Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2012

Fair value of financial liabilities recorded at the carrying amount

		September 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	289	$	4	$	285	$	0	$	737	$	737
Long-term debt (including amounts
	due within one year)		18,715		0		20,762		38		12,627		14,488
Long-term debt to financing trusts			649		0		650		0		390		358
SNF obligation			1,020		0		780		0		1,019		886
Preferred securities of subsidiary			87		0		83		0		87		79

Assets and liabilities measured and recorded at fair value on recurring basis

As of September 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	1,117	$	0	$	0	$	1,117
Nuclear decommissioning trust fund investments
Cash equivalents		319		0		0		319
Equity
Equity securities		1,452		0		0		1,452
Commingled funds		0		1,906		0		1,906
Equity funds subtotal		1,452		1,906		0		3,358
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		1,100		0		0		1,100
Debt securities issued by states of the United States
and political subdivisions of the states		0		355		0		355
Debt securities issued by foreign governments		0		84		0		84
Corporate debt securities		0		1,734		0		1,734
Federal agency mortgage-backed securities		0		31		0		31
Commercial mortgage-backed securities (non-agency)		0		47		0		47
Residential mortgage-backed securities (non-agency)		0		15		0		15
Mutual funds		0		9		0		9
Fixed income subtotal		1,100		2,275		0		3,375
Direct lending securities		0		0		70		70
Other debt obligations		0		16		0		16
Nuclear decommissioning trust fund investments subtotal(b)		2,871		4,197		70		7,138

Pledged assets for Zion Station decommissioning
Equity
Equity securities		21		0		0		21
Commingled funds		0		20		0		20
Equity funds subtotal		21		20		0		41
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		78		15		0		93
Debt securities issued by states of the United States
and political subdivisions of the states		0		58		0		58
Corporate debt securities		0		260		0		260
Federal agency mortgage-backed securities		0		60		0		60
Commercial mortgage-backed securities (non-agency)		0		6		0		6
Commingled funds		0		43		0		43
Fixed income subtotal		78		442		0		520
Direct lending securities		0		0		64		64
Other debt obligations		0		1		0		1
Pledged assets for Zion Station decommissioning subtotal(c)		99		463		64		626

Rabbi trust investments
Cash equivalents		2		0		0		2
Mutual funds(d)(e)		69		0		0		69
Rabbi trust investments subtotal		71		0		0		71

Commodity mark-to-market derivative assets
Economic hedges		994		3,872		666		5,532
Proprietary trading		1,631		3,070		140		4,841
Effect of netting and allocation of collateral(f)		(2,597)		(5,695)		(238)		(8,530)
Commodity mark-to-market assets subtotal(g)		28		1,247		568		1,843
Interest rate mark-to-market derivative assets		0		125		0		125
Other investments		2		0		17		19

Total assets		4,188		6,032		719		10,939

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(1,225)		(2,814)		(351)		(4,390)
Proprietary trading		(1,678)		(2,881)		(222)		(4,781)
Effect of netting and allocation of collateral(f)		2,772		5,336		229		8,337
Commodity mark-to-market liabilities subtotal(g)(h)		(131)		(359)		(344)		(834)
Interest rate mark-to-market derivative liabilities		0		(95)		0		(95)
Deferred compensation		0		(101)		0		(101)

Total liabilities		(131)		(555)		(344)		(1,030)

Total net assets	$	4,057	$	5,477	$	375	$	9,909

As of December 31, 2011	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents(a)	$	861	$	0	$	0	$	861
Nuclear decommissioning trust fund investments
Cash equivalents		562		0		0		562
Equity
Equity securities		1,275		0		0		1,275
Commingled funds		0		1,822		0		1,822
Equity funds subtotal		1,275		1,822		0		3,097
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		1,014		33		0		1,047
Debt securities issued by states of the United States
and political subdivisions of the states		0		541		0		541
Debt securities issued by foreign governments		0		16		0		16
Corporate debt securities		0		778		0		778
Federal agency mortgage-backed securities		0		357		0		357
Commercial mortgage-backed securities (non-agency)		0		83		0		83
Residential mortgage-backed securities (non-agency)		0		5		0		5
Mutual funds		0		47		0		47
Fixed income subtotal		1,014		1,860		0		2,874
Direct lending securities		0		0		13		13
Other debt obligations		0		18		0		18
Nuclear decommissioning trust fund investments subtotal(b)		2,851		3,700		13		6,564

