Fair Value of Financial Assets and Liabilities (Tables)

6 Months Ended

Jun. 30, 2012

Fair value of financial liabilities recorded at the carrying amount

		June 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	605	$	4	$	601	$	0	$	737	$	737
Long-term debt (including amounts
	due within one year)		18,115		0		19,554		113		12,627		14,488
Long-term debt to financing trusts			649		0		653		0		390		358
SNF obligation			1,019		0		839		0		1,019		886
Preferred securities of subsidiary			87		0		82		0		87		79

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

As of June 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	936	$	0	$	0	$	936
Nuclear decommissioning trust fund investments
Cash equivalents		320		0		0		320
Equity
Equity securities		1,362		0		0		1,362
Commingled funds		0		1,798		0		1,798
Equity funds subtotal		1,362		1,798		0		3,160
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		1,115		0		0		1,115
Debt securities issued by states of the United States
and political subdivisions of the states		0		342		0		342
Debt securities issued by foreign governments		0		73		0		73
Corporate debt securities		0		1,631		0		1,631
Federal agency mortgage-backed securities		0		43		0		43
Commercial mortgage-backed securities (non-agency)		0		39		0		39
Residential mortgage-backed securities (non-agency)		0		12		0		12
Mutual funds		0		8		0		8
Fixed income subtotal		1,115		2,148		0		3,263
Direct lending securities		0		0		54		54
Other debt obligations		0		14		0		14
Nuclear decommissioning trust fund investments subtotal(b)		2,797		3,960		54		6,811

Pledged assets for Zion Station decommissioning
Equity
Equity securities		20		0		0		20
Commingled funds		0		18		0		18
Equity funds subtotal		20		18		0		38
Fixed income
Debt securities issued by the U.S. Treasury and other
U.S. government corporations and agencies		79		17		0		96
Debt securities issued by states of the United States
and political subdivisions of the states		0		60		0		60
Corporate debt securities		0		278		0		278
Federal agency mortgage-backed securities		0		83		0		83
Commercial mortgage-backed securities (non-agency)		0		7		0		7
Commingled funds		0		28		0		28
Fixed income subtotal		79		473		0		552
Direct lending securities		0		0		59		59
Other debt obligations		0		1		0		1
Pledged assets for Zion Station decommissioning subtotal(c)		99		492		59		650

Rabbi trust investments
Cash equivalents		2		0		0		2
Mutual funds(d)(e)		72		0		0		72
Rabbi trust investments subtotal		74		0		0		74

Commodity mark-to-market derivative assets
Economic hedges		1,414		5,425		821		7,660
Proprietary trading		2,121		4,720		183		7,024
Effect of netting and allocation of collateral(f)		(3,710)		(8,423)		(261)		(12,394)
Commodity mark-to-market assets subtotal(g)		(175)		1,722		743		2,290
Interest rate mark-to-market derivative assets		0		120		0		120
Other investments		2		0		17		19

Total assets		3,733		6,294		873		10,900

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(1,807)		(4,194)		(418)		(6,419)
Proprietary trading		(2,171)		(4,500)		(298)		(6,969)
Effect of netting and allocation of collateral(f)		3,978		7,825		268		12,071
Commodity mark-to-market liabilities subtotal(g)(h)		0		(869)		(448)		(1,317)
Interest rate mark-to-market derivative liabilities		0		(89)		0		(89)
Deferred compensation		0		(97)		0		(97)

Total liabilities		0		(1,055)		(448)		(1,503)

Total net assets	$	3,733	$	5,239	$	425	$	9,397

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 $30 million and $(57) million at June 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 $9 million at 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 $57 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 June 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 $268 million, $(598) million and $7 million allocated to Level 1, Level 2 and Level 3 mark-to-market derivatives, respectively, as of June 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 $506 million and $0 million at June 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 $19 million and $92 million at June 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.

(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 $506 million and $0 million at June 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 $19 million and $92 million at June 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.

