Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 956		$ 1,411
Cash and cash equivalents of variable interest entities	35		75
Restricted cash and investments	61		86
Restricted cash and investments of variable interest entity	53		47
Accounts receivable, net
Customer	2,609		2,795
Other	1,224		1,141
Accounts receivable of variable interest entities	252		292
Mark-to-market derivative assets	845		938
Mark-to-market derivative assets with affiliates			(226)	[1]
Unamortized energy contracts assets	573		886
Inventories, net
Fossil fuel	214		246
Materials and supplies	805		768
Deferred income taxes	288		131
Regulatory assets	804		764
Other	690		560
Total current assets	9,409		10,140
Property, plant and equipment, net	45,994		45,186
Deferred debits and other assets
Regulatory assets	6,519		6,497
Nuclear decommissioning trust funds	7,463		7,248
Investments	1,171		1,184
Investments in affiliates	22		22
Investment in CENG	1,876		1,849
Goodwill	2,625		2,625
Mark-to-market derivative assets	772		937
Pledged assets for Zion Station decommissioning	538		614
Unamortized energy contracts assets	856		1,073
Other	1,175		1,186
Deferred income taxes			116
Total deferred debits and other assets	23,017		23,235
Total assets	78,420		78,561
Current liabilities
Short-term borrowings	662		0
Short-term notes payable - accounts receivable agreement	210		210
Long-term debt due within one year	1,944		975
Long-term debt of variable interest entities due within one year	87		72
Accounts payable	2,210		2,446
Accounts payable of variable interest entities	147		202
Accrued expenses	1,382		1,800
Deferred income taxes	45		58
Regulatory liabilities	357		368
Mark-to-market derivative liabilities	147		352
Unamortized energy contract liabilities	360		455
Other	823		853
Total current liabilities	8,374		7,791
Long-term debt	16,121		17,190
Long-term debt of variable financing trusts	648		648
Long-term debt of variable interest entity	449		508
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	11,519		11,551
Asset retirement obligations	5,202		5,074
Pension obligations	3,164		3,428
Non-pension postretirement benefit obligations	2,706		2,662
Spent nuclear fuel obligation	1,020		1,020
Regulatory liabilities	4,044		3,981
Mark-to-market derivative liabilities	178		281
Unamortized energy contract liabilities	399		528
Payable for Zion Station decommissioning	373		432
Other	2,635		1,650
Total deferred credits and other liabilities	31,240		30,607
Total liabilities	56,832		56,744
Commitments and contingencies
Preferred securities	0		87
Shareholders' equity
Common stock	16,693		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	9,660		9,893
Accumulated other comprehensive income (loss), net	(2,673)	[2]	(2,767)	[2]
Total shareholders' equity	21,353		21,431
BGE preference stock not subject to mandatory redemption	193		193
Noncontrolling interest	42		106
Total equity	21,588		21,730
Total liabilities and shareholders' equity	78,420		78,561
Member's equity
Accumulated other comprehensive income (loss), net	(2,673)	[2]	(2,767)	[2]
Noncontrolling interest	42		106
Removal Costs [Member]
Current liabilities
Regulatory liabilities	99		97
Deferred credits and other liabilities
Regulatory liabilities	1,422		1,406
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	187		596
Cash and cash equivalents of variable interest entities	35		75
Restricted cash and cash equivalents	0		0
Restricted cash and investments of variable interest entity	27		16
Accounts receivable, net
Customer	1,464		1,482
Other	347		472
Accounts receivable of variable interest entities	242		292
Mark-to-market derivative assets	845		938
Mark-to-market derivative assets with affiliates	0		226
Receivables from affiliates	123		141
Unamortized energy contracts assets	573		886
Inventories, net
Fossil fuel	133		130
Materials and supplies	648		626
Deferred income taxes	195
Other	488		331
Total current assets	5,307		6,211
Property, plant and equipment, net	19,678		19,531
Deferred debits and other assets
Nuclear decommissioning trust funds	7,463		7,248
Investments	409		420
Investments in affiliates	0		0
Investment in CENG	1,876		1,849
Mark-to-market derivative assets	740		924
Prepaid pension asset	1,982		1,975
Pledged assets for Zion Station decommissioning	538		614
Unamortized energy contracts assets	856		1,073
Other	829		836
Total deferred debits and other assets	14,693		14,939
Total assets	39,678		40,681
Current liabilities
Short-term borrowings	288		0
Long-term debt due within one year	500		24
Long-term debt of variable interest entities due within one year	8		4
Accounts payable	1,134		1,346
Accounts payable of variable interest entities	147		202
Accrued expenses	812		1,116
Payables to affiliates	148		193
Borrowings from Exelon intercompany money pool	263
Deferred income taxes	35		128
Mark-to-market derivative liabilities	131		334
Unamortized energy contract liabilities	315		378
Other	321		372
Total current liabilities	4,102		4,097
Long-term debt	4,975		5,245
Long-term debt to affiliate	1,534		2,007
Long-term debt of variable interest entity	196		203
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	5,647		5,398
Asset retirement obligations	5,065		4,938
Non-pension postretirement benefit obligations	814		755
Spent nuclear fuel obligation	1,020		1,020
Payables to affiliates	2,433		2,397
Mark-to-market derivative liabilities	109		232
Unamortized energy contract liabilities	393		516
Payable for Zion Station decommissioning	373		432
Other	820		776
Total deferred credits and other liabilities	16,674		16,464
Total liabilities	27,481		28,016
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	275	[2]	513	[2]
Noncontrolling interest	44		108
Member's equity
Membership interest	8,873		8,876
Undistributed earnings	3,005		3,168
Accumulated other comprehensive income (loss), net	275	[2]	513	[2]
Total member's equity	12,153		12,557
Noncontrolling interest	44		108
Total equity	12,197		12,665
