6
Total other income and deductions	(31)	(35)	(91)	(154)
Income from continuing operations before income taxes	122	180	433	437
Income taxes	17	53	119	134
Net income	105	127	314	303
Preferred security dividends	1	1	3	3
Net income on common stock	104	126	311	300
Pension and non-pension postretirement benefit plans:
Amortization of realized loss on settled cash flow swaps	0	0	0	(1)
Change in unrealized gain (loss) on marketable securities	0	0	0	0
Other comprehensive income (loss)	0	0	0	(1)
Comprehensive income	$ 105	$ 127	$ 314	$ 302