Consolidated Balance Sheets (Unaudited) (USD $)	Dec. 31, 2011		Dec. 31, 2010
Current assets
Cash and cash equivalents	$ 1,016,000,000		$ 1,612,000,000
Restricted cash and investments	40,000,000		30,000,000
Accounts receivable, net
Customer	1,613,000,000		1,932,000,000
Other	1,000,000,000		1,196,000,000
Mark-to-market derivative assets	432,000,000		487,000,000
Mark-to-market derivative assets with affiliates	0
Inventories, net
Fossil fuel	208,000,000		216,000,000
Materials and supplies	656,000,000		590,000,000
Deferred income taxes	97,000,000		0
Regulatory assets	69,000,000		10,000,000
Other	358,000,000		325,000,000
Total current assets	5,489,000,000		6,398,000,000
Property, plant and equipment, net	32,570,000,000		29,941,000,000
Deferred debits and other assets
Regulatory assets	4,839,000,000		4,140,000,000
Nuclear decommissioning trust funds	6,507,000,000		6,408,000,000
Investments	751,000,000		717,000,000
Investments in affiliates	15,000,000		15,000,000
Goodwill	2,625,000,000		2,625,000,000
Mark-to-market derivative assets	650,000,000		409,000,000
Mark-to-market derivative assets with affiliates	0
Pledged assets for Zion Station decommissioning	734,000,000		824,000,000
Other	912,000,000		763,000,000
Total deferred debits and other assets	17,033,000,000		15,901,000,000
Total assets	55,092,000,000		52,240,000,000
Current liabilities
Short-term borrowings	163,000,000		0
Short-term notes payable - accounts receivable agreement	225,000,000		225,000,000
Long-term debt due within one year	828,000,000		599,000,000
Accounts payable	1,444,000,000		1,373,000,000
Accrued expenses	1,255,000,000		1,040,000,000
Payables to affiliates	5,000,000		5,000,000
Deferred income taxes	0		85,000,000
Regulatory liabilities	53,000,000		44,000,000
Mark-to-market derivative liabilities	112,000,000		38,000,000
Dividends payable	349,000,000		1,000,000
Other	560,000,000		835,000,000
Total current liabilities	4,989,000,000		4,240,000,000
Long-term debt	11,799,000,000		11,614,000,000
Long-term debt to financing trusts	390,000,000		390,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	8,351,000,000		6,621,000,000
Asset retirement obligations	3,884,000,000		3,494,000,000
Pension obligations	2,194,000,000		3,658,000,000
Non-pension postretirement benefit obligations	2,263,000,000		2,218,000,000
Spent nuclear fuel obligation	1,019,000,000		1,018,000,000
Regulatory liabilities	3,771,000,000		3,555,000,000
Mark-to-market derivative liabilities	126,000,000		21,000,000
Payable for Zion Station decommissioning	563,000,000		659,000,000
Other	1,268,000,000		1,102,000,000
Total deferred credits and other liabilities	23,439,000,000		22,346,000,000
Total liabilities	40,617,000,000		38,590,000,000
Commitments and contingencies	0		0
Preferred securities	87,000,000		87,000,000
Shareholders' equity
Common stock	9,107,000,000		9,006,000,000
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	10,055,000,000		9,304,000,000
Accumulated other comprehensive income (loss), net	(2,450,000,000)		(2,423,000,000)
Total shareholders' equity	14,385,000,000		13,560,000,000
Noncontrolling interest	3,000,000		3,000,000
Total equity	14,388,000,000		13,563,000,000
Total liabilities and shareholders' equity	55,092,000,000		52,240,000,000
Member's equity
Accumulated other comprehensive income (loss), net	(2,450,000,000)		(2,423,000,000)
Noncontrolling interest	3,000,000		3,000,000
Exelon Generation Co L L C [Member]
Current assets
Cash and cash equivalents	496,000,000		456,000,000
Restricted cash and cash equivalents	5,000,000		1,000,000
Accounts receivable, net
Customer	578,000,000		469,000,000
Other	257,000,000		161,000,000
Mark-to-market derivative assets	432,000,000	[1]	487,000,000	[2]
Mark-to-market derivative assets with affiliates	503,000,000	[1]	455,000,000	[2]
Receivables from affiliates	109,000,000		306,000,000
Inventories, net
Fossil fuel	120,000,000		129,000,000
Materials and supplies	556,000,000		500,000,000
Other	148,000,000		123,000,000
Total current assets	3,204,000,000		3,087,000,000
Property, plant and equipment, net	13,475,000,000		11,662,000,000
Deferred debits and other assets