Total liabilities and equity	39,678		40,681
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	93		144
Restricted cash and cash equivalents	3		0
Accounts receivable, net
Customer	455		539
Other	518		452
Inventories, net
Inventories, net	102		91
Deferred income taxes	32		83
Counterparty collateral deposited	8		53
Regulatory assets	274		388
Other	26		25
Total current assets	1,511		1,775
Property, plant and equipment, net	14,233		13,826
Deferred debits and other assets
Regulatory assets	732		666
Investments	6		8
Investments in affiliates	6		6
Goodwill	2,625		2,625
Receivable from affiliate	2,244		2,039
Prepaid pension asset	1,680		1,661
Other	312		299
Total deferred debits and other assets	7,605		7,304
Total assets	23,349		22,905
Current liabilities
Short-term borrowings	374		0
Long-term debt due within one year	744		252
Accounts payable	432		379
Accrued expenses	253		295
Payables to affiliates	70		97
Customer deposits	135		136
Regulatory liabilities	151		170
Mark-to-market derivative liabilities	16		18
Mark-to-market derivative liabilities with affiliate	0		226
Other	81		82
Total current liabilities	2,256		1,655
Long-term debt	4,707		5,315
Long-term debt of variable financing trusts	206		206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	3,997		4,272
Asset retirement obligations	100		99
Non-pension postretirement benefit obligations	327		273
Regulatory liabilities	3,276		3,229
Mark-to-market derivative liabilities	69		49
Other	1,010		484
Total deferred credits and other liabilities	8,779		8,406
Total liabilities	15,948		15,582
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,588		1,588
Other paid-in capital	5,188		5,014
Retained earnings	625		721
Accumulated other comprehensive income (loss), net	0		0
Total shareholders' equity	7,401		7,323
Total liabilities and shareholders' equity	23,349		22,905
Member's equity
Accumulated other comprehensive income (loss), net	0		0
Commonwealth Edison Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	78		75
Deferred credits and other liabilities
Regulatory liabilities	1,201		1,192
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	56		362
Restricted cash and cash equivalents	1		0
Accounts receivable, net
Customer	286		364
Other	141		161
Inventories, net
Fossil fuel	36		65
Materials and supplies	20		19
Deferred income taxes	42		40
Receivable from Exelon intercompany money pool	263		0
Prepaid utility taxes	71		21
Regulatory assets	35		32
Other	43		30
Total current assets	994		1,094
Property, plant and equipment, net	6,207		6,078
Deferred debits and other assets
Regulatory assets	1,400		1,378
Investments	23		22
Investments in affiliates	8		8
Receivable from affiliate	366		360
Prepaid pension asset	373		373
Other	36		40
Total deferred debits and other assets	2,206		2,181
Total assets	9,407		9,353
Current liabilities
Short-term notes payable - accounts receivable agreement	210		210
Long-term debt due within one year	300		300
Accounts payable	264		244
Accrued expenses	107		82
Payables to affiliates	60		76
Customer deposits	48		51
Regulatory liabilities	166		169
Other	34		26
Total current liabilities	1,189		1,158
Long-term debt	1,648		1,647
Long-term debt of variable financing trusts	184		184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,397		2,331
Asset retirement obligations	30		29
Non-pension postretirement benefit obligations	295		284
Regulatory liabilities	547		538
Other	108		113
Total deferred credits and other liabilities	3,377		3,295
Total liabilities	6,398		6,284
Commitments and contingencies	0		0
Preferred securities	0		87
Shareholders' equity
Common stock	2,388		2,388
Retained earnings	620		593
Accumulated other comprehensive income (loss), net	1	[2]	1	[2]
Total shareholders' equity	3,009		2,982
Total liabilities and shareholders' equity	9,407		9,353
Member's equity
Accumulated other comprehensive income (loss), net	1	[2]	1	[2]
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	457		89
Restricted cash and cash equivalents	0
Restricted cash and investments of variable interest entity	27		30
Accounts receivable, net
Customer	415		409
Other	145		111
Income taxes receivable	30		3
Inventories, net
Fossil fuel	44		51
Materials and supplies	34		31
Deferred income taxes	13		1
Prepaid utility taxes	1		57
Regulatory assets	142		190
Other	6		8
Total current assets	1,314		980
Property, plant and equipment, net	5,637		5,498
Deferred debits and other assets
Regulatory assets	536		522
Investments	5		5
Investments in affiliates	8		8
Prepaid pension asset	445		467
Other	23		26
Total deferred debits and other assets	1,017		1,028
Total assets	7,968		7,506
Current liabilities
Long-term debt due within one year	400		400
Long-term debt of variable interest entities due within one year	68		67
Accounts payable	138		195
Accrued expenses	105		106
Payables to affiliates	59		65
Deferred income taxes	9		0
Customer deposits	69		71
Regulatory liabilities	40		29
Other	60		47
Total current liabilities	948		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	1,761		1,658
Asset retirement obligations	7		8
Non-pension postretirement benefit obligations	223		229
Regulatory liabilities	221		214
Other	116		90
Total deferred credits and other liabilities	2,328		2,199
Total liabilities	5,510		5,148
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,360		1,360
Retained earnings	908		808
Total shareholders' equity	2,268		2,168
BGE preference stock not subject to mandatory redemption	190		190
Total equity	2,458		2,358
Total liabilities and shareholders' equity	7,968		7,506
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	21		22
Deferred credits and other liabilities
Regulatory liabilities	$ 221		$ 214

[1] (a)        Includes current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $226 million related to the fair value of the five-year financial swap contract between Generation and ComEd, as described above

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