Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

9 Months Ended

Mar. 31, 2012

Sep. 30, 2011

Fair value of financial liabilities recorded at the carrying amount

		March 31, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	1,036	$	472	$	564	$	0	$	737	$	737
Long-term debt (including amounts
	due within one year)		17,545		0		18,918		162		12,627		14,488
Long-term debt to financing trusts			648		0		641		0		390		358
SNF obligation			1,019		0		882		0		1,019		886
Preferred securities of subsidiary			87		0		79		0		87		79

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

As of March 31, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents (a)	$	187	$	0	$	0	$	187
Nuclear decommissioning trust fund investments
Cash equivalents		428		0		0		428
Equity
Equity securities		1,460		0		0		1,460
Commingled funds		0		2,027		0		2,027
Equity funds subtotal		1,460		2,027		0		3,487
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		941		1		0		942
Debt securities issued by states of the United States
and political subdivisions of the states		0		328		0		328
Debt securities issued by foreign governments		0		67		0		67
Corporate debt securities		0		1,534		0		1,534
Federal agency mortgage-backed securities		0		55		0		55
Commercial mortgage-backed securities (non-agency)		0		39		0		39
Residential mortgage-backed securities (non-agency)		0		8		0		8
Mutual funds		0		2		0		2
Fixed income subtotal		941		2,034		0		2,975
Direct lending securities		0		0		13		13
Other debt obligations		0		11		0		11
Nuclear decommissioning trust fund investments subtotal(b)		2,829		4,072		13		6,914

Pledged assets for Zion Station decommissioning
Equity
Equity securities		26		0		0		26
Commingled funds		0		22		0		22
Equity funds subtotal		26		22		0		48
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		63		24		0		87
Debt securities issued by states of the United States
and political subdivisions of the states		0		53		0		53
Corporate debt securities		0		325		0		325
Federal agency mortgage-backed securities		0		100		0		100
Commercial mortgage-backed securities (non-agency)		0		10		0		10
Commingled funds		0		40		0		40
Fixed income subtotal		63		552		0		615
Direct lending securities		0		0		42		42
Pledged assets for Zion Station decommissioning subtotal(c)		89		574		42		705

Rabbi trust investments
Cash equivalents		2		0		0		2
Mutual funds(d)(e)		73		0		0		73
Rabbi trust investments subtotal		75		0		0		75

Commodity mark-to-market derivative assets
Economic hedges		1,988		6,913		990		9,891
Proprietary trading		3,341		6,427		219		9,987
Effect of netting and allocation of collateral(f)		(5,329)		(11,418)		(370)		(17,117)
Commodity mark-to-market assets subtotal(g)		0		1,922		839		2,761
Interest rate mark-to-market derivative assets		0		119		0		119
Other investments		3		0		14		17

Total assets		3,183		6,687		908		10,778

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(2,527)		(5,659)		(449)		(8,635)
Proprietary trading		(3,457)		(6,146)		(364)		(9,967)
Effect of netting and allocation of collateral(f)		5,755		10,791		333		16,879
Commodity mark-to-market liabilities subtotal(g)(h)		(229)		(1,014)		(480)		(1,723)
Interest rate mark-to-market derivative liabilities		0		(54)		0		(54)
Deferred compensation		0		(106)		0		(106)

Total liabilities		(229)		(1,174)		(480)		(1,883)

Total net assets	$	2,954	$	5,513	$	428	$	8,895

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 $13 million and $(57) million at March 31, 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 $3 million and $9 million at March 31, 2012 and December 31, 2011. 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 $60 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 $27 million and $25 million of the cash surrender value of life insurance investments at March 31, 2012 and December 31, 2011, respectively.

(f) Includes collateral postings received from counterparties. Collateral received from counterparties, net of collateral paid to counterparties, totaled $426, $(627) million and $(37) million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of March 31, 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 $590 million and $92 million at March 31, 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 $ 16 million and $125 million at March 31, 2012, respectively, and $9 million and $97 million at December 31, 2011, respectively, related to floating-to-fixed energy swap contracts with unaffiliated suppliers.

(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 $590 million and $92 million at March 31, 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 $ 16 million and $125 million at March 31, 2012, respectively, and $9 million and $97 million at December 31, 2011, respectively, related to floating-to-fixed energy swap contracts with unaffiliated suppliers.

Includes $67 million of changes in the fair value and $112 million of realized gains due to settlements associated with ComEd's financial swap with Generation. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
Includes an increase in fair value of $51 million associated with 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 March 31, 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		85	(a)		0		85
	Included in regulatory assets		-		0		(35)	(b)		0		(35)
Change in collateral			-		0		(23)			0		(23)
Purchases, sales, issuances and settlements
	Purchases (c )		-		6		316			14		336
	Sales		-		(1)		0			0		(1)
Transfers out of Level 3					-		(1)			0		(1)

Balance as of March 31, 2012		$	13	$	42	$	359		$	14	$	428
The amount of total gains included in net income
	attributed to the change in unrealized losses related to assets and liabilities held for the three months ended March 31, 2012	$	0	$	0	$	93		$	0	$	93

(a) Includes the reclassification of $19 million of realized losses due to the settlement of derivative contracts recorded in results of operations.