Pledged assets for Zion decommissioning
Equity
Equity securities		35		0		0		35
Commingled funds		0		30		0		30
Equity funds subtotal		35		30		0		65
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		54		26		0		80
Debt securities issued by states of the United States
and political subdivisions of the states		0		65		0		65
Corporate debt securities		0		314		0		314
Federal agency mortgage-backed securities		0		121		0		121
Commercial mortgage-backed securities (non-agency)		0		10		0		10
Commingled funds		0		20		0		20
Fixed income subtotal		54		556		0		610
Direct lending securities		0		0		37		37
Other debt obligations		0		13		0		13
Pledged assets for Zion Station decommissioning subtotal(c)		89		599		37		725

Rabbi trust investments
Cash equivalents		2		0		0		2
Mutual funds(d)(e)		34		0		0		34
Rabbi trust investments subtotal		36		0		0		36

Commodity mark-to-market derivative assets
Cash flow hedges		0		857		0		857
Economic hedges		0		1,653		124		1,777
Proprietary trading		0		240		48		288
Effect of netting and allocation of collateral(f)		0		(1,827)		(28)		(1,855)
Commodity mark-to-market assets(g)		0		923		144		1,067
Interest rate mark-to-market derivative assets		0		15		0		15

Total assets		3,837		5,237		194		9,268

Liabilities
Commodity mark-to-market derivative liabilities
Cash flow hedges		0		(13)		0		(13)
Economic hedges		(1)		(1,137)		(119)		(1,257)
Proprietary trading		0		(236)		(28)		(264)
Effect of netting and allocation of collateral(f)		0		1,295		20		1,315
Commodity mark-to-market liabilities (h)		(1)		(91)		(127)		(219)
Interest rate mark-to-market liabilities		0		(19)		0		(19)
Deferred compensation		0		(73)		0		(73)

Total liabilities		(1)		(183)		(127)		(311)

Total net assets	$	3,836	$	5,054	$	67	$	8,957

(a) Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b) Excludes net assets (liabilities) of $2 million and $(57) million at September 30, 2012 and December 31, 2011, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.

(c) Excludes net assets of $5 million and $9 million at September 30, 2012 and December 31, 2011, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.

(d) The mutual funds held by the Rabbi trusts include $54 million related to deferred compensation and $15 million related to Supplemental Executive Retirement Plan. These funds are classified as Level 1 as they are valued based upon quoted prices (unadjusted) in active markets.

(e) Excludes $28 million and $25 million of the cash surrender value of life insurance investments at September 30, 2012 and December 31, 2011, respectively.

(f) Includes collateral postings (received) from counterparties. Collateral (received) from counterparties, net of collateral paid to counterparties, totaled $175 million, $(359) million and $(9) million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of September 30, 2012. Collateral (received) from counterparties, net of collateral paid to counterparties, totaled $532 million and $8 million allocated to Level 2 and Level 3 mark-to-market derivatives, respectively, as of December 31, 2011.

(g) The Level 3 balance does not include current and noncurrent assets for Generation and current and noncurrent liabilities for ComEd of $352 million and $0 million at September 30, 2012 and $503 million and $191 million at December 31, 2011, respectively, related to the fair value of Generation's financial swap contract with ComEd.

(h) The Level 3 balance includes the current and noncurrent liability of $17 million and $53 million at September 30, 2012, respectively, and $9 million and $97 million at December 31, 2011, respectively, related to floating-to-fixed energy swap contracts with unaffiliated suppliers.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis

Three Months Ended September 30, 2012		Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Other Investments		Total
Balance as of June 30, 2012		$	54	$	59	$	295		$	17	$	425
Total realized / unrealized gains (losses)
	Included in net income		0		0		(97)	(a)		0		(97)
	Included in regulatory assets		2		0		41	(b)		0		43
	Included in payable for Zion Station decommissioning		0		1		0			0		1
Change in collateral			0		-		(15)			0		(15)
Purchases, sales, issuances and settlements
	Purchases (c)		14		4		-			0		18

Balance as of September 30, 2012		$	70	$	64	$	224		$	17	$	375
The amount of total losses included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the three months ended September 30, 2012	$	0	$	0	$	(42)		$	0	$	(42)