As of June 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	25	$	0	$	0	$	25
Rabbi trust investments - mutual funds		5		0		0		5

Total assets		30		0		0		30

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

Total liabilities		0		(5)		0		(5)

Total net assets (liabilities)	$	30	$	(5)	$	0	$	25

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

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

Three Months Ended June 30, 2012		Nuclear Decommissioning Trust Fund Investments		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Other Investments		Total
Balance as of March 31, 2012		$	13	$	42	$	359		$	14	$	428
Total realized / unrealized gains (losses)
	Included in net income		0		0		(67)	(a)		0		(67)
	Included in regulatory assets		0		0		30	(b)		0		30
	Included in payable for Zion Station decommissioning		0		(1)		0			0		(1)
Change in collateral			0		0		4			0		4
Purchases, sales, issuances and settlements
	Purchases (c)		41		26		0			3		70
	Sales		0		(8)		0			0		(8)
Transfers into Level 3			0		0		(34)			0		(34)
Transfers out of Level 3			0		0		3			0		3

Balance as of June 30, 2012		$	54	$	59	$	295		$	17	$	425
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 June 30, 2012	$	0	$	0	$	(1)		$	0	$	(1)

Six Months Ended June 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
	Included in net income		0		0		18	(a)		0		18
	Included in other comprehensive income		0		0		0			0		0
	Included in regulatory assets		0		0		(5)	(b)		0		(5)
	Included in payable for Zion Station decommissioning		0		(1)		0			0		(1)
Change in collateral			0		0		(19)			0		(19)
Purchases, sales, issuances and settlements
	Purchases		41		32		316	(c)		17		406
	Sales		0		(9)		0			0		(9)
Transfers into Level 3			0		0		(34)			0		(34)
Transfers out of Level 3			0		0		2			0		2

Balance as of June 30, 2012		$	54	$	59	$	295		$	17	$	425
The amount of total gains included in income
	attributed to the change in unrealized losses related to assets and liabilities held for the six months ended June 30, 2012	$	0	$	0	$	103		$	0	$	103

(a) Includes the reclassification of $66 million and $85 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2012.

(b) Excludes $14 million and $121 million of decreases in fair value and $161 million and $308 million of realized losses due to settlements for the three and six months ended June 30, 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 June 30, 2011		Pledged Assets for Zion Station Decommissioning		Mark-to-Market Derivatives			Total
Balance as of March 31, 2011		$	31	$	51		$	82
Total realized / unrealized gains (losses)
	Included in income		0		21	(a)		21
	Included in other comprehensive income		0		(3)	(b)		(3)
	Included in regulatory assets				(85)			(85)
	Included in payable for Zion Station decommissioning		3		0			3
Change in collateral			0		2			2
Purchases, sales, issuances and settlements
	Purchases		12		5			17
	Sales		(12)		0			(12)
Transfers out of Level 3 - Asset			0		(7)			(7)
Balance as of June 30, 2011		$	34	$	(16)		$	18
The amount of total gains included in income attributed to
	the change in unrealized gains (losses) related to assets and liabilities held for the three months ended June 30, 2011	$	0	$	30		$	30

Six Months Ended June 30, 2011		Pledged Assets for Zion Decommissioning		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010		$	0	$	50		$	50
Total realized / unrealized gains (losses)
	Included in income		0		8	(a)		8
	Included in other comprehensive income		0		(12)	(b)		(12)
	Included in regulatory assets		0		(33)			(33)
	Included in payable for Zion Station decommissioning		3		0			3
Change in collateral			0		7			7
Purchases, sales, issuances and settlements
	Purchases		43		5			48
	Sales		(12)		0			(12)
Transfers out of Level 3 - Asset			0		(41)			(41)
Balance as of June 30, 2011		$	34	$	(16)		$	18
The amount of total gains included in income
	attributed to the change in unrealized gains (losses) related to assets and liabilities held for the six months ended June 30, 2011	$	0	$	23		$	23

(a) Includes the reclassification of $9 million and $15 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2011, respectively.

(b) Excludes $65 million of decreases and $2 million of increases in fair value and $108 million and $220 million of realized losses due to settlements associated with Generation's financial swap contract with ComEd and $2 million and $3 million of changes in the fair value of Generation's block contracts with PECO for the three months and six months ended June 30, 2011, respectively. All items eliminate upon consolidation if Exelon's Consolidated Financial Statements.

Three Months Ended June 30, 2012		Nuclear Decommissioning Trust Fund Investments			Pledged Assets for Zion Station Decommissioning	Mark-to-Market Derivatives				Other Investments	Total
Balance as of March 31, 2012		$	13	$	42	$	1,182			14	$	1,251
Total unrealized / realized gains (losses)
	Included in income		-		-		(71)	(a)		-		(71)
	Included in other comprehensive income		-		-		(172)	(b)		-		(172)
	Included in payable for Zion Station decommissioning		-		(1)		-			-		(1)
Change in collateral			-		-		4			-		4
Purchases, sales, issuances and settlements
	Purchases (c)		41		26		-			3		70
	Sales		-		(8)		-			-		(8)
Transfers into Level 3			-		-		(34)					(34)
Transfers out of Level 3			-		-		3			-		3

