Consolidated Balance Sheets (Unaudited) (USD $)	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011	Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 1,602,000,000		$ 1,016,000,000
Cash and cash equivalents of variable interest entities	98,000,000
Restricted cash and investments	73,000,000		40,000,000
Restricted cash and investments of variable interest entity	67,000,000
Accounts receivable, net
Customer	2,835,000,000		1,613,000,000
Other	1,216,000,000		1,000,000,000
Accounts receivable of variable interest entities	225,000,000
Mark-to-market derivative assets	928,000,000		432,000,000
Mark-to-market derivative assets with affiliates	0		0
Unamortized energy contracts assets	1,141,000,000		13,000,000
Inventories, net
Fossil fuel	264,000,000		208,000,000
Materials and supplies	767,000,000		656,000,000
Deferred income taxes	254,000,000		0
Regulatory assets	786,000,000		390,000,000
Other	1,072,000,000		345,000,000
Total current assets	11,328,000,000		5,713,000,000
Property, plant and equipment, net	43,914,000,000		32,570,000,000
Deferred debits and other assets
Regulatory assets	6,192,000,000		4,518,000,000
Nuclear decommissioning trust funds	7,140,000,000		6,507,000,000
Investments	838,000,000		751,000,000
Investments in affiliates	371,000,000		15,000,000
Investment in CENG	1,908,000,000		0
Goodwill	2,625,000,000		2,625,000,000
Mark-to-market derivative assets	1,039,000,000		650,000,000
Mark-to-market derivative assets with affiliates			0
Pledged assets for Zion Station decommissioning	631,000,000		734,000,000
Unamortized energy contracts assets	1,191,000,000		388,000,000
Other	1,176,000,000		524,000,000
Total deferred debits and other assets	23,111,000,000		16,712,000,000
Total assets	78,353,000,000		54,995,000,000
Current liabilities
Short-term borrowings	60,000,000		163,000,000
Short-term notes payable - accounts receivable agreement	225,000,000		225,000,000
Long-term debt due within one year	1,049,000,000		828,000,000
Long-term debt of variable interest entities due within one year	70,000,000		0
Accounts payable	2,359,000,000		1,444,000,000
Accounts payable of variable interest entities	132,000,000		0
Accrued expenses	1,502,000,000		1,255,000,000
Deferred income taxes	52,000,000		1,000,000
Regulatory liabilities	299,000,000		197,000,000
Dividends payable	4,000,000		349,000,000
Mark-to-market derivative liabilities	521,000,000		112,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	523,000,000		0
Other	974,000,000		560,000,000
Total current liabilities	7,770,000,000		5,134,000,000
Long-term debt	17,050,000,000		11,799,000,000
Long-term debt of variable interest entities	649,000,000		390,000,000
Long-term debt of variable interest entity	546,000,000		0
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	11,600,000,000		8,253,000,000
Asset retirement obligations	4,866,000,000		3,884,000,000
Pension obligations	2,575,000,000		2,194,000,000
Non-pension postretirement benefit obligations	2,946,000,000		2,263,000,000
Spent nuclear fuel obligation	1,020,000,000		1,019,000,000
Regulatory liabilities	4,000,000,000		3,627,000,000
Mark-to-market derivative liabilities	407,000,000		126,000,000
Mark-to-market derivative liabilities with affiliate			0
Unamortized energy contract liabilities	621,000,000		0
Payable for Zion Station decommissioning	422,000,000		563,000,000
Other	1,691,000,000		1,268,000,000
Total deferred credits and other liabilities	30,148,000,000		23,197,000,000
Total liabilities	56,163,000,000		40,520,000,000
Commitments and contingencies
Preferred securities	87,000,000		87,000,000
Shareholders' equity
Common stock	16,594,000,000		9,107,000,000
Treasury stock, at cost (35 and 35 shares held at December 31, 2010 and December 31, 2009, respectively)	(2,327,000,000)		(2,327,000,000)
Retained earnings	9,959,000,000		10,055,000,000
Accumulated other comprehensive income (loss), net	(2,405,000,000)		(2,450,000,000)
Total shareholders' equity	21,821,000,000		14,385,000,000
BGE preference stock not subject to mandatory redemption	193,000,000		0
Noncontrolling interest	89,000,000		3,000,000
Total equity	22,103,000,000		14,388,000,000
Total liabilities and shareholders' equity	78,353,000,000		54,995,000,000
Member's equity
Accumulated other comprehensive income (loss), net	(2,405,000,000)		(2,450,000,000)
Noncontrolling interest	89,000,000		3,000,000
Removal Costs [Member]
Current liabilities
Regulatory liabilities	94,000,000		61,000,000
