Consolidated Balance Sheets (Unaudited) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013
Current assets
CashAndCashEquivalentsNonvariableInterestEntity	$ 791		$ 1,547
Cash and cash equivalents	914		1,609		772
Cash and cash equivalents of variable interest entities	123		62
Restricted cash and investments	111		87
Restricted cash and investments of variable interest entity	96		80
Accounts receivable, net
Customer	2,997		2,721
Other	871		1,175
Accounts receivable of variable interest entities	458		260
Mark-to-market derivative assets	756		727
Unamortized energy contracts assets	326		374
Inventories, net
Fossil fuel	180		276
Materials and supplies	843		829
Deferred income taxes	454		573
Regulatory assets	768		760
Other	901		666
Total current assets	9,675		10,137
Property, plant and equipment, net	47,742		47,330
Deferred debits and other assets
Regulatory assets	5,863		5,910
Nuclear decommissioning trust funds	8,215		8,071
Investments	825		1,165
Investments in affiliates	22		22
Investment in CENG	1,910		1,925
Goodwill	2,625		2,625
Mark-to-market derivative assets	571		607
Pledged assets for Zion Station decommissioning	429		458
Unamortized energy contracts assets	657		710
Other	934		964
Deferred income taxes	0				0
Total deferred debits and other assets	22,051		22,457
Total assets	79,468		79,924		79,924
Current liabilities
Short-term borrowings	980		341
Long-term debt due within one year	292		1,424
Long-term debt of variable interest entities due within one year	81		85
Accounts payable	2,475		2,314
Accounts payable of variable interest entities	286		170
Accrued expenses	1,364		1,633
Payables to affiliates	94		116
Deferred income taxes	22		40
Regulatory liabilities	336		327
Mark-to-market derivative liabilities	251		159
Unamortized energy contract liabilities	238		261
Other	932		858
Total current liabilities	7,351		7,728
Long-term debt	18,247		17,325
Long-term debt of variable financing trusts	648		648
Long-term debt of variable interest entity	300		298
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	12,810		12,905
Asset retirement obligations	5,261		5,194
Pension obligations	1,661		1,876
Non-pension postretirement benefit obligations	2,042		2,190
Spent nuclear fuel obligation	1,021		1,021
Regulatory liabilities	4,458		4,388
Mark-to-market derivative liabilities	287		300
Unamortized energy contract liabilities	230		266
Payable for Zion Station decommissioning	281		305
Other	2,093		2,540
Total deferred credits and other liabilities	30,144		30,985
Total liabilities	56,690		56,984
Shareholders' equity
Common stock	16,751		16,741
Treasury stock, at cost (35 and 35 shares held at December 31, 2010 and December 31, 2009, respectively)	(2,327)		(2,327)
Retained earnings	10,180		10,358
Accumulated other comprehensive income (loss), net	(2,036)	[1]	(2,040)	[1]	(2,673)	[1]
Total shareholders' equity	22,568		22,732
BGE preference stock not subject to mandatory redemption	193		193
Noncontrolling interest	17		15
Total equity	22,778		22,940
Total liabilities and shareholders' equity	79,468		79,924
Member's equity
Accumulated other comprehensive income (loss), net	(2,036)	[1]	(2,040)	[1]	(2,673)	[1]
Removal Costs [Member]
Current liabilities
Regulatory liabilities	105		99
Deferred credits and other liabilities
Regulatory liabilities	1,440		1,423
Exelon Generation Co L L C [Member]
Current assets
CashAndCashEquivalentsNonvariableInterestEntity	443		1,196
Cash and cash equivalents	566		1,258		225
Cash and cash equivalents of variable interest entities	123		62
Restricted cash and cash equivalents	19		19
Restricted cash and investments of variable interest entity	43		52
Accounts receivable, net
Customer	1,521		1,429
Other	388		353
Accounts receivable of variable interest entities	458		260
Mark-to-market derivative assets	756		727
Mark-to-market derivative assets with affiliates	0		0
Receivables from affiliates	122		108
Unamortized energy contracts assets	326		374
Inventories, net
Fossil fuel	153		164
Materials and supplies	679		671
Deferred income taxes	529		475
Receivable from Exelon intercompany money pool	0		44
Other	629		505
Total current assets	6,189		6,439