(b) Includes $135 million of increases in fair value and $147 million of realized losses due to settlements during 2012 of Generation's financial swap contract with ComEd, which eliminates upon consolidation in Exelon's Consolidated Financial Statements.

(c) Includes $310 million of fair value from contracts and $14 million of other investments acquired as a result of the merger.

Three Months Ended March 31, 2011		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010		$	0	$	50			50
	Included in net income		0		(13)	(a)		(13)
	Included in other comprehensive income		0		(9)	(b)		(9)
	Included in regulatory liabilities		0		52	(c)		52
Change in collateral			0		5			5
Purchases			31		0			31
Transfers out of Level 3			0		(34)			(34)

Balance as of March 31, 2011		$	31	$	51		$	82
The amount of total gains included in net income
	attributed to the change in unrealized gains related to assets and liabilities held for the three months ended March 31, 2011	$	0	$	(7)			(7)

(a) Includes the reclassification of $6 million of realized losses due to the settlement of derivative contracts recorded in results of operations.

(b) Excludes $67 million of changes in fair value and $112 million of realized losses due to settlements associated with Generation's financial swap contract with ComEd and a $1 million decrease related to the settlement of Generation's block contracts with PECO, which eliminates upon consolidation in Exelon's Consolidated Financial Statements.

(c) Includes an increase in fair value of $51 million associated with floating-to-fixed energy swap contracts with unaffiliated suppliers.

Three Months Ended March 31, 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		-		-		74	(a)		-		74
	Included in other comprehensive income		-		-		(1)	(b)		-		(1)
Change in collateral			-		-		(23)			-		(23)
Purchases, sales, issuances and settlements
	Purchases (c)		-		6		316			14		336
	Sales		-		(1)		-			-		(1)
Transfers out of Level 3			-		-		(1)			-		(1)

Balance as of March 31, 2012		$	13	$	42	$	1,182		$	14	$	1,251
The amount of total gains included in income
	attributed to the change in unrealized gains related to assets and liabilities held for the year ended March 31, 2012	$	-	$	-	$	93				$	93

Three Months Ended March 31, 2011		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010		$	0	$	1,030		$	1,030
Total realized / unrealized losses
	Included in net income		0		(13)	(a)		(13)
	Included in other comprehensive income		0		(55)	(b)		(55)
Change in collateral			0		5			5
Purchases			31		0			31
Transfers out of Level 3			0		(34)			(34)

Balance as of March 31, 2011		$	31	$	933		$	964
The amount of total losses included in income attributed to
	the change in unrealized losses related to assets and
	liabilities held for the three months ended March 31, 2011	$	0	$	(7)		$	(7)

Three Months Ended March 31, 2012	Mark-to-Market Derivatives
Balance as of December 31, 2011	$	(800)
Total realized / unrealized losses included in regulatory assets (a)(b)		(23)

Balance as of March 31, 2012	$	(823)

Three Months Ended March 31, 2011		Mark-to-Market Derivatives
Balance as of December 31, 2010		$	(971)
	Total unrealized / realized gains included in regulatory assets(a)(b)		96
Balance as of March 31, 2011		$	(875)

Three Months Ended March 31, 2011	Mark-to-Market Derivatives
Balance as of December 31, 2010	$	(9)
Total realized / unrealized gains (losses)		2	(a)

Balance as of March 31, 2011	$	(7)

(a) Includes the reclassification of $19 million of realized losses due to the settlement of derivative contracts recorded in results of operations.

(c) Includes $310 million of fair value from contracts and $14 million of other investments acquired as a result of the merger.

(a) Includes the reclassification of $6 million of realized gains due to the settlement of derivative contracts recorded in results of operations.

(b) Includes $67 million changes in fair value and $112 million of realized losses due to settlements during 2011 of Generation's financial swap contract with ComEd and $1 million of changes in the fair value of Generation's block contract with PECO, which eliminates upon consolidation in Exelon's Consolidated Financial Statements..

Includes a $1 million increase related to the settlement of PECO's block contract with Generation, which eliminates 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

Three Months Ended March 31, 2012		Operating Revenues		Purchased Power and Fuel
Total gains (losses) included in net income for the three months ended
	March 31, 2012	$	87	$	(2)
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the three months ended March 31, 2012	$	104	$	(11)

Three Months Ended March 31, 2011		Operating Revenues		Purchased Power and Fuel
Total losses included in net income for the three months ended
	March 31, 2011	$	(3)	$	(10)
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the three months ended March 31, 2011	$	4	$	(11)

Three Months Ended March 31, 2012		Operating Revenue		Purchased Power and Fuel
Total gains (losses) included in net income for the three
	months ended March 31, 2012	$	76	$	(2)
Change in the unrealized gains (losses) relating to assets and
	liabilities held for the three months ended March 31, 2012	$	104	$	(11)

Three Months Ended March 31, 2011		Operating Revenue		Purchased Power and Fuel
Total losses included in net income for the three months
	ended March 31, 2011	$	(3)	$	(10)
Change in the unrealized gains (losses) relating to assets and
	liabilities held for the three months ended March 31, 2011	$	4	$	(11)