Deferred credits and other liabilities
Regulatory liabilities	1,397,000,000		1,185,000,000
Customer Rate Credit [Member]
Current liabilities
Regulatory liabilities	1,000,000
Deferred credits and other liabilities
Regulatory liabilities	0
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	732,000,000		496,000,000
Cash and cash equivalents of variable interest entities	98,000,000
Restricted cash and cash equivalents	1,000,000		5,000,000
Restricted cash and investments of variable interest entity	19,000,000
Accounts receivable, net
Customer	1,580,000,000		578,000,000
Other	291,000,000		257,000,000
Accounts receivable of variable interest entities	225,000,000
Mark-to-market derivative assets	928,000,000		432,000,000
Mark-to-market derivative assets with affiliates	352,000,000	[1]	503,000,000	[2]
Receivables from affiliates	130,000,000		109,000,000
Unamortized energy contracts assets	1,141,000,000		13,000,000
Inventories, net
Fossil fuel	136,000,000		120,000,000
Materials and supplies	620,000,000		556,000,000
Other	905,000,000		148,000,000
Total current assets	7,158,000,000		3,217,000,000
Property, plant and equipment, net	18,708,000,000		13,475,000,000
Deferred debits and other assets
Nuclear decommissioning trust funds	7,140,000,000		6,507,000,000
Investments	82,000,000		41,000,000
Investments in affiliates	348,000,000		1,000,000
Investment in CENG	1,908,000,000		0
Mark-to-market derivative assets	1,026,000,000		635,000,000
Mark-to-market derivative assets with affiliates	0		191,000,000	[2]
Prepaid pension asset	2,021,000,000		2,068,000,000
Pledged assets for Zion Station decommissioning	631,000,000		734,000,000
Unamortized energy contracts assets	1,191,000,000		388,000,000
Other	877,000,000		176,000,000
Total deferred debits and other assets	15,224,000,000		10,741,000,000
Total assets	41,090,000,000		27,433,000,000
Current liabilities
Short-term borrowings	11,000,000		2,000,000
Long-term debt due within one year	23,000,000		3,000,000
Long-term debt of variable interest entities due within one year	4,000,000
Accounts payable	1,501,000,000		753,000,000
Accounts payable of variable interest entities	132,000,000		0
Accrued expenses	1,106,000,000		779,000,000
Payables to affiliates	99,000,000		58,000,000
Deferred income taxes	69,000,000		244,000,000
Mark-to-market derivative liabilities	504,000,000		103,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	429,000,000		0
Other	377,000,000		202,000,000
Total current liabilities	4,255,000,000		2,144,000,000
Long-term debt	7,148,000,000		3,674,000,000
Long-term debt of variable interest entity	208,000,000		0
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	5,410,000,000		3,966,000,000
Asset retirement obligations	4,730,000,000		3,767,000,000
Non-pension postretirement benefit obligations	849,000,000		703,000,000
Spent nuclear fuel obligation	1,020,000,000		1,019,000,000
Payables to affiliates	2,383,000,000		2,222,000,000
Mark-to-market derivative liabilities	355,000,000		29,000,000
Mark-to-market derivative liabilities with affiliate			0
Unamortized energy contract liabilities	589,000,000		0
Payable for Zion Station decommissioning	422,000,000		563,000,000
Other	791,000,000		638,000,000
Total deferred credits and other liabilities	16,549,000,000		12,907,000,000
Total liabilities	28,160,000,000		18,725,000,000
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	752,000,000		915,000,000
Noncontrolling interest	91,000,000		5,000,000
Member's equity
Membership interest	8,814,000,000		3,556,000,000
Undistributed earnings	3,273,000,000		4,232,000,000
Accumulated other comprehensive income (loss), net	752,000,000		915,000,000
Total member's equity	12,839,000,000		8,703,000,000
Noncontrolling interest	91,000,000		5,000,000
Total equity	12,930,000,000		8,708,000,000
Total liabilities and equity	41,090,000,000		27,433,000,000
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	31,000,000		234,000,000
Restricted cash and cash equivalents	0		3,000,000
Accounts receivable, net
Customer	602,000,000		655,000,000
Other	274,000,000		385,000,000
Inventories, net
Inventories, net	92,000,000		81,000,000
Deferred income taxes	87,000,000		61,000,000
Counterparty collateral deposited	0		90,000,000
Regulatory assets	511,000,000		657,000,000
Other	27,000,000		22,000,000
Total current assets	1,624,000,000		2,188,000,000
Property, plant and equipment, net	13,611,000,000		13,121,000,000
Deferred debits and other assets
Regulatory assets	589,000,000		699,000,000
