Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 1,878		$ 1,609
Cash and cash equivalents	1,878		1,609
Restricted cash and cash equivalents	271		167
Accounts receivable, net
Customer	3,482		2,981
Other	1,227		1,175
Mark-to-market derivative assets	1,279		727
Unamortized energy contract assets	254		374
Inventories, net
Fossil fuel	579		276
Materials and supplies	1,024		829
Deferred income taxes	244		573
Regulatory assets	847		760
Assets held for sale	147		14
Other	865		652
Total current assets	12,097		10,137
Property, plant and equipment, net	52,087		47,330
Deferred debits and other assets
Regulatory assets	6,076		5,910
Nuclear decommissioning trust funds	10,537		8,071
Investments	544		1,187
Investment in CENG	0		1,925
Goodwill	2,672		2,625
Mark-to-market derivative assets	773		607
Unamortized energy contract assets	549		710
Pledged assets for Zion Station decommissioning	319		458
Other	1,160		964
Total deferred debits and other assets	22,630		22,457
Total assets	86,814	[1]	79,924	[1]
Current liabilities
Short-term borrowings	460		341
Long-term debt due within one year	1,802		1,509
Accounts payable	3,048		2,484
Accrued expenses	1,539		1,633
Payables to affiliates	8		116
Mark-to-market derivative liabilities	234		159
Unamortized energy contract liabilities	238		261
Deferred income taxes	0		40
Regulatory liabilities	310		327
Other	1,123		858
Total current liabilities	8,762		7,728
Long-term debt	19,362		17,623
Long-term debt to financing trusts	648		648
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	13,019		12,905
Asset retirement obligations	7,295		5,194
Pension obligations	3,366		1,876
Non-pension postretirement benefit obligations	1,742		2,190
Spent nuclear fuel obligation	1,021		1,021
Regulatory liabilities	4,550		4,388
Mark-to-market derivative liabilities	403		300
Unamortized energy contract liabilities	211		266
Payable for Zion Station decommissioning	155		305
Other	2,147		2,540
Total deferred credits and other liabilities	33,909		30,985
Total liabilities	62,681	[1]	56,984	[1]
Shareholders’ equity
Common stock	16,709		16,741
Treasury stock, at cost (35 shares held at December 31, 2014 and 2013)	(2,327)		(2,327)
Retained earnings	10,910		10,358
Accumulated other comprehensive loss, net	(2,684)		(2,040)	[2]
Total shareholders’ equity	22,608		22,732
BGE preference stock not subject to mandatory redemption	193		193
Noncontrolling interest	1,332		15
Total equity	24,133		22,940
Total liabilities and shareholders’ equity	86,814		79,924
Member’s equity
Accumulated other comprehensive loss, net	(2,684)		(2,040)	[2]
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	8,160		1,755
Deferred credits and other liabilities
Total liabilities	2,723		658
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	780		1,258
Cash and cash equivalents	780		1,258
Restricted cash and cash equivalents	158		71
Accounts receivable, net
Customer	2,295		1,689
Other	318		353
Mark-to-market derivative assets	1,276		727
Receivables from affiliates	113		108
Unamortized energy contract assets	254		374
Inventories, net
Fossil fuel	465		164
Materials and supplies	847		671
Deferred income taxes	327		475
Receivable from Exelon intercompany money pool	0		44
Regulatory assets	147		14
Other	658		491
Total current assets	7,638		6,439
Property, plant and equipment, net	22,945		20,111
Deferred debits and other assets
Nuclear decommissioning trust funds	10,537		8,071
Investments	104		400
Investment in CENG	0		1,925
Goodwill	47		0
Mark-to-market derivative assets	771		600
Prepaid pension asset	1,704		1,873
Unamortized energy contract assets	549		710
Deferred income taxes	3
Pledged assets for Zion Station decommissioning	319		458
Other	731		645
Total deferred debits and other assets	14,765		14,682
Total assets	45,348	[3]	41,232	[3]
Current liabilities
Short-term borrowings	36		22
Long-term debt due within one year	58		561
Long-term debt to affiliates due within one year	556		0
Accounts payable	1,759		1,322
Accrued expenses	886		976
Payables to affiliates	107		181
Mark-to-market derivative liabilities	214		142
Unamortized energy contract liabilities	238		249
Deferred income taxes	0		25
Other	605		389
Total current liabilities	4,459		3,867
Long-term debt	6,709		5,645
Long-term debt to financing trusts	943		1,523
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	6,034		6,295
Asset retirement obligations	7,146		5,047
Non-pension postretirement benefit obligations	915		850
Spent nuclear fuel obligation	1,021		1,021
Payables to affiliates	2,880		2,740
Mark-to-market derivative liabilities	105		120
Unamortized energy contract liabilities	211		266
Payable for Zion Station decommissioning	155		305
Other	719		811
Total deferred credits and other liabilities	19,186		17,455
Total liabilities	31,297	[3]	28,490	[3]
Shareholders’ equity
Accumulated other comprehensive loss, net	(36)		214	[2]
Noncontrolling interest	1,333		17
Member’s equity
Membership interest	8,951		8,898
Undistributed earnings	3,803		3,613
Accumulated other comprehensive loss, net	(36)		214	[2]
Total member’s equity	12,718		12,725
Total equity	14,051		12,742
Total liabilities and equity	45,348		41,232
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	8,119		1,695
Deferred credits and other liabilities
Total liabilities	2,507		362
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	66		36
Restricted cash and cash equivalents	4		2
Accounts receivable, net
Customer	477		451
Other	648		581
Receivables from affiliates	14		3
Inventories, net
Inventories, net	125		109
Regulatory assets	349		329
Other	40		29
Total current assets	1,723		1,540
Property, plant and equipment, net	15,793		14,666
Deferred debits and other assets
Regulatory assets	852		933
Investments	6		11
Goodwill	2,625		2,625
Receivable from affiliates	2,571		2,469