Nine Months Ended September 30, 2012		Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Other Investments		Total
Balance as of December 31, 2011		$	13	$	37	$	17		$	0	$	67
Total realized / unrealized gains (losses)
	Included in net income		0		0		(157)	(a)		0		(157)
	Included in other comprehensive income		0		0		1			0		1
	Included in regulatory assets		2		0		36	(b)		0		38
Change in collateral			0		0		(7)			0		(7)
Purchases, sales, issuances and settlements
	Purchases (c)		55		36		329			17		437
	Sales		0		(9)		0			0		(9)
Transfers into Level 3			0		0		(34)			0		(34)
Transfers out of Level 3			0		0		39			0		39

Balance as of September 30, 2012		$	70	$	64	$	224		$	17	$	375
The amount of total losses included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the nine months ended September 30, 2012	$	0	$	0	$	(16)		$	0	$	(16)

(a) Includes the reclassification of $55 million and $141 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2012.

(b) Excludes $35 million of decreases in fair value and $86 million of increases in fair value and $119 million and $427 million of realized losses due to settlements for the three and nine months ended September 30, 2012 of Generation's financial swap contract with ComEd, which eliminates upon consolidation in Exelon's Consolidated Financial Statements.

(c) Includes $323 million of fair value from contracts and $17 million of other investments acquired as a result of the merger.

Three Months Ended September 30, 2011			Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of June 30, 2011			$	0	$	34	$	(16)		$	18
Total realized / unrealized gains (losses)
	Included in income			0		0		(8)	(a)		(8)
	Included in other comprehensive income			0		0		(15)	(b)		(15)
	Included in regulatory assets			0		0		(18)			(18)
	Included in payable for Zion Station decommissioning			0		(3)		0			(3)
Change in collateral				0		0		8			8
Purchases, sales, issuances and settlements
	Purchases			6		17		0			23
	Sales			0		(10)		0			(10)
Transfers out of Level 3				0		0		24			24
Balance as of September 30, 2011			$	6	$	38	$	(25)		$	19
The amount of total gains included in income attributed to
	the change in unrealized losses related to assets and liabilities held for the three months ended September 30, 2011		$	0	$	0	$	(5)		$	-5

Nine Months Ended September 30, 2011		Nuclear Decommissioning Trust Fund Investments			Pledged Assets for Zion Decommissioning		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010			$	0	$	0	$	50		$	50
Total realized / unrealized gains (losses)
	Included in other comprehensive income			0		0		(27)	(a)		(27)
	Included in regulatory assets			0		0		(51)	(b)		(51)
Change in collateral				0		0		15			15
Purchases, sales, issuances and settlements
	Purchases			6		60		4			70
	Sales			0		(22)		0			(22)
Transfers out of Level 3				0		0		(16)			(16)
Balance as of September 30, 2011			$	6	$	38	$	(25)		$	19
The amount of total gains included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the nine months ended September 30, 2011		$	0	$	0	$	18		$	18

(a) Includes the reclassification of $4 million and $19 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2011, respectively.

(b) Excludes $7 million and $4 million of decreases in fair value and $88 million and $309 million of realized losses due to settlements associated with Generation's financial swap contract with ComEd and $3 million of changes in the fair value of Generation's block contracts with PECO for the nine months ended September 30, 2011. All items eliminate upon consolidation if Exelon's Consolidated Financial Statements.

Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis


		Operating Revenue		Purchased Power and Fuel
Total gains (losses) included in income for the three months ended
	September 30, 2012	$	(106)	$	9
Total gains (losses) included in income for the nine months ended
	September 30, 2012	$	(195)	$	38
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the three months ended September 30, 2012	$	(48)	$	6
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the nine months ended September 30, 2012	$	(45)	$	29

		Operating Revenue		Purchased Power and Fuel
Total gains (losses) included in income for the three months ended
	September 30, 2011	$	(5)	$	(3)
Total gains (losses) included in income for the nine months ended
	September 30, 2011	$	2	$	(2)
Change in the unrealized gains (losses) relating to assets and liabilities held
	for the three months ended September 30, 2011	$	1	$	(6)
Change in the unrealized gains (losses) relating to assets and liabilities held
	for the nine months ended September 30, 2011	$	22	$	(4)