Property, plant and equipment, net	20,132		20,111
Deferred debits and other assets
Nuclear decommissioning trust funds	8,215		8,071
Investments	401		400
Investments in affiliates	0		0
Investment in CENG	1,910		1,925
Goodwill	0		0
Mark-to-market derivative assets	561		600
Mark-to-market derivative assets with affiliates	0		0
Prepaid pension asset	1,935		1,873
Pledged assets for Zion Station decommissioning	429		458
Unamortized energy contracts assets	657		710
Other	651		645
Deferred income taxes	0		0
Total deferred debits and other assets	14,759		14,682
Total assets	41,080		41,232
Current liabilities
Short-term borrowings	377		22
Long-term debt due within one year	42		556
Long-term debt of variable interest entities due within one year	5		5
Accounts payable	1,191		1,152
Accounts payable of variable interest entities	286		170
Accrued expenses	831		976
Payables to affiliates	186		181
Borrowings from Exelon intercompany money pool	0
Deferred income taxes	0		25
Mark-to-market derivative liabilities	238		142
Unamortized energy contract liabilities	228		249
Other	431		389
Total current liabilities	3,815		3,867
Long-term debt	5,840		5,559
Long-term debt to affiliate	1,517		1,523
Long-term debt of variable interest entity	86		86
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	6,223		6,295
Asset retirement obligations	5,114		5,047
Non-pension postretirement benefit obligations	796		850
Spent nuclear fuel obligation	1,021		1,021
Payables to affiliates	2,773		2,740
Mark-to-market derivative liabilities	131		120
Unamortized energy contract liabilities	230				266
Payable for Zion Station decommissioning	281				305
Other	745		811
Total deferred credits and other liabilities	17,314		17,455
Total liabilities	28,572		28,490
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	193	[1]	214	[1]	409	[1]
Noncontrolling interest	19		17
Member's equity
Membership interest	8,898		8,898
Undistributed earnings	3,398		3,613
Accumulated other comprehensive income (loss), net	193	[1]	214	[1]	409	[1]
Total member's equity	12,489		12,725
Total equity	12,508		12,742
Total liabilities and equity	41,080		41,232
Commonwealth Edison Co [Member]
Current assets
CashAndCashEquivalentsNonvariableInterestEntity	41		36
Cash and cash equivalents	41		36		30
Restricted cash and cash equivalents	2		2
Accounts receivable, net
Customer	475		451
Other	395		584
Inventories, net
Inventories, net	107		109
Deferred income taxes	0		0
Receivable from Exelon intercompany money pool	172
Counterparty collateral deposited	0		0
Regulatory assets	340		329
Other	57		29
Total current assets	1,417		1,540
Property, plant and equipment, net	14,890		14,666
Deferred debits and other assets
Regulatory assets	918		933
Investments	2		5
Investments in affiliates	6		6
Goodwill	2,625		2,625
Receivable from affiliate	2,497		2,469
Prepaid pension asset	1,663		1,583
Other	276		291
Total deferred debits and other assets	7,987		7,912
Total assets	24,294		24,118
Current liabilities
Short-term borrowings	534		184
Long-term debt due within one year	0		617
Accounts payable	502		449
Accrued expenses	214		307
Payables to affiliates	63		83
Deferred income taxes	116		16
Customer deposits	133		133
Regulatory liabilities	158		170
Mark-to-market derivative liabilities	13		17
Mark-to-market derivative liabilities with affiliate	0		0
Other	83		72
Total current liabilities	1,816		2,048
Long-term debt	5,707		5,058
Long-term debt of variable financing trusts	206		206
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,053		4,116
Asset retirement obligations	99		99
Non-pension postretirement benefit obligations	284		381
Regulatory liabilities	3,566		3,512
Mark-to-market derivative liabilities	155		176
Other	818		994
Total deferred credits and other liabilities	8,975		9,278
Total liabilities	16,704		16,590
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,588		1,588
Other paid-in capital	5,230		5,190
Retained earnings	772		750
Accumulated other comprehensive income (loss), net	0		0
Total shareholders' equity	7,590		7,528
Total liabilities and shareholders' equity	24,294		24,118
Member's equity
Accumulated other comprehensive income (loss), net	0		0