Balance as of June 30, 2012		$	54	$	59	$	912		$	17	$	1,042
The amount of total losses included in income
	attributed to the change in unrealized gains related to assets and liabilities held for the three months ended June 30, 2012	$	-	$	-	$	(15)		$	-	$	(15)

Six Months Ended June 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		-		-		3	(a)		-		3
	Included in other comprehensive income		-		-		(173)	(b)		-		(173)
	Included in payable for Zion Station decommissioning		-		(1)		-			-		(1)
Change in collateral			-		-		(19)			-		(19)
Purchases, sales, issuances and settlements
	Purchases (c)		41		32		316			17		406
	Sales		-		(9)		-			-		(9)
Transfers into Level 3			-		-		(34)					(34)
Transfers out of Level 3			-		-		2			-		2

Balance as of June 30, 2012		$	54	$	59	$	912		$	17	$	1,042
The amount of total gains included in income
	attributed to the change in unrealized gains related to assets and liabilities held for the six months ended June 30, 2012	$	-	$	-	$	78		$	-	$	78

(a) Includes the reclassification of $56 million and $75 million of realized losses due to the settlement of derivative contracts recorded in results of operations for the three and six months ended June 30, 2012, respectively.

(b) Includes $14 million of decreases in fair value and $121 million of increases in fair value and realized losses due to settlements of $161 million and $308 million associated with Generation's financial swap contract with ComEd for the three and six months ended June 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 $310 million of fair value from contracts and $14 million of other investments acquired as a result of the merger.

(b) Includes $65 million of decreases in fair value and $2 million of increases in fair value realized losses reclassified from OCI due to settlements of $108 million and $220 million associated with Generation's financial swap contract with ComEd and $2 million and $3 million of decreases in fair value due to settlement of Generation's block contracts with PECO for the three and six months ended June 30, 2011, respectively. 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
	June 30, 2012	$	(96)	$	29
Total gains (losses) included in income for the six months ended
	June 30, 2012	$	(9)	$	27
Change in the unrealized gains (losses) relating to assets and liabilities
	held for the three months ended June 30, 2012	$	(22)	$	21
Change in the unrealized gains relating to assets and liabilities
	held for the six months ended June 30, 2012	$	93	$	10

		Operating Revenue		Purchased Power and Fuel
Total gains included in income for the three months ended
	June 30, 2011	$	10	$	11
Total gains (losses) included in income for the six months ended
	June 30, 2011	$	7	$	1
Change in the unrealized gains relating to assets and liabilities held
	for the three months ended June 30, 2011	$	17	$	13
Change in the unrealized gains relating to assets and liabilities
	for the six months ended June 30, 2011	$	21	$	2

Includes $65 million of increases in fair value and $2 million of decreases in fair value and $108 million and $220 million of realized gains due to settlements associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2011, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.
Includes $86 million and $35 million of decreases in fair value of floating-to-fixed energy swap contracts with unaffiliated suppliers for the three and six months ended June 30, 2011, respectively.

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 June 30, 2012		Valuation Technique	Unobservable Input	Range
Mark-to-market derivatives – Economic Hedges (Generation) (a)			Discounted Cash Flow	Forward power price	$	9		-	$	67
	$	514	Discounted Cash Flow	Forward gas price	$	2.75		-	$	7.46
			Option Model	Volatility percentage		25	%	-		304	%
Mark-to-market derivatives – Proprietary trading (Generation) (a)	$	(115)	Discounted Cash Flow	Forward power price	$	15		-	$	75
			Option Model	Volatility percentage		22	%	-		59	%
Mark-to-market derivatives – Transactions with affiliates (Generation and ComEd) (b)	$	506	Discounted Cash Flow	Marketability reserve		7.9	%	-		9.5	%
Mark-to-market derivatives (ComEd)			Discounted Cash Flow	Forward heat rate (c)		8	%	-		9.5	%
	$	(111)		Marketability reserve		3.5	%	-		8.3	%
				Renewable factor		88	%	-		125	%

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 $506 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.