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis, valuation technique

Type of trade	Fair Value at September 30, 2012 (d)		Valuation Technique	Unobservable Input	Range
Mark-to-market derivatives – Economic Hedges (Generation) (a)	$	386	Discounted Cash Flow	Forward power price	$	8		-	$	76
			Discounted Cash Flow	Forward gas price	$	3.04		-	$	6.35
			Option Model	Volatility percentage		26	%	-		120	%

Mark-to-market derivatives – Proprietary trading (Generation) (a)	$	(83)	Discounted Cash Flow	Forward power price	$	13		-	$	108
			Option Model	Volatility percentage		22	%	-		67	%

Mark-to-market derivatives – Transactions with affiliates (Generation and ComEd) (b)	$	352	Discounted Cash Flow	Marketability reserve		7.3	%	-		8.7	%

Mark-to-market derivatives (ComEd)	$	(70)	Discounted Cash Flow	Forward heat rate (c)		8.5	%	-		9.5	%
				Marketability reserve		3.5	%	-		8.3	%
				Renewable factor		80	%	-		126	%

The valuation techniques, unobservable inputs and ranges are the same for the asset and liability positions.
Includes current assets for Generation and current liabilities for ComEd of $352 million, related to the fair value of the five-year financial swap contract between Generation and ComEd, which eliminates in consolidation.
Quoted forward natural gas rates are utilized to project the forward power curve for the delivery of energy at specified future dates. The natural gas curve is extrapolated beyond its observable period to the end of the contract's delivery.
The fair values below do not include cash collateral held on level three positions of $9 million as of September 30, 2012.

Exelon Generation Co L L C [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		September 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	11	$	0	$	11	$	0	$	2	$	2
Long-term debt (including amounts
	due within one year)		7,383		0		7,839		20		3,677		4,231
SNF obligation			1,020		0		780		0		1,019		886

Assets and liabilities measured and recorded at fair value on recurring basis

As of September 30, 2012	Level 1		Level 2		Level 3			Total
Assets
Cash equivalents	$	518	$	0	$	0	$	518
Nuclear decommissioning trust fund investments
Cash equivalents		319		0		0		319
Equity
Equity securities		1,452		0		0		1,452
Commingled funds		0		1,906		0		1,906
Equity funds subtotal		1,452		1,906		0		3,358
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		1,100		0		0		1,100
Debt securities issued by states of the United States and
political subdivisions of the states		0		355		0		355
Debt securities issued by foreign governments		0		84		0		84
Corporate debt securities		0		1,734		0		1,734
Federal agency mortgage-backed securities		0		31		0		31
Commercial mortgage-backed securities (non-agency)		0		47		0		47
Residential mortgage-backed securities (non-agency)		0		15		0		15
Mutual funds		0		9		0		9
Fixed income subtotal		1,100		2,275		0		3,375
Direct lending securities		0		0		70		70
Other debt obligations		0		16		0		16
Nuclear decommissioning trust fund investments subtotal(b)		2,871		4,197		70		7,138

Pledged assets for Zion Station decommissioning
Equity
Equity securities		21		0		0		21
Commingled funds		0		20		0		20
Equity funds subtotal		21		20		0		41
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		78		15		0		93
Debt securities issued by states of the United States and
political subdivisions of the states		0		58		0		58
Corporate debt securities		0		260		0		260
Federal agency mortgage-backed securities		0		60		0		60
Commercial mortgage-backed securities (non-agency)		0		6		0		6
Commingled funds		0		43		0		43
Fixed income subtotal		78		442		0		520
Direct lending securities		0		0		64		64
Other debt obligations		0		1		0		1
Pledged assets for Zion Station decommissioning subtotal(c)		99		463		64		626

Rabbi trust investments
Cash equivalents		1		0		0		1
Mutual funds (d) (e)		13		0		0		13
Rabbi trust investments subtotal		14		0		0		14

Commodity mark-to-market derivative assets
Economic hedges		994		3,872		1,018		5,884
Proprietary trading		1,631		3,070		140		4,841
Effect of netting and allocation of collateral(f)		(2,597)		(5,695)		(238)		(8,530)
Commodity mark-to-market assets subtotal(g)		28		1,247		920		2,195
Interest Rate mark-to-market derivative assets		0		111		0		111
Other investments		2		0		17		19

