Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2012		Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 721,000,000		$ 1,016,000,000
Restricted cash and cash equivalents of variable interest entity	67,000,000
Restricted cash and investments	43,000,000		40,000,000
Accounts receivable, net
Customer	2,868,000,000		1,613,000,000
Other	1,339,000,000		1,000,000,000
Accounts receivable of variable interest entities	241,000,000
Mark-to-market derivative assets	1,491,000,000		432,000,000
Mark-to-market derivative assets with affiliates	0		0
Unamortized energy contracts assets	1,699,000,000		13,000,000
Inventories, net
Fossil fuel	202,000,000		208,000,000
Materials and supplies	740,000,000		656,000,000
Deferred income taxes	0		0
Regulatory assets	846,000,000		390,000,000
Other	1,558,000,000		345,000,000
Total current assets	11,815,000,000		5,713,000,000
Property, plant and equipment, net	42,105,000,000		32,570,000,000
Deferred debits and other assets
Regulatory assets	6,168,000,000		4,518,000,000
Nuclear decommissioning trust funds	6,927,000,000		6,507,000,000
Investments	827,000,000		751,000,000
Investments in affiliates	362,000,000		15,000,000
Investment in CENG	2,046,000,000		0
Goodwill	2,625,000,000		2,625,000,000
Mark-to-market derivative assets	1,389,000,000		650,000,000
Mark-to-market derivative assets with affiliates	0		0
Unamortized energy contracts assets	1,530,000,000		388,000,000
Pledged assets for Zion Station decommissioning	708,000,000		734,000,000
Other	1,126,000,000		524,000,000
Total deferred debits and other assets	23,708,000,000		16,712,000,000
Total assets	77,628,000,000		54,995,000,000
Current liabilities
Short-term borrowings	339,000,000		163,000,000
Short-term notes payable - accounts receivable agreement	225,000,000		225,000,000
Long-term debt due within one year	670,000,000		828,000,000
Long-term debt of variable interest entities due within one year	65,000,000		0
Accounts payable	2,125,000,000		1,444,000,000
Accounts payable of variable interest entities	138,000,000		0
Accrued expenses	1,492,000,000		1,255,000,000
Deferred income taxes	517,000,000		1,000,000
Regulatory liabilities	335,000,000		197,000,000
Mark-to-market derivative liabilities	1,105,000,000		112,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	707,000,000		0
Dividends payable	472,000,000		349,000,000
Other	862,000,000		560,000,000
Total current liabilities	9,052,000,000		5,134,000,000
Long-term debt	16,293,000,000		11,799,000,000
Long-term debt to financing trusts	648,000,000		390,000,000
Long-term debt of variable interest entity	517,000,000		0
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	10,705,000,000		8,253,000,000
Asset retirement obligations	4,064,000,000		3,884,000,000
Pension obligations	2,553,000,000		2,194,000,000
Non-pension postretirement benefit obligations	2,688,000,000		2,263,000,000
Spent nuclear fuel obligation	1,019,000,000		1,019,000,000
Regulatory liabilities	4,050,000,000		3,627,000,000
Mark-to-market derivative liabilities	671,000,000		126,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	897,000,000		0
Payable for Zion Station decommissioning	574,000,000		563,000,000
Other	1,708,000,000		1,268,000,000
Total deferred credits and other liabilities	28,929,000,000		23,197,000,000
Total liabilities	55,439,000,000		40,520,000,000
Commitments and contingencies	0		0
Preferred securities	87,000,000		87,000,000
Shareholders' equity
Common stock	16,512,000,000		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	9,830,000,000		10,055,000,000
Accumulated other comprehensive income (loss), net	(2,199,000,000)		(2,450,000,000)
BGE preference stock not subject to mandatory redemption	193,000,000		0
Total shareholders' equity	21,816,000,000		14,385,000,000
Noncontrolling interest	93,000,000		3,000,000
Total equity	22,102,000,000		14,388,000,000