Nuclear decommissioning trust funds	6,507,000,000		6,408,000,000
Investments	41,000,000		35,000,000
Receivable from affiliate	1,000,000		1,000,000
Mark-to-market derivative assets	635,000,000		391,000,000
Mark-to-market derivative assets with affiliates	191,000,000	[1]	525,000,000	[2]
Prepaid pension asset	2,068,000,000		1,236,000,000
Pledged assets for Zion Station decommissioning	734,000,000		824,000,000
Other	577,000,000		365,000,000
Total deferred debits and other assets	10,754,000,000		9,785,000,000
Total assets	27,433,000,000		24,534,000,000
Current liabilities
Short-term borrowings	2,000,000
Long-term debt due within one year	3,000,000		3,000,000
Accounts payable	753,000,000		749,000,000
Accrued expenses	779,000,000		391,000,000
Payables to affiliates	58,000,000		47,000,000
Deferred income taxes	244,000,000		427,000,000
Mark-to-market derivative liabilities	103,000,000	[1]	34,000,000	[2]
Other	202,000,000		192,000,000
Total current liabilities	2,144,000,000		1,843,000,000
Long-term debt	3,674,000,000		3,676,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	3,966,000,000		3,318,000,000
Asset retirement obligations	3,767,000,000		3,357,000,000
Non-pension postretirement benefit obligations	703,000,000		692,000,000
Spent nuclear fuel obligation	1,019,000,000		1,018,000,000
Payables to affiliates	2,222,000,000		2,267,000,000
Mark-to-market derivative liabilities	29,000,000		21,000,000
Payable for Zion Station decommissioning	563,000,000		659,000,000
Other	638,000,000		506,000,000
Total deferred credits and other liabilities	12,907,000,000		11,838,000,000
Total liabilities	18,725,000,000		17,357,000,000
Commitments and contingencies	0		0
Shareholders' equity
Accumulated other comprehensive income (loss), net	915,000,000		1,013,000,000
Noncontrolling interest	5,000,000		5,000,000
Member's equity
Membership interest	3,556,000,000		3,526,000,000
Undistributed earnings	4,232,000,000		2,633,000,000
Accumulated other comprehensive income (loss), net	915,000,000		1,013,000,000
Total member's equity	8,703,000,000		7,172,000,000
Noncontrolling interest	5,000,000		5,000,000
Total equity	8,708,000,000		7,177,000,000
Total liabilities and equity	27,433,000,000		24,534,000,000
Commonwealth Edison Co [Member]
Current assets
Cash and cash equivalents	234,000,000		50,000,000
Restricted cash and cash equivalents	3,000,000		0
Accounts receivable, net
Customer	655,000,000		768,000,000
Other	385,000,000		525,000,000
Inventories, net
Inventories, net	81,000,000		72,000,000
Deferred income taxes	76,000,000		115,000,000
Counterparty collateral deposited	90,000,000		153,000,000
Regulatory assets	560,000,000		456,000,000
Other	22,000,000		12,000,000
Total current assets	2,106,000,000		2,151,000,000
Property, plant and equipment, net	13,121,000,000		12,578,000,000
Deferred debits and other assets
Regulatory assets	796,000,000		947,000,000
Investments	21,000,000		23,000,000
Investments in affiliates	6,000,000		6,000,000
Goodwill	2,625,000,000		2,625,000,000
Receivable from affiliate	1,860,000,000		1,895,000,000
Mark-to-market derivative assets	0		4,000,000
Prepaid pension asset	1,803,000,000		1,039,000,000
Other	315,000,000		384,000,000
Total deferred debits and other assets	7,426,000,000		6,923,000,000
Total assets	22,653,000,000		21,652,000,000
Current liabilities
Short-term borrowings	0		0
Long-term debt due within one year	450,000,000		347,000,000
Accounts payable	325,000,000		332,000,000
Accrued expenses	318,000,000		366,000,000
Payables to affiliates	111,000,000		398,000,000
Customer deposits	136,000,000		130,000,000
Regulatory liabilities	12,000,000		19,000,000
Mark-to-market derivative liabilities	9,000,000		0
Mark-to-market derivative liabilities with affiliate	503,000,000		450,000,000
Other	82,000,000		92,000,000
Total current liabilities	1,946,000,000		2,134,000,000
Long-term debt	5,215,000,000		4,654,000,000
Long-term debt to financing trusts	206,000,000	[3]	206,000,000
Deferred credits and other liabilities
Deferred income taxes and unamortized investment tax credits	4,008,000,000		3,308,000,000
Asset retirement obligations	89,000,000		105,000,000
