Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Assets, Current [Abstract]
Cash and cash equivalents	$ 2,763		$ 1,609
Restricted cash and cash equivalents	318		167
Accounts receivable, net
Customer	2,815		2,981
Other	898		1,175
Mark-to-market derivative assets	744		727
Unamortized energy contract assets	225		374
Inventories, net
Fossil fuel	546		276
Materials and supplies	1,045		829
Deferred income taxes	38		573
Regulatory assets	774		760
Assets held for sale	649		14
Other	1,022		652
Total current assets	11,837		10,137
Property, plant and equipment, net	51,630		47,330
Deferred debits and other assets
Regulatory assets	5,589		5,910
Nuclear decommissioning trust funds	10,349		8,071
Investments	562		1,165
Investments in affiliates	26		22
Investment in CENG	0		1,925
Goodwill	2,672		2,625
Mark-to-market derivative assets	524		607
Unamortized energy contracts assets	571		710
Pledged assets for Zion Station decommissioning	365		458
Other	1,139		964
Total deferred debits and other assets	21,797		22,457
Total assets	85,264		79,924
Liabilities, Current [Abstract]
Short-term borrowings	562		341
Long-term debt due within one year	2,064		1,509
Accounts payable	2,502		2,484
Accrued expenses	1,462		1,633
Payables to affiliates	22		116
Deferred income taxes	26		40
Regulatory liabilities	364		327
Mark-to-market derivative liabilities (current liabilities)	249		159
Unamortized energy contract liabilities	195		261
Other	985		858
Total current liabilities	8,431		7,728
Long-term debt	19,200		17,623
Long-term debt to financing trusts	648		648
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	13,181		12,905
Asset retirement obligations	7,003		5,194
Pension obligations	1,809		1,876
Non-pension postretirement benefit obligations	1,459		2,190
Spent nuclear fuel obligation	1,021		1,021
Regulatory liabilities	4,593		4,388
Mark-to-market derivative liabilities (noncurrent liabilities)	291		300
Unamortized energy contract liabilities	214		266
Payable for Zion Station decommissioning	260		305
Other	2,104		2,540
Total deferred credits and other liabilities	31,935		30,985
Total liabilities	60,214	[1]	56,984	[1]
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	16,679		16,741
Treasury stock, at cost (35 shares at both September 30, 2014 and December 31, 2013)	(2,327)		(2,327)
Retained earnings	11,160		10,358
Accumulated other comprehensive loss, net	(1,917)	[2]	(2,040)	[2]
Total shareholders’ equity	23,595		22,732
BGE preference stock not subject to mandatory redemption	193		193
Noncontrolling interest	1,262		15
Total equity	25,050		22,940
Total liabilities and shareholders’ equity	85,264		79,924
Member’s equity
Accumulated other comprehensive loss, net	(1,917)	[2]	(2,040)	[2]
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	7,773		1,755
Deferred credits and other liabilities
Total liabilities	2,594		658
Exelon Generation Co L L C [Member]
Assets, Current [Abstract]
Cash and cash equivalents	1,311		1,258
Restricted cash and cash equivalents	187		71
Accounts receivable, net
Customer	1,705		1,689
Other	325		353
Mark-to-market derivative assets	744		727
Unamortized energy contract assets	225		374
Receivables from affiliates	56		108
Receivable from Exelon intercompany money pool	0		44
Inventories, net
Fossil fuel	426		164
Materials and supplies	865		671
Deferred income taxes	144		475
Assets held for sale	649		14
Other	821		491
Total current assets	7,458		6,439
Property, plant and equipment, net	23,143		20,111
Deferred debits and other assets
Nuclear decommissioning trust funds	10,349		8,071
Investments	154		400
Investment in CENG	0		1,925
Goodwill	47		0
Mark-to-market derivative assets	507		600
Unamortized energy contracts assets	571		710
Pledged assets for Zion Station decommissioning	365		458
Other	714		645
Prepaid pension asset	1,711		1,873
Total deferred debits and other assets	14,418		14,682
Total assets	45,019		41,232
Liabilities, Current [Abstract]
Short-term borrowings	14		22
Long-term debt due within one year	73		561
Accounts payable	1,318		1,322
Accrued expenses	840		976
Payables to affiliates	560		0
Deferred income taxes	1		25
Mark-to-market derivative liabilities (current liabilities)	235		142
Unamortized energy contract liabilities	192		249
Other	478		389
Payables to affiliates	124		181
Total current liabilities	3,835		3,867
Long-term debt	6,741		5,645
Long-term debt to affiliate	946		1,523
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	6,202		6,295
Asset retirement obligations	6,853		5,047
Non-pension postretirement benefit obligations	949		850
Spent nuclear fuel obligation	1,021		1,021
Mark-to-market derivative liabilities (noncurrent liabilities)	104		120
Unamortized energy contract liabilities	214		266
Payable for Zion Station decommissioning	260		305
Other	718		811
Payables to affiliates	2,850		2,740
Total deferred credits and other liabilities	19,171		17,455
Total liabilities	30,693	[3]	28,490	[3]
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Accumulated other comprehensive loss, net	11	[2]	214	[2]
Noncontrolling interest	1,263		17
Member’s equity
Membership interest	8,953		8,898
Undistributed earnings	4,099		3,613
Accumulated other comprehensive loss, net	11	[2]	214	[2]
Total member's equity	13,063		12,725
Total equity	14,326		12,742
Total liabilities and equity	45,019		41,232
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	7,703		1,695
Deferred credits and other liabilities
Total liabilities	2,338		362
Commonwealth Edison Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents	44		36
Restricted cash and cash equivalents	4		2
Accounts receivable, net
Customer	486		451
Other	455		581
Receivables from affiliates	3		3
Inventories, net
Regulatory assets	330		329
Other	37		29
Inventories, net	121		109
Total current assets	1,480		1,540