Total liabilities and shareholders' equity	77,628,000,000		54,995,000,000
Member's equity
Accumulated other comprehensive income (loss), net	(2,199,000,000)		(2,450,000,000)
Noncontrolling interest	93,000,000		3,000,000
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	219,000,000		496,000,000
Restricted cash and cash equivalents	3,000,000		5,000,000
Restricted cash and cash equivalents of variable interest entity	18,000,000
Accounts receivable, net
Customer	1,520,000,000		578,000,000
Other	404,000,000		257,000,000
Accounts receivable of variable interest entities	241,000,000
Mark-to-market derivative assets with affiliates	590,000,000	[1]	503,000,000	[2]
Unamortized energy contracts assets	1,699,000,000		13,000,000
Receivables from affiliates	142,000,000		109,000,000
Inventories, net
Fossil fuel	132,000,000		120,000,000
Materials and supplies	602,000,000		556,000,000
Other	1,180,000,000		148,000,000
Total current assets	8,241,000,000		3,217,000,000
Property, plant and equipment, net	17,480,000,000		13,475,000,000
Deferred debits and other assets
Nuclear decommissioning trust funds	6,927,000,000		6,507,000,000
Investments	70,000,000		41,000,000
Investments in affiliates	340,000,000		1,000,000
Investment in CENG	2,046,000,000		0
Mark-to-market derivative assets	1,375,000,000		635,000,000
Mark-to-market derivative assets with affiliates	92,000,000	[1]	191,000,000	[2]
Unamortized energy contracts assets	1,530,000,000		388,000,000
Prepaid pension asset	2,098,000,000		2,068,000,000
Pledged assets for Zion Station decommissioning	708,000,000		734,000,000
Other	816,000,000		176,000,000
Total deferred debits and other assets	16,002,000,000		10,741,000,000
Total assets	41,723,000,000		27,433,000,000
Current liabilities
Short-term borrowings	114,000,000		2,000,000
Long-term debt due within one year	72,000,000		3,000,000
Accounts payable	1,229,000,000		753,000,000
Accounts payable of variable interest entities	138,000,000		0
Accrued expenses	894,000,000		779,000,000
Payables to affiliates	183,000,000		58,000,000
Deferred income taxes	758,000,000		244,000,000
Mark-to-market derivative liabilities	1,090,000,000		103,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	590,000,000		0
Other	360,000,000		202,000,000
Total current liabilities	5,428,000,000		2,144,000,000
Long-term debt	6,388,000,000		3,674,000,000
Long-term debt of variable interest entity	186,000,000		0
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,899,000,000		3,966,000,000
Asset retirement obligations	3,939,000,000		3,767,000,000
Non-pension postretirement benefit obligations	778,000,000		703,000,000
Spent nuclear fuel obligation	1,019,000,000		1,019,000,000
Payables to affiliates	2,430,000,000		2,222,000,000
Mark-to-market derivative liabilities	546,000,000		29,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Unamortized energy contract liabilities	808,000,000		0
Payable for Zion Station decommissioning	574,000,000		563,000,000
Other	839,000,000		638,000,000
Total deferred credits and other liabilities	15,832,000,000		12,907,000,000
Total liabilities	27,834,000,000		18,725,000,000
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	1,167,000,000		915,000,000
Noncontrolling interest	94,000,000		5,000,000
Member's equity
Membership interest	8,828,000,000		3,556,000,000
Undistributed earnings	3,800,000,000		4,232,000,000
Accumulated other comprehensive income (loss), net	1,167,000,000		915,000,000
Total member's equity	13,795,000,000		8,703,000,000
Noncontrolling interest	94,000,000		5,000,000
Total equity	13,889,000,000		8,708,000,000
Total liabilities and equity	41,723,000,000		27,433,000,000
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	19,000,000		234,000,000
Restricted cash and cash equivalents	3,000,000		3,000,000
Accounts receivable, net
Customer	596,000,000		655,000,000
Other	272,000,000		385,000,000
Inventories, net
