Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Assets, Current [Abstract]
Cash and cash equivalents		$ 6,014	$ 1,878
Restricted cash and cash equivalents		274	271
Accounts receivable, net
Customer		3,227	3,482
Other		1,304	1,227
Mark-to-market derivative assets		1,405	1,279
Unamortized energy contract assets		156	254
Inventories, net
Fossil fuel and emission allowances		364	579
Materials and supplies		1,068	1,024
Deferred income taxes		173	244
Regulatory assets		785	847
Disposal Group, Including Discontinued Operation, Assets, Current		1	147
Other		654	865
Total current assets		15,425	12,097
Property, plant and equipment, net		53,935	52,087
Deferred debits and other assets
Regulatory assets		5,976	6,076
Nuclear decommissioning trust funds		10,607	10,537
Investments		607	544
Goodwill		2,672	2,672
Mark-to-market derivative assets		811	773
Unamortized energy contracts assets		526	549
Deferred Tax Assets, Net, Noncurrent		2	0
Pledged assets for Zion Station decommissioning		264	319
Other		1,388	1,160
Total deferred debits and other assets		22,853	22,630
Total assets		92,213	86,814
Liabilities, Current [Abstract]
Short-term borrowings		543	460
Long-term debt due within one year		226	1,802
Accounts payable		2,727	3,048
Accrued expenses		1,366	1,539
Regulatory liabilities		409	310
Mark-to-market derivative liabilities (current liabilities)		165	234
Unamortized energy contract liabilities		141	238
Other Liabilities, Current		941	1,123
Due to Affiliate, Current		8	8
Total current liabilities		6,526	8,762
Long-term debt		25,220	19,362
Long-term debt to financing trusts		648	648
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		13,309	13,019
Asset retirement obligations		7,550	7,295
Pension obligations		3,134	3,366
Non-pension postretirement benefit obligations		1,850	1,742
Spent nuclear fuel obligation		1,021	1,021
Regulatory liabilities		4,462	4,550
Mark-to-market derivative liabilities (noncurrent liabilities)		595	403
Unamortized energy contract liabilities		166	211
Payable for Zion Station decommissioning		135	155
Other		2,528	2,147
Total deferred credits and other liabilities		34,750	33,909
Total liabilities	[1]	$ 67,144	$ 62,681
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		$ 16,755	$ 16,709
Treasury stock, at cost (35 shares at both June 30, 2015 and December 31, 2014)		(2,327)	(2,327)
Retained earnings		11,704	10,910
Accumulated other comprehensive loss, net	[2]	(2,626)	(2,684)
Total shareholders’ equity		23,506	22,608
BGE preference stock not subject to mandatory redemption		193	193
Noncontrolling interest		1,370	1,332
Total equity		25,069	24,133
Total liabilities and shareholders’ equity		92,213	86,814
Member’s equity
Accumulated other comprehensive loss, net	[2]	(2,626)	(2,684)
Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		7,989	8,160
Deferred credits and other liabilities
Total liabilities		2,555	2,723
Exelon Generation Co L L C [Member]
Assets, Current [Abstract]
Cash and cash equivalents		456	780
Restricted cash and cash equivalents		174	158
Accounts receivable, net
Customer		2,045	2,295
Other		299	318
Mark-to-market derivative assets		1,405	1,276
Unamortized energy contract assets		156	254
Receivables from affiliates		103	113
Inventories, net
Fossil fuel and emission allowances		305	465
Materials and supplies		860	847
Deferred income taxes		188	327
Disposal Group, Including Discontinued Operation, Assets, Current		1	147
Other		451	658
Total current assets		6,443	7,638
Property, plant and equipment, net		23,766	22,945
Deferred debits and other assets
Nuclear decommissioning trust funds		10,607	10,537
Investments		183	104
Goodwill		47	47
Mark-to-market derivative assets		790	771
Unamortized energy contracts assets		526	549
Deferred Tax Assets, Net, Noncurrent		2	3
Pledged assets for Zion Station decommissioning		264	319
Other		798	731
Prepaid pension asset		1,699	1,704
Total deferred debits and other assets		14,916	14,765
Total assets	[3]	45,125	45,348
Liabilities, Current [Abstract]