Total assets		3,532		6,018		1,071		10,621

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(1,225)		(2,814)		(281)		(4,320)
Proprietary trading		(1,678)		(2,881)		(222)		(4,781)
Effect of netting and allocation of collateral(f)		2,772		5,336		229		8,337
Commodity mark-to-market liabilities subtotal		(131)		(359)		(274)		(764)
Interest rate mark-to-market derivative liabilities		0		(95)		0		(95)
Deferred compensation		0		(27)		0		(27)

Total liabilities		(131)		(481)		(274)		(886)

Total net assets	$	3,401	$	5,537	$	797	$	9,735

As of December 31, 2011	Level 1		Level 2		Level 3			Total
Assets
Cash equivalents(a)	$	466	$	0	$	0	$	466
Nuclear decommissioning trust fund investments
Cash equivalents		562		0		0		562
Equity
Equity securities		1,275		0		0		1,275
Commingled funds		0		1,822		0		1,822
Equity funds subtotal		1,275		1,822		0		3,097
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		1,014		33		0		1,047
Debt securities issued by states of the United States and
political subdivisions of the states		0		541		0		541
Debt securities issued by foreign governments		0		16		0		16
Corporate debt securities		0		778		0		778
Federal agency mortgage-backed securities		0		357		0		357
Commercial mortgage-backed securities (non-agency)		0		83		0		83
Residential mortgage-backed securities (non-agency)		0		5		0		5
Mutual funds		0		47		0		47
Fixed income subtotal		1,014		1,860		0		2,874
Direct lending securities		0		0		13		13
Other debt obligations		0		18		0		18
Nuclear decommissioning trust fund investments subtotal(b)		2,851		3,700		13		6,564

Pledged assets for Zion Station decommissioning
Equity
Equity securities		35		0		0		35
Commingled funds		0		30		0		30
Equity funds subtotal		35		30		0		65
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		54		26		0		80
Debt securities issued by states of the United States and
political subdivisions of the states		0		65		0		65
Corporate debt securities		0		314		0		314
Federal agency mortgage-backed securities		0		121		0		121
Commercial mortgage-backed securities (non-agency)		0		10		0		10
Commingled funds		0		20		0		20
Fixed income subtotal		54		556		0		610
Direct lending securities		0		0		37		37
Other debt obligations		0		13		0		13
Pledged assets for Zion Station decommissioning subtotal(c)		89		599		37		725

Rabbi trust investments(d)(e)		4		0		0		4

Commodity mark-to-market derivative assets
Cash flow hedges		0		857		694		1,551
Other derivatives		0		1,653		124		1,777
Proprietary trading		0		240		48		288
Effect of netting and allocation of collateral(f)		0		(1,827)		(28)		(1,855)
Commodity mark-to-market assets subtotal(g)		0		923		838		1,761

Total assets		3,410		5,222		888		9,520

Liabilities
Commodity mark-to-market derivative liabilities
Cash flow hedges		0		(13)		0		(13)
Other derivatives		(1)		(1,137)		(13)		(1,151)
Proprietary trading		0		(236)		(28)		(264)
Effect of netting and allocation of collateral(f)		0		1,295		20		1,315
Commodity mark-to-market liabilities subtotal		(1)		(91)		(21)		(113)
Interest rate mark-to-market derivative liabilities		0		(19)		0		(19)
Deferred compensation		0		(18)		0		(18)

Total liabilities		(1)		(128)		(21)		(150)

Total net assets	$	3,409	$	5,094	$	867	$	9,370

(a) Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(c) Excludes net assets of $5 million and $9 million at September 30, 2012 December 31, 2011, respectively. These items consist of receivables related to pending securities sales, interest and dividend receivables, and payables related to pending securities purchases.

(d) The $13 million mutual funds held by the Rabbi trusts are classified as Level 1 as they are valued based upon quoted prices (unadjusted) in active markets.

(e) Excludes $8 million and $7 million of the cash surrender value of life insurance investments at September 30, 2012 and December 31, 2011, respectively.