Commonwealth Edison Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	81		78
Deferred credits and other liabilities
Regulatory liabilities	1,237		1,219
PECO Energy Co [Member]
Current assets
CashAndCashEquivalentsNonvariableInterestEntity	98		217
Cash and cash equivalents	98		217		302
Restricted cash and cash equivalents	2		2
Restricted cash and investments of variable interest entity	0		0
Accounts receivable, net
Customer	422		360
Other	120		107
Inventories, net
Fossil fuel	12		60
Materials and supplies	24		21
Deferred income taxes	83		83
Receivable from Exelon intercompany money pool	0		0
Prepaid utility taxes	104		3
Regulatory assets	28		17
Other	41		36
Total current assets	934		906
Property, plant and equipment, net	6,480		6,384
Deferred debits and other assets
Regulatory assets	1,465		1,448
Investments	23		23
Investments in affiliates	8		8
Receivable from affiliate	455		447
Prepaid pension asset	366		363
Other	35		38
Total deferred debits and other assets	2,352		2,327
Total assets	9,766		9,617
Current liabilities
Short-term notes payable - accounts receivable agreement			0
Long-term debt due within one year	250		250
Accounts payable	389		285
Accrued expenses	137		106
Payables to affiliates	60		58
Customer deposits	49		49
Regulatory liabilities	84		106
Other	29		37
Total current liabilities	998		891
Long-term debt	1,947		1,947
Long-term debt of variable financing trusts	184		184
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,508		2,487
Asset retirement obligations	29		29
Non-pension postretirement benefit obligations	290		286
Regulatory liabilities	641		629
Other	95		99
Total deferred credits and other liabilities	3,563		3,530
Total liabilities	6,692		6,552
Preferred securities			0
Shareholders' equity
Common stock	2,415		2,415
Retained earnings	658		649
Accumulated other comprehensive income (loss), net	1	[1]	1	[1]	1	[1]
Total shareholders' equity	3,074		3,065
Total liabilities and shareholders' equity	9,766		9,617
Member's equity
Accumulated other comprehensive income (loss), net	1	[1]	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
CashAndCashEquivalentsNonvariableInterestEntity	23		31
Cash and cash equivalents	23		31		115
Restricted cash and cash equivalents	0
Restricted cash and investments of variable interest entity	75		28
Accounts receivable, net
Customer	580		480
Other	136		114
Income taxes receivable	0		30
Inventories, net
Fossil fuel	16		53
Materials and supplies	32		28
Deferred income taxes	1		2
Prepaid utility taxes	28		57
Regulatory assets	168		181
Other	8		7
Total current assets	1,067		1,011
Property, plant and equipment, net	5,939		5,864
Deferred debits and other assets
Regulatory assets	504		524
Investments	4		5
Investments in affiliates	8		8
Prepaid pension asset	410		423
Other	26		26
Total deferred debits and other assets	952		986
Total assets	7,958		7,861
Current liabilities
Short-term borrowings	69		135
Long-term debt due within one year	0		0
Long-term debt of variable interest entities due within one year	70		70
Accounts payable	254		270
Accrued expenses	111		111
Payables to affiliates	59		55
Deferred income taxes	27		27
Customer deposits	82		76
Regulatory liabilities	92		48
Other	54		35
Total current liabilities	818		827
Long-term debt	1,746		1,746
Long-term debt of variable financing trusts	258		258
Long-term debt of variable interest entity	195		195
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,801		1,773
Asset retirement obligations	17		19
Non-pension postretirement benefit obligations	215		217
Regulatory liabilities	203		204
Other	65		67
Total deferred credits and other liabilities	2,301		2,280
Total liabilities	5,318		5,306
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,360		1,360
Retained earnings	1,090		1,005
Total shareholders' equity	2,450		2,365
BGE preference stock not subject to mandatory redemption	190		190
Total equity	2,640		2,555
Total liabilities and shareholders' equity	7,958		7,861
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	24		21
Deferred credits and other liabilities
Regulatory liabilities	$ 203		$ 204

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