Inventories, net	84,000,000		81,000,000
Deferred income taxes	62,000,000		61,000,000
Counterparty collateral deposited	98,000,000		90,000,000
Regulatory assets	793,000,000		657,000,000
Other	21,000,000		22,000,000
Total current assets	1,948,000,000		2,188,000,000
Property, plant and equipment, net	13,267,000,000		13,121,000,000
Deferred debits and other assets
Regulatory assets	644,000,000		699,000,000
Investments	16,000,000		21,000,000
Investments in affiliates	6,000,000		6,000,000
Goodwill	2,625,000,000		2,625,000,000
Receivable from affiliate	2,020,000,000		1,860,000,000
Mark-to-market derivative assets	0		0
Prepaid pension asset	1,772,000,000		1,803,000,000
Other	291,000,000		315,000,000
Total deferred debits and other assets	7,374,000,000		7,329,000,000
Total assets	22,589,000,000		22,638,000,000
Current liabilities
Short-term borrowings	302,000,000		0
Long-term debt due within one year	0		450,000,000
Accounts payable	277,000,000		325,000,000
Accrued expenses	204,000,000		318,000,000
Payables to affiliates	125,000,000		111,000,000
Customer deposits	138,000,000		136,000,000
Regulatory liabilities	127,000,000		137,000,000
Mark-to-market derivative liabilities with affiliate	590,000,000		503,000,000
Other	69,000,000		82,000,000
Total current liabilities	1,848,000,000		2,071,000,000
Long-term debt	5,215,000,000		5,215,000,000
Long-term debt to financing trusts	206,000,000		206,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,042,000,000		3,993,000,000
Asset retirement obligations	90,000,000		89,000,000
Non-pension postretirement benefit obligations	301,000,000		271,000,000
Regulatory liabilities	3,208,000,000		3,042,000,000
Mark-to-market derivative liabilities	125,000,000		97,000,000
Mark-to-market derivative liabilities with affiliate	92,000,000		191,000,000
Other	403,000,000		426,000,000
Total deferred credits and other liabilities	8,261,000,000		8,109,000,000
Total liabilities	15,530,000,000		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	5,012,000,000		5,003,000,000
Retained earnings	459,000,000		447,000,000
Accumulated other comprehensive income (loss), net	0		(1,000,000)
Total shareholders' equity	7,059,000,000		7,037,000,000
Total liabilities and shareholders' equity	22,589,000,000		22,638,000,000
Member's equity
Accumulated other comprehensive income (loss), net	0		(1,000,000)
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	148,000,000		194,000,000
Restricted cash and cash equivalents	5,000,000		2,000,000
Accounts receivable, net
Customer	333,000,000		380,000,000
Other	293,000,000		376,000,000
Inventories, net
Fossil fuel	46,000,000		87,000,000
Materials and supplies	20,000,000		18,000,000
Deferred income taxes	28,000,000		25,000,000
Receivable from Exelon intercompany money pool	117,000,000		82,000,000
Prepaid utility taxes	130,000,000		1,000,000
Regulatory assets	48,000,000		39,000,000
Other	43,000,000		39,000,000
Total current assets	1,211,000,000		1,243,000,000
Property, plant and equipment, net	5,924,000,000		5,874,000,000
Deferred debits and other assets
Regulatory assets	1,217,000,000		1,216,000,000
Investments	23,000,000		22,000,000
Investments in affiliates	8,000,000		8,000,000
Receivable from affiliate	413,000,000		365,000,000
Prepaid pension asset	381,000,000		382,000,000
Other	38,000,000		46,000,000
Total deferred debits and other assets	2,080,000,000		2,039,000,000
Total assets	9,215,000,000		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	213,000,000		262,000,000
Accrued expenses	78,000,000		83,000,000
Payables to affiliates	75,000,000		62,000,000
Customer deposits	52,000,000		53,000,000
Regulatory liabilities	73,000,000		60,000,000
Mark-to-market derivative liabilities with affiliate	0		0
Other	22,000,000		25,000,000
Total current liabilities	1,113,000,000		1,145,000,000
Long-term debt	1,597,000,000		1,597,000,000