(g) The Level 3 balance includes current and noncurrent assets for Generation of $352 million and $0 million at September 30, 2012 and $503 million and $191 million at December 31, 2011, respectively, related to the fair value of Generation's financial swap contract with ComEd, which eliminates upon consolidation in Exelon's Consolidated Financial Statements.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis

Three Months Ended September 30, 2012		Nuclear Decommissioning Trust Fund Investments			Pledged Assets for Zion Station Decommissioning	Mark-to-Market Derivatives				Other Investments	Total
Balance as of June 30, 2012		$	54	$	59	$	912			17	$	1,042
Total unrealized / realized gains (losses)
	Included in income		-		-		(112)	(a)		-		(112)
	Included in other comprehensive income		-		-		(139)	(b)		-		(139)
	Included in noncurrent payables to affiliates		2		-		-			-		2
	Included in payable for Zion Station decommissioning		-		1		-			-		1
Change in collateral			-		-		(15)			-		(15)
Purchases, sales, issuances and settlements
	Purchases (c)		14		4		-			-		18

Balance as of September 30, 2012		$	70	$	64	$	646		$	17	$	797
The amount of total losses included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the three months ended September 30, 2012	$	-	$	-	$	(77)		$	-	$	(77)

Nine Months Ended September 30, 2012		Nuclear Decommissioning Trust Fund Investments			Pledged Assets for Zion Station Decommissioning	Mark-to-Market Derivatives				Other Investments	Total
Balance as of December 31, 2011		$	13	$	37	$	817			-	$	867
Total unrealized / realized gains (losses)
	Included in income		-		-		(187)	(a)		-		(187)
	Included in other comprehensive income		-		-		(311)	(b)		-		(311)
	Included in noncurrent payables to affiliates		2		-		-			-		2
Change in collateral			-		-		(7)			-		(7)
Purchases, sales, issuances and settlements
	Purchases (c)		55		36		329			17		437
	Sales		-		(9)		-			-		(9)
Transfers into Level 3			-		-		(34)					(34)
Transfers out of Level 3			-		-		39			-		39

Balance as of September 30, 2012		$	70	$	64	$	646		$	17	$	797
The amount of total losses included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the nine months ended September 30, 2012	$	-	$	-	$	(77)		$	-	$	(77)

(a) Includes the reclassification of $35 million and $110 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and nine months ended September 30, 2012, respectively.

(b) Includes $35 million of decreases in fair value and $86 million of increases in fair value and realized losses due to settlements of $119 million and $427 million associated with Generation's financial swap contract with ComEd for the three and nine months ended September 30, 2012, respectively. This position was de-designated as a cash flow hedge prior to the merger date. All prospective changes in fair value and reclassifications of realized amounts are being recorded to income offset by the amortization of the frozen mark in OCI. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.

(c) Includes $323 million of fair value from contracts and $17 million of other investments acquired as a result of the merger.

Three Months Ended September 30, 2011		Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of June 30, 2011		$	0	$	34	$	776		$	810
Total realized / unrealized gains (losses)
	Included in income		0		0		(8)	(a)		(8)
	Included in other comprehensive income		0		0		(110)	(b)		(110)
	Included in payable for Zion Station decommissioning		0		(3)		0			(3)
Changes in collateral			0		0		8			8
Purchases, sales, issuances and settlements
	Purchases		6		17		0			23
	Sales		0		(10)		0			(10)
Transfers out of Level 3 - Asset			0		0		24			24

Balance as of September 30, 2011		$	6	$	38	$	690		$	734

The amount of total gains included in income attributed to
	the change in unrealized (losses) related to assets and liabilities held for the three months ended September 30, 2011	$	0	$	0	$	(5)		$	(5)

Nine Months Ended September 30, 2011		Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010		$	0	$	0	$	1,030		$	1,030
Total realized / unrealized gains (losses)
	Included in other comprehensive income		0		0		(343)	(b)		(343)
Changes in collateral			0		0		15			15
	Purchases		6		60		4			70
	Sales		0		(22)		0			(22)
Transfers out of Level 3 - Liability			0		0		(16)			(16)

Balance as of September 30, 2011		$	6	$	38	$	690		$	734

The amount of total gains included in income attributed to
	the change in unrealized gains related to assets and liabilities held for the nine months ended September 30, 2011	$	0	$	0	$	18		$	18

(b) Includes $7 million and $4 million of decreases in fair value realized losses reclassified from OCI due to settlements of $88 million and $309 million associated with Generation's financial swap contract with ComEd for the three and nine months ended September 30, 2011, and $3 million of decreases in fair value due to settlement of Generation's block contracts with PECO for the three and nine months ended September 30, 2011. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.

Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis

		Operating Revenue		Purchased Power and Fuel
Total gains (losses) included in income for the three months ended September 30, 2012		$	(121)	$	9
Total gains (losses) included in income for the nine months ended
	September 30, 2012	$	(225)	$	38
Change in the unrealized gains (losses) relating to assets and liabilities held for
	the three months ended September 30, 2012	$	(83)	$	6
Change in the unrealized gains (losses) relating to assets and liabilities held for
	the nine months ended September 30, 2012	$	(95)	$	18

		Operating Revenue		Purchased Power and Fuel
Total gains (losses) included in income for the three months ended
	September 30, 2011	$	(5)	$	(3)
Total gains (losses) included in income for the nine months ended September 30, 2011		$	2	$	(2)
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the three months ended September 30, 2011	$	1	$	(6)
Change in the unrealized gains (losses) relating to assets and liabilities held for
	the nine months ended September 30, 2011	$	22	$	(4)

Commonwealth Edison Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		September 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	35	$	0	$	35	$	0	$	0	$	0
Long-term debt (including amounts
	due within one year)		5,217		0		6,297		18		5,665		6,540
Long-term debt to financing trust			206		0		208		0		206		184

Assets and liabilities measured and recorded at fair value on recurring basis

As of September 30, 2012		Level 1		Level 2		Level 3		Total
Assets
Rabbi trust investments
Mutual funds			9		0		0		9
	Rabbi trust investment subtotal		9		0		0		9

Total assets			9		0		0		9

Liabilities
Deferred compensation obligation			0		(9)		0		(9)
Mark-to-market derivative liabilities (b)(c)			0		0		(422)		(422)

Total liabilities			0		(9)		(422)		(431)

Total net assets (liabilities)		$	9	$	(9)	$	(422)	$	(422)

As of December 31, 2011		Level 1		Level 2		Level 3		Total
Assets
Cash equivalents (a)		$	173	$	0	$	0	$	173
Rabbi trust investments
Cash equivalents			2		0		0		2
Mutual funds			19		0		0		19
	Rabbi trust investment subtotal		21		0		0		21

Total assets			194		0		0		194

Liabilities
Deferred compensation obligation			0		(8)		0		(8)
Mark-to-market derivative liabilities (b)(c)			0		0		(800)		(800)

Total liabilities			0		(8)		(800)		(808)

Total net assets (liabilities)		$	194	$	(8)	$	(800)	$	(614)

(a) Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b) The Level 3 balance includes the current and noncurrent liability of $352 million and $0 million at September 30, 2012, respectively, and $503 million and $191 million at December 31, 2011, respectively, related to the fair value of ComEd's financial swap contract with Generation which eliminates upon consolidation in Exelon's Consolidated Financial Statements.

(c) The Level 3 balance includes the current and noncurrent liability of $17 million and $53 million at September 30, 2012, respectively, and $9 million and $97 million at December 31, 2011, respectively, related to floating-to-fixed energy swap contracts with unaffiliated suppliers.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis

Three Months Ended September 30, 2012	Mark-to-Market Derivatives
Balance as of June 30, 2012	$	(617)
Total realized / unrealized gains included in regulatory assets (a)(b)		195
Balance as of September 30, 2012	$	(422)

Nine Months Ended September 30, 2012	Mark-to-Market Derivatives
Balance as of December 31, 2011	$	(800)
Total realized / unrealized gains included in regulatory assets (a)(b)		378
Balance as of September 30, 2012	$	(422)

(a) Includes $35 million of increases in fair value and $86 million of decreases in fair value and realized gains due to settlements of $119 million and $427 million associated with ComEd's financial swap contract with Generation for the three and nine months ended September 30, 2012, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.

(b) Includes $40 million and $33 million of increases in the fair value and realized losses due to settlements of $1 million and $2 million recorded in purchased power expense associated with floating-to-fixed energy swap contracts with unaffiliated suppliers for the three and nine months ended September 30, 2012, respectively.