Property, plant and equipment, net	15,389		14,666
Deferred debits and other assets
Regulatory assets	928		933
Investments	0		5
Investments in affiliates	6		6
Goodwill	2,625		2,625
Other	278		291
Receivable from affiliate	2,551		2,469
Prepaid pension asset	1,588		1,583
Total deferred debits and other assets	7,976		7,912
Total assets	24,845		24,118
Liabilities, Current [Abstract]
Short-term borrowings	528		184
Long-term debt due within one year	260		617
Accounts payable	571		449
Accrued expenses	254		307
Payables to affiliates	28		83
Deferred income taxes	117		16
Regulatory liabilities	187		170
Mark-to-market derivative liabilities (current liabilities)	14		17
Other	73		72
Customer deposits	128		133
Total current liabilities	2,160		2,048
Long-term debt	5,448		5,058
Long-term debt to financing trusts	206		206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,170		4,116
Asset retirement obligations	103		99
Non-pension postretirement benefit obligations	278		381
Regulatory liabilities	3,643		3,512
Mark-to-market derivative liabilities (noncurrent liabilities)	164		176
Other	868		994
Total deferred credits and other liabilities	9,226		9,278
Total liabilities	17,040		16,590
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	1,588		1,588
Retained earnings	855		750
Other paid-in capital	5,362		5,190
Total shareholders’ equity	7,805		7,528
Total liabilities and shareholders’ equity	24,845		24,118
PECO Energy Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents	346		217
Restricted cash and cash equivalents	2		2
Accounts receivable, net
Customer	258		360
Other	105		103
Receivables from affiliates	3		4
Inventories, net
Fossil fuel	52		60
Materials and supplies	24		21
Deferred income taxes	83		83
Regulatory assets	21		17
Other	44		36
Prepaid utility taxes	44		3
Total current assets	982		906
Property, plant and equipment, net	6,648		6,384
Deferred debits and other assets
Regulatory assets	1,520		1,448
Investments	23		23
Investments in affiliates	8		8
Other	39		38
Receivable from affiliate	479		447
Prepaid pension asset	352		363
Total deferred debits and other assets	2,421		2,327
Total assets	10,051		9,617
Liabilities, Current [Abstract]
Long-term debt due within one year	250		250
Accounts payable	303		285
Accrued expenses	121		106
Payables to affiliates	38		58
Regulatory liabilities	79		106
Other	26		37
Customer deposits	53		49
Total current liabilities	870		891
Long-term debt	2,246		1,947
Long-term debt to financing trusts	184		184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,574		2,487
Asset retirement obligations	30		29
Non-pension postretirement benefit obligations	291		286
Regulatory liabilities	655		629
Other	97		99
Total deferred credits and other liabilities	3,647		3,530
Total liabilities	6,947		6,552
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	2,439		2,415
Retained earnings	664		649
Accumulated other comprehensive loss, net	1	[2]	1	[2]
Total shareholders’ equity	3,104		3,065
Total liabilities and shareholders’ equity	10,051		9,617
Member’s equity
Accumulated other comprehensive loss, net	1	[2]	1	[2]
Baltimore Gas and Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents	27		31
Restricted cash and cash equivalents	65		28
Accounts receivable, net
Customer	366		480
Other	90		114
Income taxes receivable	0		30
Inventories, net
Fossil fuel	68		53
Materials and supplies	34		28
Deferred income taxes	5		2
Regulatory assets	206		181
Other	6		7
Prepaid utility taxes	2		57
Total current assets	869		1,011
Property, plant and equipment, net	6,126		5,864
Deferred debits and other assets
Regulatory assets	500		524
Investments	4		5
Investments in affiliates	8		8
Other	26		26
Prepaid pension asset	382		423
Total deferred debits and other assets	920		986
Total assets	7,915		7,861
Liabilities, Current [Abstract]
Short-term borrowings	20		135
Long-term debt due within one year	72		70
Accounts payable	207		270
Accrued expenses	167		111
Payables to affiliates	56		55
Deferred income taxes	52		27
Regulatory liabilities	45		48
Other	45		35
Customer deposits	93		76
Total current liabilities	757		827
Long-term debt	1,904		1,941
Long-term debt to financing trusts	258		258
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,805		1,773
Asset retirement obligations	18		19
Non-pension postretirement benefit obligations	213		217
Regulatory liabilities	199		204
Other	60		67
Total deferred credits and other liabilities	2,295		2,280
Total liabilities	5,214	[4]	5,306	[4]
Stockholders' Equity Attributable to Parent [Abstract]
Common stock	1,360		1,360
Retained earnings	1,151		1,005
Total shareholders’ equity	2,511		2,365
BGE preference stock not subject to mandatory redemption	190		190
Total equity	2,701		2,555
Total liabilities and shareholders' equity	7,915		7,861
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets	50		31
Deferred credits and other liabilities
Total liabilities	$ 237		$ 269

[1] Exelon’s consolidated assets include $7,773 million and $1,755 million at September 30, 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 $2,594 million and $658 million at September 30, 2014 and December 31, 2013, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 3 - 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 $7,703 million and $1,695 million at September 30, 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 $2,338 million and $362 million at September 30, 2014 and December 31, 2013, respectively, of certain VIEs for which the VIE creditors do not have recourse to Generation. See Note 3 - Variable Interest Entities.

[4] BGE’s consolidated assets include $50 million and $31 million at September 30, 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 $237 million and $269 million at September 30, 2014 and December 31, 2013, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.