Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 1,600		$ 1,411
Cash and cash equivalents of variable interest entities	44		75
Restricted cash and investments	60		86
Restricted cash and investments of variable interest entity	87		47
Accounts receivable, net
Customer	2,584		2,795
Other	1,232		1,141
Accounts receivable of variable interest entities	177		292
Mark-to-market derivative assets	730		938
Unamortized energy contracts assets	460		886
Inventories, net
Fossil fuel	288		246
Materials and supplies	821		768
Deferred income taxes	292		131
Regulatory assets	877		764
Other	699		560
Total current assets	9,951		10,140
Property, plant and equipment, net	46,495		45,186
Deferred debits and other assets
Regulatory assets	6,509		6,497
Nuclear decommissioning trust funds	7,776		7,248
Investments	1,154		1,184
Investments in affiliates	23		22
Investment in CENG	1,939		1,849
Goodwill	2,625		2,625
Mark-to-market derivative assets	779		937
Pledged assets for Zion Station decommissioning	486		614
Unamortized energy contracts assets	803		1,073
Other	1,121		1,186
Deferred income taxes			116
Total deferred debits and other assets	23,215		23,235
Total assets	79,661		78,561
Current liabilities
Short-term borrowings	214		0
Short-term notes payable - accounts receivable agreement	0		210
Long-term debt due within one year	1,461		975
Long-term debt of variable interest entities due within one year	182		72
Accounts payable	2,369		2,446
Accounts payable of variable interest entities	108		202
Accrued expenses	1,540		1,800
Deferred income taxes	50		58
Regulatory liabilities	314		368
Mark-to-market derivative liabilities	126		352
Unamortized energy contract liabilities	305		455
Other	838		853
Total current liabilities	7,507		7,791
Long-term debt	17,583		17,190
Long-term debt of variable financing trusts	648		648
Long-term debt of variable interest entity	339		508
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	11,931		11,551
Asset retirement obligations	5,118		5,074
Pension obligations	3,094		3,428
Non-pension postretirement benefit obligations	2,764		2,662
Spent nuclear fuel obligation	1,021		1,020
Regulatory liabilities	4,204		3,981
Mark-to-market derivative liabilities	218		281
Unamortized energy contract liabilities	314		528
Payable for Zion Station decommissioning	339		432
Other	2,514		1,650
Total deferred credits and other liabilities	31,517		30,607
Total liabilities	57,594		56,744
Commitments and contingencies
Preferred securities	0		87
Shareholders' equity
Common stock	16,716		16,632
Treasury stock, at cost (35 and 35 shares held at December 31, 2010 and December 31, 2009, respectively)	(2,327)		(2,327)
Retained earnings	10,131		9,893
Accumulated other comprehensive income (loss), net	(2,661)	[1]	(2,767)	[1]
Total shareholders' equity	21,859		21,431
BGE preference stock not subject to mandatory redemption	193		193
Noncontrolling interest	15		106
Total equity	22,067		21,730
Total liabilities and shareholders' equity	79,661		78,561
Member's equity
Accumulated other comprehensive income (loss), net	(2,661)	[1]	(2,767)	[1]
Removal Costs [Member]
Current liabilities
Regulatory liabilities	103		97
Deferred credits and other liabilities
Regulatory liabilities	1,420		1,406
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	884		596
Cash and cash equivalents of variable interest entities	44		75
Restricted cash and cash equivalents	0		0
Restricted cash and investments of variable interest entity	37		16
Accounts receivable, net
Customer	1,489		1,482
Other	417		472
Accounts receivable of variable interest entities	175		292
Mark-to-market derivative assets	730		938
Mark-to-market derivative assets with affiliates	0		226
Receivables from affiliates	107		141
Unamortized energy contracts assets	460		886
Inventories, net
Fossil fuel	169		130
Materials and supplies	661		626
Deferred income taxes	177
Other	455		331
Total current assets	5,805		6,211
Property, plant and equipment, net	19,797		19,531
Deferred debits and other assets