Non-pension postretirement benefit obligations	271,000,000		271,000,000
Regulatory liabilities	3,167,000,000		3,137,000,000
Mark-to-market derivative liabilities	97,000,000
Mark-to-market derivative liabilities with affiliate	191,000,000		525,000,000
Other	426,000,000		402,000,000
Total deferred credits and other liabilities	8,249,000,000		7,748,000,000
Total liabilities	15,616,000,000		14,742,000,000
Commitments and contingencies	0		0
Shareholders' equity
Common stock	1,588,000,000		1,588,000,000
Other paid-in capital	5,003,000,000		4,992,000,000
Retained earnings	447,000,000		331,000,000
Accumulated other comprehensive income (loss), net	(1,000,000)		(1,000,000)
Total shareholders' equity	7,037,000,000		6,910,000,000
Total liabilities and shareholders' equity	22,653,000,000		21,652,000,000
Member's equity
Accumulated other comprehensive income (loss), net	(1,000,000)		(1,000,000)
PECO Energy Co [Member]
Current assets
Cash and cash equivalents	194,000,000		522,000,000
Restricted cash and cash equivalents	2,000,000		0
Accounts receivable, net
Customer	380,000,000		695,000,000
Other	376,000,000		277,000,000
Inventories, net
Fossil fuel	87,000,000		87,000,000
Materials and supplies	18,000,000		18,000,000
Deferred income taxes	25,000,000		41,000,000
Receivable from Exelon intercompany money pool	82,000,000		0
Regulatory assets	12,000,000		9,000,000
Other	40,000,000		21,000,000
Total current assets	1,216,000,000		1,670,000,000
Property, plant and equipment, net	5,874,000,000		5,620,000,000
Deferred debits and other assets
Regulatory assets	1,243,000,000		968,000,000
Investments	22,000,000		20,000,000
Investments in affiliates	8,000,000		8,000,000
Receivable from affiliate	365,000,000		375,000,000
Prepaid pension asset	382,000,000		281,000,000
Other	46,000,000		43,000,000
Total deferred debits and other assets	2,066,000,000		1,695,000,000
Total assets	9,156,000,000		8,985,000,000
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		250,000,000
Long-term debt to PECO Energy Transition Trust due within one year	0		0
Accounts payable	262,000,000		201,000,000
Accrued expenses	83,000,000		95,000,000
Payables to affiliates	62,000,000		275,000,000
Deferred income taxes	0		0
Customer deposits	53,000,000		65,000,000
Regulatory liabilities	41,000,000		25,000,000
Mark-to-market derivative liabilities	0		4,000,000
Mark-to-market derivative liabilities with affiliate	0		5,000,000
Other	25,000,000		18,000,000
Total current liabilities	1,126,000,000		1,163,000,000
Long-term debt	1,597,000,000		1,972,000,000
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	2,170,000,000		1,823,000,000
Asset retirement obligations	28,000,000		32,000,000
Non-pension postretirement benefit obligations	288,000,000		292,000,000
Regulatory liabilities	604,000,000		418,000,000
Mark-to-market derivative liabilities	0		0
Mark-to-market derivative liabilities with affiliate	0		0
Other	134,000,000		131,000,000
Total deferred credits and other liabilities	3,224,000,000		2,696,000,000
Total liabilities	6,131,000,000		6,015,000,000
Commitments and contingencies	0		0
Preferred securities	87,000,000		87,000,000
Shareholders' equity
Common stock	2,379,000,000		2,361,000,000
Receivable from parent	0		0
Retained earnings	559,000,000		522,000,000
Accumulated other comprehensive income (loss), net	0		0
Total shareholders' equity	2,938,000,000		2,883,000,000
Total liabilities and shareholders' equity	9,156,000,000		8,985,000,000
Member's equity
Accumulated other comprehensive income (loss), net	$ 0		$ 0

[1] 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.

[2] Current and noncurrent assets are shown net of collateral of $725 million and $199 million, respectively, and current and noncurrent liabilities are shown inclusive of collateral of $10 million and $17 million, respectively. The total cash collateral received net of cash collateral posted and offset against mark-to-market assets and liabilities was $951 million at December 31, 2010.

[3] Amount owed to this financing trust is recorded as debt to financing trust within ComEd's Consolidated Balance Sheets.