Three Months Ended September 30, 2011	Mark-to-Market Derivatives
Balance as of June 30, 2011	$	(788)
Total realized / unrealized gains included in regulatory assets (a)(b)		76
Balance as of September 30, 2011	$	(712)

Nine Months Ended September 30, 2011	Mark-to-Market Derivatives
Balance as of December 31, 2010	$	(971)
Total realized / unrealized gains included in regulatory assets (a)(b)		259
Balance as of September 30, 2011	$	(712)

Total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis

Includes $7 million and $4 million of increases in fair value and $88 million and $309 million of realized gains due to settlements associated with ComEd's financial swap contract with Generation for the three and nine months ended September 30, 2011, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
Includes $19 million and $54 million of decreases in fair value of floating-to-fixed energy swap contracts with unaffiliated suppliers for the three and nine months ended September 30, 2011, respectively.

PECO Energy Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		September 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	225	$	0	$	225	$	0	$	225	$	225
Long-term debt (including amounts
	due within one year)		2,322		0		2,682		0		1,972		2,295
Long-term debt to financing trusts			184		0		180		0		184		174
Preferred securities			87		0		83		0		87		79

Assets and liabilities measured and recorded at fair value on recurring basis

As of September 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	528	$	0	$	0	$	528
Rabbi trust investments - mutual funds(b)(c)		9		0		0		9

Total assets		537		0		0		537

Liabilities
Deferred compensation obligation		0		(18)		0		(18)

Total liabilities		0		(18)		0		(18)

Total net assets (liabilities)	$	537	$	(18)	$	0	$	519

As of December 31, 2011	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents(a)	$	175	$	0	$	0	$	175
Rabbi trust investments - mutual funds(b)(c)		9		0		0		9

Total assets		184		0		0		184

Liabilities
Deferred compensation obligation		0		(21)		0		(21)

Total liabilities		0		(21)		0		(21)

Total net assets (liabilities)	$	184	$	(21)	$	0	$	163

(a) Excludes certain cash equivalents considered to be held-to-maturity and not reported at fair value.

(b) The mutual funds held by the Rabbi trusts are classified as Level 1 as they are valued based upon quoted prices (unadjusted) in active markets.

(c) Excludes $14 million and $13 million of the cash surrender value of life insurance investments at September 30, 2012 and December 31, 2011, respectively.

Fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis

Three Months Ended September 30, 2011	Mark-to-Market Derivatives
Balance as of June 30, 2011	$	(4)
Total realized gains included in regulatory assets		1
Balance as of September 30, 2011	$	(3)

Nine Months Ended September 30, 2011	Mark-to-Market Derivatives
Balance as of December 31, 2010	$	(9)
Total realized gains included in regulatory assets		6	(a)
Balance as of September 30, 2011	$	(3)

(a) Includes an increase of $3 million related to the settlement of PECO's block contract with Generation for the nine months ended September 30, 2011, which eliminate upon consolidation in Exelon's Consolidated Financial Statements.

Baltimore Gas and Electric Company [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		September 30, 2012						December 31, 2011
		Carrying		Fair Value				Carrying		Fair
		Amount			Level 1	Level 2	Level 3	Amount		Value
Long-term debt (including amounts
	due within one year)		2,210		0	2,547	0		2,101		2,377
Long-term debt to financing trusts			258		0	264	0		258		256

Assets and liabilities measured and recorded at fair value on recurring basis

As of September 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	52	$	0	$	0	$	52
Rabbi trust investments - mutual funds		5		0		0		5

Total assets		57		0		0		57

Liabilities
Deferred compensation obligation		0		(5)		0		(5)

Total liabilities		0		(5)		0		(5)

Total net assets (liabilities)	$	57	$	(5)	$	0	$	52

As of December 31, 2011	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	33	$	0	$	0	$	33

Total assets		33		0		0		33

Liabilities


Total net assets (liabilities)	$	33	$	0	$	0	$	33

- Definition

Tabular disclosure of the total amount of gains or losses for the period which are included in earnings or resulted in a change to net assets which gains or losses have arisen from the use of significant unobservable inputs (Level 3) to measure the fair value of assets and liabilities. Such gains or losses are attributable to the change in unrealized gains or losses relating to those assets and liabilities so valued which are still held at the reporting date and which change are also considered for disclosure; it may be expected that a description of where those unrealized gains or losses are reported in the statement of income or the statement of financial position would also be disclosed.

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- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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