Nuclear decommissioning trust funds	7,776		7,248
Investments	401		420
Investments in affiliates	0		0
Investment in CENG	1,939		1,849
Mark-to-market derivative assets	766		924
Prepaid pension asset	1,927		1,975
Pledged assets for Zion Station decommissioning	486		614
Unamortized energy contracts assets	803		1,073
Other	798		836
Total deferred debits and other assets	14,896		14,939
Total assets	40,498		40,681
Current liabilities
Short-term borrowings	21		0
Long-term debt due within one year	544		24
Long-term debt of variable interest entities due within one year	104		4
Accounts payable	1,254		1,346
Accounts payable of variable interest entities	108		202
Accrued expenses	925		1,116
Payables to affiliates	162		193
Borrowings from Exelon intercompany money pool	0
Deferred income taxes	44		128
Mark-to-market derivative liabilities	110		334
Unamortized energy contract liabilities	276		378
Other	348		372
Total current liabilities	3,896		4,097
Long-term debt	5,545		5,245
Long-term debt to affiliate	1,528		2,007
Long-term debt of variable interest entity	88		203
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	5,899		5,398
Asset retirement obligations	4,983		4,938
Non-pension postretirement benefit obligations	843		755
Spent nuclear fuel obligation	1,021		1,020
Payables to affiliates	2,593		2,397
Mark-to-market derivative liabilities	112		232
Unamortized energy contract liabilities	311		516
Payable for Zion Station decommissioning	339		432
Other	789		776
Total deferred credits and other liabilities	16,890		16,464
Total liabilities	27,947		28,016
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	243	[1]	513	[1]
Noncontrolling interest	17		108
Member's equity
Membership interest	8,872		8,876
Undistributed earnings	3,419		3,168
Accumulated other comprehensive income (loss), net	243	[1]	513	[1]
Total member's equity	12,534		12,557
Total equity	12,551		12,665
Total liabilities and equity	40,498		40,681
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	34		144
Restricted cash and cash equivalents	3		0
Accounts receivable, net
Customer	443		539
Other	525		452
Inventories, net
Inventories, net	103		91
Deferred income taxes	18		83
Receivable from Exelon intercompany money pool	172
Counterparty collateral deposited	3		53
Regulatory assets	335		388
Other	31		25
Total current assets	1,495		1,775
Property, plant and equipment, net	14,444		13,826
Deferred debits and other assets
Regulatory assets	819		666
Investments	5		8
Investments in affiliates	6		6
Goodwill	2,625		2,625
Receivable from affiliate	2,361		2,039
Prepaid pension asset	1,631		1,661
Other	300		299
Total deferred debits and other assets	7,747		7,304
Total assets	23,686		22,905
Current liabilities
Short-term borrowings	153		0
Long-term debt due within one year	617		252
Accounts payable	474		379
Accrued expenses	238		295
Payables to affiliates	61		97
Customer deposits	133		136
Regulatory liabilities	171		170
Mark-to-market derivative liabilities	16		18
Mark-to-market derivative liabilities with affiliate	0		226
Other	84		82
Total current liabilities	1,947		1,655
Long-term debt	5,057		5,315
Long-term debt of variable financing trusts	206		206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,057		4,272
Asset retirement obligations	99		99
Non-pension postretirement benefit obligations	354		273
Regulatory liabilities	3,393		3,229
Mark-to-market derivative liabilities	106		49
Other	994		484
Total deferred credits and other liabilities	9,003		8,406
Total liabilities	16,213		15,582
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,588		1,588
Other paid-in capital	5,189		5,014
Retained earnings	696		721
Accumulated other comprehensive income (loss), net	0		0
Total shareholders' equity	7,473		7,323
Total liabilities and shareholders' equity	23,686		22,905
Member's equity
Accumulated other comprehensive income (loss), net	0		0
Commonwealth Edison Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	82		75
Deferred credits and other liabilities
Regulatory liabilities	1,202		1,192