Investments	9,000,000		21,000,000
Investments in affiliates	6,000,000		6,000,000
Goodwill	2,625,000,000		2,625,000,000
Receivable from affiliate	2,024,000,000		1,860,000,000
Mark-to-market derivative assets	0		0
Prepaid pension asset	1,698,000,000		1,803,000,000
Other	285,000,000		315,000,000
Total deferred debits and other assets	7,236,000,000		7,329,000,000
Total assets	22,471,000,000		22,638,000,000
Current liabilities
Short-term borrowings	35,000,000		0
Long-term debt due within one year	252,000,000		450,000,000
Accounts payable	326,000,000		325,000,000
Accrued expenses	220,000,000		318,000,000
Payables to affiliates	84,000,000		111,000,000
Customer deposits	137,000,000		136,000,000
Regulatory liabilities	172,000,000		137,000,000
Mark-to-market derivative liabilities	17,000,000		9,000,000
Mark-to-market derivative liabilities with affiliate	352,000,000		503,000,000
Other	128,000,000		82,000,000
Total current liabilities	1,723,000,000		2,071,000,000
Long-term debt	4,965,000,000		5,215,000,000
Long-term debt of variable interest entities	206,000,000		206,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,201,000,000		3,993,000,000
Asset retirement obligations	99,000,000		89,000,000
Non-pension postretirement benefit obligations	359,000,000		271,000,000
Regulatory liabilities	3,206,000,000		3,042,000,000
Mark-to-market derivative liabilities	53,000,000		97,000,000
Mark-to-market derivative liabilities with affiliate	0		191,000,000
Other	484,000,000		426,000,000
Total deferred credits and other liabilities	8,402,000,000		8,109,000,000
Total liabilities	15,296,000,000		15,601,000,000
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,588,000,000		1,588,000,000
Other paid-in capital	5,016,000,000		5,003,000,000
Retained earnings	571,000,000		447,000,000
Accumulated other comprehensive income (loss), net	0		(1,000,000)
Total shareholders' equity	7,175,000,000		7,037,000,000
Total liabilities and shareholders' equity	22,471,000,000		22,638,000,000
Member's equity
Accumulated other comprehensive income (loss), net	0		(1,000,000)
Commonwealth Edison Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	73,000,000		61,000,000
Deferred credits and other liabilities
Regulatory liabilities	1,185,000,000		1,185,000,000
Commonwealth Edison Co [Member] | Customer Rate Credit [Member]
Current liabilities
Regulatory liabilities	0
Deferred credits and other liabilities
Regulatory liabilities	0
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	648,000,000		194,000,000		518,000,000	522,000,000
Restricted cash and cash equivalents	0		2,000,000
Accounts receivable, net
Customer	294,000,000		380,000,000
Other	240,000,000		376,000,000
Inventories, net
Fossil fuel	75,000,000		87,000,000
Materials and supplies	20,000,000		18,000,000
Deferred income taxes	39,000,000		25,000,000
Receivable from Exelon intercompany money pool	77,000,000		82,000,000
Prepaid utility taxes	57,000,000		1,000,000
Regulatory assets	42,000,000		39,000,000
Other	38,000,000		39,000,000
Total current assets	1,530,000,000		1,243,000,000
Property, plant and equipment, net	5,996,000,000		5,874,000,000
Deferred debits and other assets
Regulatory assets	1,323,000,000		1,216,000,000
Investments	23,000,000		22,000,000
Investments in affiliates	8,000,000		8,000,000
Receivable from affiliate	362,000,000		365,000,000
Prepaid pension asset	378,000,000		382,000,000
Other	41,000,000		46,000,000
Total deferred debits and other assets	2,135,000,000		2,039,000,000
Total assets	9,661,000,000		9,156,000,000
Current liabilities
Short-term notes payable - accounts receivable agreement	225,000,000		225,000,000
Long-term debt due within one year	375,000,000		375,000,000
Accounts payable	200,000,000		262,000,000
Accrued expenses	87,000,000		83,000,000
Payables to affiliates	76,000,000		62,000,000
Customer deposits	51,000,000		53,000,000
Regulatory liabilities	105,000,000		60,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Other	26,000,000		25,000,000
Total current liabilities	1,145,000,000		1,145,000,000
Long-term debt	1,947,000,000		1,597,000,000
Long-term debt of variable interest entities	184,000,000		184,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,281,000,000		2,170,000,000
Asset retirement obligations	29,000,000		28,000,000
Non-pension postretirement benefit obligations	310,000,000		288,000,000
Regulatory liabilities	582,000,000		585,000,000
Other	118,000,000		134,000,000