Exelon Generation Co L L C [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		March 31, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	114	$	0	$	114	$	0	$	2	$	2
Long-term debt (including amounts
	due within one year)		6,646		0		6,804		67		3,677		4,231
SNF obligation			1,019		0		882		0		1,019		886

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

As of March 31, 2012	Level 1		Level 2		Level 3			Total
Assets
Cash equivalents (a)	$	60	$	0	$	0	$	60
Nuclear decommissioning trust fund investments
Cash equivalents		428		0		0		428
Equity
Equity securities		1,460		0		0		1,460
Commingled funds		0		2,027		0		2,027
Equity funds subtotal		1,460		2,027		0		3,487
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		941		1		0		942
Debt securities issued by states of the United States and
political subdivisions of the states		0		328		0		328
Debt securities issued by foreign governments		0		67		0		67
Corporate debt securities		0		1,534		0		1,534
Federal agency mortgage-backed securities		0		55		0		55
Commercial mortgage-backed securities (non-agency)		0		39		0		39
Residential mortgage-backed securities (non-agency)		0		8		0		8
Mutual funds		0		2		0		2
Fixed income subtotal		941		2,034		0		2,975
Direct lending securities		0		0		13		13
Other debt obligations		0		11		0		11
Nuclear decommissioning trust fund investments subtotal(b)		2,829		4,072		13		6,914

Pledged assets for Zion Station decommissioning
Equity
Equity securities		26		0		0		26
Commingled funds		0		22		0		22
Equity funds subtotal		26		22		0		48
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		63		24		0		87
Debt securities issued by states of the United States and
political subdivisions of the states		0		53		0		53
Corporate debt securities		0		325		0		325
Federal agency mortgage-backed securities		0		100		0		100
Commercial mortgage-backed securities (non-agency)		0		10		0		10
Commingled funds		0		40		0		40
Fixed income subtotal		63		552		0		615
Direct lending securities		0		0		42		42
Pledged assets for Zion Station decommissioning subtotal(c)		89		574		42		705

Rabbi trust investments(d)(e)		5		0		0		5

Commodity mark-to-market derivative assets
Economic hedges		1,988		6,913		1,672		10,573
Proprietary trading		3,341		6,427		219		9,987
Effect of netting and allocation of collateral(f)		(5,329)		(11,418)		(370)		(17,117)
Commodity mark-to-market assets subtotal(g)		0		1,922		1,521		3,443
Interest Rate mark-to-market derivative assets		0		105		0		105
Other investments		3		0		14		17

Total assets		2,986		6,673		1,590		11,249

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(2,527)		(5,659)		(308)		(8,494)
Proprietary trading		(3,457)		(6,146)		(364)		(9,967)
Effect of netting and allocation of collateral(f)		5,755		10,791		333		16,879
Commodity mark-to-market liabilities subtotal		(229)		(1,014)		(339)		(1,582)
Interest rate mark-to-market derivative liabilities		0		(54)		0		(54)
Deferred compensation		0		(20)		0		(20)

Total liabilities		(229)		(1,088)		(339)		(1,656)

Total net assets	$	2,757	$	5,585	$	1,251	$	9,593

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 $3 million and $9 million at March 31, 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 are classified as Level 1 as they are valued based upon quoted prices (unadjusted) in active markets.

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

(g) The Level 3 balance includes current and noncurrent assets for Generation of $590 million and $92 million at March 31, 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.

Commonwealth Edison Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		March 31, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	302	$	0	$	302	$	0	$	0	$	0
Long-term debt (including amounts
	due within one year)		5,215		0		6,067		18		5,665		6,540
Long-term debt to financing trust			206		0		206		0		206		184

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

As of March 31, 2012		Level 1		Level 2		Level 3		Total
Assets
Cash equivalents (a)		$	3	$	0	$	0	$	3
Rabbi trust investments
Cash equivalents			1		0		0		1
Mutual funds			15		0		0		15
	Rabbi trust investment subtotal		16		0		0		16

Total assets			19		0		0		19

Liabilities
Deferred compensation obligation			0		(9)		0		(9)
Mark-to-market derivative liabilities (b)(c)			0		0		(823)		(823)

Total liabilities			0		(9)		(823)		(832)

Total net assets (liabilities)		$	19	$	(9)	$	(823)	$	(813)

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.

PECO Energy Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		March 31, 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)		1,972		0		2,291		0		1,972		2,295
Long-term debt to financing trusts			184		0		176		0		184		174
Preferred securities			87		0		79		0		87		79

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

As of March 31, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	53	$	0	$	0	$	53
Rabbi trust investments - mutual funds(b)(c)		9		0		0		9

Total assets		62		0		0		62

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

Total liabilities		0		(21)		0		(21)

Total net assets (liabilities)	$	62	$	(21)	$	0	$	41

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 March 31, 2012 and December 31, 2011, respectively.

Baltimore Gas and Electric Company [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		March 31, 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)		2,101		-	2,359	-		2,101		2,377
Long-term debt to financing trusts			258		-	259	-		258		256

- 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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