Prepaid pension asset	1,551		1,583
Other	271		291
Total deferred debits and other assets	7,876		7,912
Total assets	25,392		24,118
Current liabilities
Short-term borrowings	304		184
Long-term debt due within one year	260		617
Accounts payable	598		449
Accrued expenses	331		307
Payables to affiliates	84		83
Mark-to-market derivative liabilities	20		17
Deferred income taxes	63		16
Customer deposits	128		133
Regulatory liabilities	125		170
Other	73		72
Total current liabilities	1,986		2,048
Long-term debt	5,698		5,058
Long-term debt to financing trusts	206		206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,498		4,116
Asset retirement obligations	103		99
Non-pension postretirement benefit obligations	263		381
Regulatory liabilities	3,655		3,512
Mark-to-market derivative liabilities	187		176
Other	889		994
Total deferred credits and other liabilities	9,595		9,278
Total liabilities	17,485		16,590
Shareholders’ equity
Common stock	1,588		1,588
Other paid-in capital	5,468		5,190
Retained earnings	851		750
Total shareholders’ equity	7,907		7,528
Total liabilities and shareholders’ equity	25,392		24,118
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	30		217
Restricted cash and cash equivalents	2		2
Accounts receivable, net
Customer	320		360
Other	141		104
Receivables from affiliates	3		3
Inventories, net
Fossil fuel	57		60
Materials and supplies	22		21
Deferred income taxes	69		83
Prepaid utility taxes	10		3
Regulatory assets	29		17
Other	31		36
Total current assets	714		906
Property, plant and equipment, net	6,801		6,384
Deferred debits and other assets
Regulatory assets	1,529		1,448
Investments	31		31
Receivable from affiliates	490		447
Prepaid pension asset	344		363
Other	34		38
Total deferred debits and other assets	2,428		2,327
Total assets	9,943		9,617
Current liabilities
Long-term debt due within one year	0		250
Accounts payable	337		285
Accrued expenses	91		106
Payables to affiliates	52		58
Customer deposits	52		49
Regulatory liabilities	90		106
Other	31		37
Total current liabilities	653		891
Long-term debt	2,246		1,947
Long-term debt to financing trusts	184	[4]	184	[4]
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,671		2,487
Asset retirement obligations	29		29
Non-pension postretirement benefit obligations	287		286
Regulatory liabilities	657		629
Mark-to-market derivative liabilities	14
Other	95		99
Total deferred credits and other liabilities	3,739		3,530
Total liabilities	6,822		6,552
Shareholders’ equity
Common stock	2,439		2,415
Retained earnings	681		649
Accumulated other comprehensive loss, net	1		1	[2]
Total shareholders’ equity	3,121		3,065
Total liabilities and shareholders’ equity	9,943		9,617
Member’s equity
Accumulated other comprehensive loss, net	1		1	[2]
Baltimore Gas and Electric Company [Member]
Current assets
Cash and cash equivalents	64		31
Restricted cash and cash equivalents	50		28
Accounts receivable, net
Customer	390		480
Other	82		114
Income taxes receivable	0		30
Inventories, net
Fossil fuel	57		53
Materials and supplies	30		28
Deferred income taxes	6		2
Prepaid utility taxes	59		57
Regulatory assets	214		181
Other	5		7
Total current assets	957		1,011
Property, plant and equipment, net	6,204		5,864
Deferred debits and other assets
Regulatory assets	510		524
Investments	12		13
Prepaid pension asset	370		423
Other	25		26
Total deferred debits and other assets	917		986
Total assets	8,078	[5]	7,861	[5]
Current liabilities
Short-term borrowings	120		135
Long-term debt to affiliates due within one year	75		70
Accounts payable	215		270
Accrued expenses	131		111
Payables to affiliates	66		55
Deferred income taxes	52		27
Customer deposits	92		76
Regulatory liabilities	44		48
Other	51		35
Total current liabilities	846		827
Long-term debt	1,867		1,941
Long-term debt to financing trusts	258		258
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,865		1,773
Asset retirement obligations	17		19
Non-pension postretirement benefit obligations	212		217
Regulatory liabilities	200		204
Other	60		67
Total deferred credits and other liabilities	2,354		2,280
Total liabilities	5,325	[5]	5,306	[5]
Shareholders’ equity
Common stock	1,360		1,360
Retained earnings	1,203		1,005
Total shareholders’ equity	2,563		2,365
BGE preference stock not subject to mandatory redemption	190		190
Total equity	2,753		2,555
Total liabilities and shareholders’ equity	8,078		7,861
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	24		31
Deferred credits and other liabilities
Total liabilities	197		269
Constellation Energy Group LLC [Member]
Deferred debits and other assets
Total assets	$ 189

[1] Exelon’s consolidated assets include $8,160 million and $1,755 million at December 31, 2014 and December 31, 2013, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $2,723 million and $658 million at December 31, 2014 and December 31, 2013, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 2–Variable Interest Entities.

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

[3] Generation’s consolidated assets include $8,119 million and $1,695 million at December 31, 2014 and December 31, 2013, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $2,507 million and $362 million at December 31, 2014 and December 31, 2013, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 2–Variable Interest Entities.

[4] Amounts owed to this financing trust are recorded as Long-term debt to financing trusts within PECO’s Consolidated Balance Sheets.

[5] BGE’s consolidated assets include $24 million and $31 million at December 31, 2014 and December 31, 2013, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $197 million and $269 million at December 31, 2014 and December 31, 2013, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 2 - Variable Interest Entities.