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	609		362
Restricted cash and cash equivalents	1
Accounts receivable, net
Customer	250		364
Other	116		161
Inventories, net
Fossil fuel	58		65
Materials and supplies	21		19
Deferred income taxes	48		40
Receivable from Exelon intercompany money pool	1
Prepaid utility taxes	38		21
Regulatory assets	22		32
Other	46		30
Total current assets	1,210		1,094
Property, plant and equipment, net	6,270		6,078
Deferred debits and other assets
Regulatory assets	1,419		1,378
Investments	22		22
Investments in affiliates	8		8
Receivable from affiliate	410		360
Prepaid pension asset	368		373
Other	38		40
Total deferred debits and other assets	2,265		2,181
Total assets	9,745		9,353
Current liabilities
Short-term notes payable - accounts receivable agreement			210
Long-term debt due within one year	300		300
Accounts payable	249		244
Accrued expenses	91		82
Payables to affiliates	51		76
Customer deposits	49		51
Regulatory liabilities	111		169
Other	28		26
Total current liabilities	879		1,158
Long-term debt	2,196		1,647
Long-term debt of variable financing trusts	184		184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,440		2,331
Asset retirement obligations	29		29
Non-pension postretirement benefit obligations	301		284
Regulatory liabilities	592		538
Other	105		113
Total deferred credits and other liabilities	3,467		3,295
Total liabilities	6,726		6,284
Preferred securities			87
Shareholders' equity
Common stock	2,388		2,388
Retained earnings	630		593
Accumulated other comprehensive income (loss), net	1	[1]	1	[1]
Total shareholders' equity	3,019		2,982
Total liabilities and shareholders' equity	9,745		9,353
Member's equity
Accumulated other comprehensive income (loss), net	1	[1]	1	[1]
PECO Energy Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities			0
Deferred credits and other liabilities
Regulatory liabilities			0
Baltimore Gas and Electric Company [Member]
Current assets
Cash and cash equivalents	7		89
Restricted cash and cash equivalents	0
Restricted cash and investments of variable interest entity	50		30
Accounts receivable, net
Customer	404		409
Other	132		111
Income taxes receivable	0		3
Inventories, net
Fossil fuel	61		51
Materials and supplies	36		31
Deferred income taxes	5		1
Prepaid utility taxes	76		57
Regulatory assets	184		190
Other	7		8
Total current assets	962		980
Property, plant and equipment, net	5,713		5,498
Deferred debits and other assets
Regulatory assets	509		522
Investments	5		5
Investments in affiliates	8		8
Prepaid pension asset	434		467
Other	26		26
Total deferred debits and other assets	982		1,028
Total assets	7,657		7,506
Current liabilities
Short-term borrowings	40		0
Long-term debt due within one year	0		400
Long-term debt of variable interest entities due within one year	69		67
Accounts payable	184		195
Accrued expenses	127		106
Payables to affiliates	54		65
Deferred income taxes	9		0
Customer deposits	72		71
Regulatory liabilities	31		29
Other	58		47
Total current liabilities	644		980
Long-term debt	1,746		1,446
Long-term debt of variable financing trusts	258		258
Long-term debt of variable interest entity	230		265
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,759		1,658
Asset retirement obligations	7		8
Non-pension postretirement benefit obligations	221		229
Regulatory liabilities	218		214
Other	66		90
Total deferred credits and other liabilities	2,271		2,199
Total liabilities	5,149		5,148
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,360		1,360
Retained earnings	958		808
Total shareholders' equity	2,318		2,168
BGE preference stock not subject to mandatory redemption	190		190
Total equity	2,508		2,358
Total liabilities and shareholders' equity	7,657		7,506
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	21		22
Deferred credits and other liabilities
Regulatory liabilities	$ 218		$ 214

[1] (a) All amounts are net of tax. Amounts in parenthesis represent a decrease in accumulated other comprehensive income.