Long-term debt to financing trusts	184,000,000		184,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	2,193,000,000		2,170,000,000
Asset retirement obligations	28,000,000		28,000,000
Non-pension postretirement benefit obligations	295,000,000		288,000,000
Regulatory liabilities	637,000,000		585,000,000
Other	133,000,000		134,000,000
Total deferred credits and other liabilities	3,286,000,000		3,205,000,000
Total liabilities	6,180,000,000		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	568,000,000		559,000,000
Accumulated other comprehensive income (loss), net	1,000,000		0
Total shareholders' equity	2,948,000,000		2,938,000,000
Total liabilities and shareholders' equity	9,215,000,000		9,156,000,000
Member's equity
Accumulated other comprehensive income (loss), net	1,000,000		0
Baltimore Gas and Electric Company [Member]
Current assets
Cash and cash equivalents	157,000,000		49,000,000
Restricted cash and cash equivalents of variable interest entity	49,000,000		30,000,000
Accounts receivable, net
Customer	419,000,000		428,000,000
Other	95,000,000		90,000,000
Income taxes receivable	77,000,000		21,000,000
Inventories, net
Fossil fuel	24,000,000		74,000,000
Materials and supplies	34,000,000		34,000,000
Prepaid utility taxes	27,000,000		56,000,000
Regulatory assets	174,000,000		174,000,000
Other	10,000,000		12,000,000
Total current assets	1,066,000,000		968,000,000
Property, plant and equipment, net	5,211,000,000		5,132,000,000
Deferred debits and other assets
Regulatory assets	553,000,000		550,000,000
Investments in affiliates	8,000,000		8,000,000
Prepaid pension asset	504,000,000		514,000,000
Other	27,000,000		33,000,000
Total deferred debits and other assets	1,092,000,000		1,105,000,000
Total assets	7,369,000,000		7,205,000,000
Current liabilities
Long-term debt due within one year	110,000,000		110,000,000
Long-term debt of variable interest entities due within one year	63,000,000		63,000,000
Accounts payable	167,000,000		210,000,000
Accrued expenses	113,000,000		148,000,000
Payables to affiliates	102,000,000		41,000,000
Deferred income taxes	23,000,000		59,000,000
Customer deposits	82,000,000		84,000,000
Regulatory liabilities	135,000,000		18,000,000
Regulatory liabilities	22,000,000
Residential customer rate credit regulatory liability	113,000,000
Other	45,000,000		25,000,000
Total current liabilities	840,000,000		758,000,000
Long-term debt	1,596,000,000		1,596,000,000
Long-term debt to financing trusts	258,000,000		258,000,000
Long-term debt of variable interest entity	332,000,000		332,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	1,569,000,000		1,491,000,000
Asset retirement obligations	8,000,000		1,000,000
Non-pension postretirement benefit obligations	211,000,000		212,000,000
Regulatory liabilities	205,000,000		200,000,000
Other	82,000,000		56,000,000
Total deferred credits and other liabilities	2,075,000,000		1,960,000,000
Total liabilities	5,101,000,000		4,904,000,000
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,294,000,000		1,294,000,000
Retained earnings	784,000,000		817,000,000
Accumulated other comprehensive income (loss), net	0		0
BGE preference stock not subject to mandatory redemption	190,000,000		190,000,000
Total shareholders' equity	2,078,000,000		2,111,000,000
Total equity	2,268,000,000		2,301,000,000
Total liabilities and shareholders' equity	7,369,000,000		7,205,000,000
Member's equity
Accumulated other comprehensive income (loss), net	$ 0		$ 0

[1] Current and noncurrent assets are shown net of collateral of $281 million and $400 million, respectively, and current and noncurrent liabilities are shown inclusive of collateral of $(212) million and $(231) million, respectively. The total cash collateral received, net of cash collateral posted and offset against mark-to-market assets and liabilities was $238 million at March 31, 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.