Total deferred credits and other liabilities	3,320,000,000		3,205,000,000
Total liabilities	6,596,000,000		6,131,000,000
Commitments and contingencies	0		0
Preferred securities	87,000,000		87,000,000
Shareholders' equity
Common stock	2,379,000,000		2,379,000,000
Retained earnings	598,000,000		559,000,000
Accumulated other comprehensive income (loss), net	1,000,000		0
Total shareholders' equity	2,978,000,000		2,938,000,000
Total liabilities and shareholders' equity	9,661,000,000		9,156,000,000
Member's equity
Accumulated other comprehensive income (loss), net	1,000,000		0
PECO Energy Co [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	0		0
Deferred credits and other liabilities
Regulatory liabilities	0		0
PECO Energy Co [Member] | Customer Rate Credit [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	121,000,000		49,000,000		51,000,000	50,000,000
Restricted cash and investments of variable interest entity	49,000,000		30,000,000
Accounts receivable, net
Customer	358,000,000		428,000,000
Other	120,000,000		90,000,000
Income taxes receivable	61,000,000		21,000,000
Inventories, net
Fossil fuel	53,000,000		74,000,000
Materials and supplies	34,000,000		34,000,000
Prepaid utility taxes	85,000,000		56,000,000
Regulatory assets	189,000,000		174,000,000
Other	8,000,000		12,000,000
Total current assets	1,078,000,000		968,000,000
Property, plant and equipment, net	5,378,000,000		5,132,000,000
Deferred debits and other assets
Regulatory assets	534,000,000		550,000,000
Investments	5,000,000
Investments in affiliates	8,000,000		8,000,000
Prepaid pension asset	477,000,000		514,000,000
Other	24,000,000		29,000,000
Total deferred debits and other assets	1,048,000,000		1,101,000,000
Total assets	7,504,000,000		7,201,000,000
Current liabilities
Long-term debt due within one year	400,000,000		110,000,000
Long-term debt of variable interest entities due within one year	65,000,000		63,000,000
Accounts payable	190,000,000		210,000,000
Accrued expenses	125,000,000		148,000,000
Payables to affiliates	44,000,000		41,000,000
Deferred income taxes	56,000,000		59,000,000
Customer deposits	75,000,000		84,000,000
Regulatory liabilities	22,000,000		18,000,000
Other	71,000,000		25,000,000
Total current liabilities	1,048,000,000		758,000,000
Long-term debt	1,446,000,000		1,596,000,000
Long-term debt of variable interest entities	258,000,000		258,000,000
Long-term debt of variable interest entity	299,000,000		332,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,598,000,000		1,491,000,000
Asset retirement obligations	8,000,000		1,000,000
Non-pension postretirement benefit obligations	208,000,000		212,000,000
Regulatory liabilities	212,000,000		200,000,000
Other	84,000,000		52,000,000
Total deferred credits and other liabilities	2,110,000,000		1,956,000,000
Total liabilities	5,161,000,000		4,900,000,000
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,360,000,000		1,294,000,000
Retained earnings	793,000,000		817,000,000
Accumulated other comprehensive income (loss), net	0		0
Total shareholders' equity	2,153,000,000		2,111,000,000
BGE preference stock not subject to mandatory redemption	190,000,000		190,000,000
Total equity	2,343,000,000		2,301,000,000
Total liabilities and shareholders' equity	7,504,000,000		7,201,000,000
Member's equity
Accumulated other comprehensive income (loss), net	0		0
Baltimore Gas and Electric Company [Member] | Removal Costs [Member]
Current liabilities
Regulatory liabilities	21,000,000		18,000,000
Deferred credits and other liabilities
Regulatory liabilities	212,000,000		200,000,000
Baltimore Gas and Electric Company [Member] | Customer Rate Credit [Member]
Current liabilities
Regulatory liabilities	1,000,000
Deferred credits and other liabilities
Regulatory liabilities	$ 0

[1] Current and noncurrent assets are shown net of collateral of $92 million and $263 million, respectively, and current and noncurrent liabilities are shown net of collateral of $(49) million and $(113) million, respectively. The total cash collateral received, net of cash collateral posted and offset against mark-to-market assets and liabilities was $193 million at September 30, 2012.

[2] Current and noncurrent assets are shown net of collateral of $338 million and $187 million, respectively, and current and noncurrent liabilities are shown inclusive of collateral of $15 million and $0 million, respectively. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $540 million at December 31, 2011.