Exelon Generation Co L L C [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		June 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	10	$	0	$	10	$	0	$	2	$	2
Long-term debt (including amounts
	due within one year)		7,369		0		7,451		95		3,677		4,231
SNF obligation			1,019		0		839		0		1,019		886

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

As of June 30, 2012	Level 1		Level 2		Level 3			Total
Assets
Cash equivalents	$	706	$	0	$	0	$	706
Nuclear decommissioning trust fund investments
Cash equivalents		320		0		0		320
Equity
Equity securities		1,362		0		0		1,362
Commingled funds		0		1,798		0		1,798
Equity funds subtotal		1,362		1,798		0		3,160
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		1,115		0		0		1,115
Debt securities issued by states of the United States and
political subdivisions of the states		0		342		0		342
Debt securities issued by foreign governments		0		73		0		73
Corporate debt securities		0		1,631		0		1,631
Federal agency mortgage-backed securities		0		43		0		43
Commercial mortgage-backed securities (non-agency)		0		39		0		39
Residential mortgage-backed securities (non-agency)		0		12		0		12
Mutual funds		0		8		0		8
Fixed income subtotal		1,115		2,148		0		3,263
Direct lending securities		0		0		54		54
Other debt obligations		0		14		0		14
Nuclear decommissioning trust fund investments subtotal(b)		2,797		3,960		54		6,811

Pledged assets for Zion Station decommissioning
Equity
Equity securities		20		0		0		20
Commingled funds		0		18		0		18
Equity funds subtotal		20		18		0		38
Fixed income
Debt securities issued by the U.S. Treasury and other U.S.
government corporations and agencies		79		17		0		96
Debt securities issued by states of the United States and
political subdivisions of the states		0		60		0		60
Corporate debt securities		0		278		0		278
Federal agency mortgage-backed securities		0		83		0		83
Commercial mortgage-backed securities (non-agency)		0		7		0		7
Commingled funds		0		28		0		28
Fixed income subtotal		79		473		0		552
Direct lending securities		0		0		59		59
Other debt obligations		0		1		0		1
Pledged assets for Zion Station decommissioning subtotal(c)		99		492		59		650

Rabbi trust investments
Cash equivalents		1		0		0		1
Mutual funds (d) (e)		12		0		0		12
Rabbi trust investments subtotal		13		0		0		13

Commodity mark-to-market derivative assets
Economic hedges		1,414		5,425		1,327		8,166
Proprietary trading		2,121		4,720		183		7,024
Effect of netting and allocation of collateral(f)		(3,710)		(8,423)		(261)		(12,394)
Commodity mark-to-market assets subtotal(g)		(175)		1,722		1,249		2,796
Interest Rate mark-to-market derivative assets		0		107		0		107
Other investments		2		0		17		19

Total assets		3,442		6,281		1,379		11,102

Liabilities
Commodity mark-to-market derivative liabilities
Economic hedges		(1,807)		(4,194)		(307)		(6,308)
Proprietary trading		(2,171)		(4,500)		(298)		(6,969)
Effect of netting and allocation of collateral(f)		3,978		7,825		268		12,071
Commodity mark-to-market liabilities subtotal		0		(869)		(337)		(1,206)
Interest rate mark-to-market derivative liabilities		0		(89)		0		(89)
Deferred compensation		0		(25)		0		(25)

Total liabilities		0		(983)		(337)		(1,320)

Total net assets	$	3,442	$	5,298	$	1,042	$	9,782

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.

(d) The $12 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 June 30, 2012 and December 31, 2011, respectively.

(g) The Level 3 balance includes current and noncurrent assets for Generation of $506 million and $0 million at June 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 June 30, 2011		Nuclear Decommissioning Trust Fund Investments		Mark-to-Market Derivatives			Total
Balance as of March 31, 2011		$	31	$	933		$	964
Total realized / unrealized losses
	Included in income		0		21	(a)		21
	Included in other comprehensive income		0		(178)	(b)		(178)
	Included in payable for Zion Station decommissioning		3		0			3
Changes in collateral			0		2			2
Purchases, sales, issuances and settlements
	Purchases		12		5			17
	Sales		(12)		0			(12)
Transfers out of Level 3 - Asset			0		(7)			(7)

Balance as of June 30, 2011		$	34	$	776		$	810

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

Six Months Ended June 30, 2011		Nuclear Decommissioning Trust Fund Investments		Mark-to-Market Derivatives			Total
Balance as of December 31, 2010		$	0	$	1,030		$	1,030
Total realized / unrealized gains
	Included in income		0		8	(a)		8
	Included in other comprehensive income		0		(233)	(b)		(233)
	Included in payable for Zion Station decommissioning		3		0			3
Changes in collateral			0		7			7
Purchases, sales, issuances and settlements
	Purchases		43		5			48
	Sales		(12)		0			(12)
Transfers out of Level 3 - Liability			0		(41)			(41)

Balance as of June 30, 2011		$	34	$	776		$	810

The amount of total gains included in income attributed to
	the change in unrealized gains (losses) related to assets and liabilities held for the six months ended June 30, 2011	$	0	$	23		$	23