Short-term borrowings		40	36
Long-term debt due within one year		89	58
Accounts payable		1,528	1,759
Accrued expenses		732	886
Mark-to-market derivative liabilities (current liabilities)		145	214
Unamortized energy contract liabilities		141	238
Other Liabilities, Current		453	605
Payables to affiliates		98	107
Related Party Transaction, Due from (to) Related Party		638	0
Due to Affiliate, Current		0	556
Total current liabilities		3,864	4,459
Long-term debt		7,974	6,709
Long-term debt to affiliate		938	943
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		6,009	6,034
Asset retirement obligations		7,399	7,146
Non-pension postretirement benefit obligations		922	915
Spent nuclear fuel obligation		1,021	1,021
Mark-to-market derivative liabilities (noncurrent liabilities)		392	105
Unamortized energy contract liabilities		166	211
Payable for Zion Station decommissioning		135	155
Other		817	719
Payables to affiliates		2,832	2,880
Total deferred credits and other liabilities		19,693	19,186
Total liabilities	[3]	$ 32,469	$ 31,297
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Accumulated other comprehensive loss, net	[2]	$ (47)	$ (36)
Noncontrolling interest		1,370	1,333
Member’s equity
Membership interest		8,951	8,951
Undistributed earnings		2,382	3,803
Accumulated other comprehensive loss, net	[2]	(47)	(36)
Total member's equity		11,286	12,718
Total equity		12,656	14,051
Total liabilities and equity		45,125	45,348
Exelon Generation Co L L C [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		7,949	8,119
Deferred credits and other liabilities
Total liabilities		2,435	2,507
Commonwealth Edison Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		51	66
Restricted cash and cash equivalents		4	4
Accounts receivable, net
Customer		522	477
Other		569	648
Receivables from affiliates		14	14
Inventories, net
Regulatory assets		276	349
Other		36	40
Inventories, net		144	125
Total current assets		1,616	1,723
Property, plant and equipment, net		16,493	15,793
Deferred debits and other assets
Regulatory assets		834	852
Goodwill		2,625	2,625
Other		283	277
Receivable from affiliate		2,538	2,571
Prepaid pension asset		1,572	1,551
Total deferred debits and other assets		7,852	7,876
Total assets		25,961	25,392
Liabilities, Current [Abstract]
Short-term borrowings		503	304
Long-term debt due within one year		0	260
Accounts payable		580	598
Accrued expenses		291	331
Deferred income taxes		20	63
Regulatory liabilities		154	125
Mark-to-market derivative liabilities (current liabilities)		20	20
Other Liabilities, Current		75	73
Customer deposits		128	128
Due to Affiliate, Current		73	84
Total current liabilities		1,844	1,986
Long-term debt		6,099	5,698
Long-term debt to financing trusts		206	206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		4,579	4,498
Asset retirement obligations		103	103
Non-pension postretirement benefit obligations		262	263
Regulatory liabilities		3,622	3,655
Mark-to-market derivative liabilities (noncurrent liabilities)		203	187
Other		1,049	889
Total deferred credits and other liabilities		9,818	9,595
Total liabilities		$ 17,967	$ 17,485
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		$ 1,588	$ 1,588
Retained earnings		890	851
Other paid-in capital		5,516	5,468
Total shareholders’ equity		7,994	7,907
Total liabilities and shareholders’ equity		25,961	25,392
PECO Energy Co [Member]
Assets, Current [Abstract]
Cash and cash equivalents		26	30
Restricted cash and cash equivalents		3	2
Accounts receivable, net
Customer		301	320
Other		122	141
Receivables from affiliates		3	3
Inventories, net
Fossil fuel and emission allowances		30	57
Materials and supplies		28	22
Deferred income taxes		69	69
Regulatory assets		42	29
Other		36	31
Prepaid utility taxes		80	10
Total current assets		740	714
Property, plant and equipment, net		6,957	6,801
Deferred debits and other assets
Regulatory assets		1,552	1,529
Investments		28	31
Other		31	34
Receivable from affiliate		477	490
Prepaid pension asset		341	344
Total deferred debits and other assets		2,429	2,428
Total assets		10,126	9,943
Liabilities, Current [Abstract]
Accounts payable		319	337
Accrued expenses		116	91
Regulatory liabilities		117	90
Other Liabilities, Current		41	31
Payables to affiliates		41	0
Customer deposits		54	52
Due to Affiliate, Current		50	52
Total current liabilities		738	653
Long-term debt		2,246	2,246
Long-term debt to financing trusts		184	184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		2,724	2,671
Asset retirement obligations		30	29
Non-pension postretirement benefit obligations		287	287
Regulatory liabilities		633	657
Other		93	95
Total deferred credits and other liabilities		3,767	3,739
Total liabilities		$ 6,935	$ 6,822
Commitments and contingencies
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		$ 2,439	$ 2,439
Retained earnings		751	681
Accumulated other comprehensive loss, net	[2]	1	1
Total shareholders’ equity		3,191	3,121
Total liabilities and shareholders’ equity		10,126	9,943
Member’s equity
Accumulated other comprehensive loss, net	[2]	1	1
Baltimore Gas and Electric Company [Member]
Assets, Current [Abstract]
Cash and cash equivalents		24	64
Restricted cash and cash equivalents		29	50
Accounts receivable, net
Customer		360	390
Other		76	82
Inventories, net
Fossil fuel and emission allowances		29	57
Materials and supplies		35	30
Deferred income taxes		12	6
Regulatory assets		207	214
Other		4	5
Prepaid utility taxes		0	59
Total current assets		776	957
Property, plant and equipment, net		6,373	6,204
Deferred debits and other assets
Regulatory assets		486	510
Investments		13	12
Other		25	25
Prepaid pension asset		344	370
Total deferred debits and other assets		868	917
Total assets	[4]	8,017	8,078
Liabilities, Current [Abstract]
Short-term borrowings		0	120
Long-term debt due within one year		77	75
Accounts payable		194	215
Accrued expenses		108	131
Deferred income taxes		48	52
Regulatory liabilities		91	44
Other Liabilities, Current		33	51
Customer deposits		97	92
Due to Affiliate, Current		52	66
Total current liabilities		700	846
Long-term debt		1,828	1,867
Long-term debt to financing trusts		258	258
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits		1,930	1,865
Asset retirement obligations		18	17
Non-pension postretirement benefit obligations		209	212
Regulatory liabilities		185	200
Other		62	60
Total deferred credits and other liabilities		2,404	2,354
Total liabilities	[4]	5,190	5,325
Stockholders' Equity Attributable to Parent [Abstract]
Common stock		1,360	1,360
Retained earnings		1,277	1,203
Total shareholders’ equity		2,637	2,563
BGE preference stock not subject to mandatory redemption		190	190
Total equity		2,827	2,753
Total liabilities and shareholders' equity		8,017	8,078
Baltimore Gas and Electric Company [Member] | Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member]
Deferred debits and other assets
Total assets		27	24
Deferred credits and other liabilities
Total liabilities		$ 160	$ 197	[4]

[1] Exelon’s consolidated assets include $7,989 million and $8,160 million at June 30, 2015 and December 31, 2014, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $2,555 million and $2,723 million at June 30, 2015 and December 31, 2014, 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 parentheses represent a decrease in accumulated other comprehensive income.

[3] Generation’s consolidated assets include $7,949 million and $8,119 million at June 30, 2015 and December 31, 2014, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Generation’s consolidated liabilities include $2,435 million and $2,507 million at June 30, 2015 and December 31, 2014, 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 $27 million and $24 million at June 30, 2015 and December 31, 2014, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $160 million and $197 million at June 30, 2015 and December 31, 2014, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 — Variable Interest Entities.