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 June 30, 2012		$	(101)	$	30
Total gains (losses) included in income for the six months ended
	June 30, 2012	$	(25)	$	28
Change in the unrealized gains (losses) relating to assets and liabilities held for
	the three months ended June 30, 2012	$	(36)	$	21
Change in the unrealized gains relating to assets and liabilities held for
	the six months ended June 30, 2012	$	68	$	10

		Operating Revenue		Purchased Power and Fuel
Total gains included in income for the three months ended
	June 30, 2011	$	10	$	11
Total gains (losses) included in income for the six months ended June 30, 2011		$	7	$	1
Change in the unrealized gains relating to assets and liabilities
	held for the three months ended June 30, 2011	$	17	$	13
Change in the unrealized gains relating to assets and liabilities held for
	the six months ended June 30, 2011	$	21	$	2

Commonwealth Edison Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		June 30, 2012								December 31, 2011
		Carrying		Fair Value						Carrying		Fair
		Amount			Level 1		Level 2		Level 3	Amount		Value
Short-term liabilities		$	178	$	0	$	178	$	0	$	0	$	0
Long-term debt (including amounts
	due within one year)		5,216		0		6,174		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 June 30, 2012		Level 1		Level 2		Level 3		Total
Assets
Cash equivalents		$	3	$	0	$	0	$	3
Rabbi trust investments
Mutual funds			15		0		0		15
	Rabbi trust investment subtotal		15		0		0		15

Total assets			18		0		0		18

Liabilities
Deferred compensation obligation			0		(8)		0		(8)
Mark-to-market derivative liabilities (b)(c)			0		0		(617)		(617)

Total liabilities			0		(8)		(617)		(625)

Total net assets (liabilities)		$	18	$	(8)	$	(617)	$	(607)

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.

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

Three Months Ended June 30, 2012	Mark-to-Market Derivatives
Balance as of March 31, 2012	$	(823)
Total realized / unrealized gains included in regulatory assets (a)(b)		206
Balance as of June 30, 2012	$	(617)

Six Months Ended June 30, 2012	Mark-to-Market Derivatives
Balance as of December 31, 2011	$	(800)
Total realized / unrealized gains included in regulatory assets (a)(b)		183
Balance as of June 30, 2012	$	(617)

(a) Includes $14 million of increases in fair value and $121 million of decreases in fair value and realized gains due to settlements of $161 million and $308 million associated with ComEd's financial swap contract with Generation for the three and six months ended June 30, 2012, respectively. All items eliminate upon consolidation in Exelon's Consolidated Financial Statements.

(b) Includes $30 million of decreases in fair value and $5 million of increases in the fair value of floating-to-fixed energy swap contracts with unaffiliated suppliers for the three and six months ended June 30, 2012, respectively.

Three Months Ended June 30, 2011	Mark-to-Market Derivatives
Balance as of March 31, 2011	$	(875)
Total realized / unrealized gains included in regulatory assets (a)(b)		87
Balance as of June 30, 2011	$	(788)

Six Months Ended June 30, 2011	Mark-to-Market Derivatives
Balance as of December 31, 2010	$	(971)
Total realized / unrealized gains included in regulatory assets (a)(b)		183
Balance as of June 30, 2011	$	(788)

PECO Energy Co [Member]

Fair Value Tables [Line Items]

Fair value of financial liabilities recorded at the carrying amount

		June 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)		1,973		0		2,307		0		1,972		2,295
Long-term debt to financing trusts			184		0		180		0		184		174
Preferred securities			87		0		82		0		87		79

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

As of June 30, 2012	Level 1		Level 2		Level 3		Total
Assets
Cash equivalents	$	184	$	0	$	0	$	184
Rabbi trust investments - mutual funds(b)(c)		8		0		0		8

Total assets		192		0		0		192

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

Total liabilities		0		(18)		0		(18)

Total net assets (liabilities)	$	192	$	(18)	$	0	$	174

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 $13 million of the cash surrender value of life insurance investments at June 30, 2012 and December 31, 2011.

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

Three Months Ended June 30, 2011	Mark-to-Market Derivatives
Balance as of March 31, 2011	$	(7)
Total realized gains included in regulatory assets		3	(a)
Balance as of June 30, 2011	$	(4)

Six Months Ended June 30, 2011	Mark-to-Market Derivatives
Balance as of December 31, 2010	$	(9)
Total realized gains included in regulatory assets		5	(a)
Balance as of June 30, 2011	$	(4)

(a) Includes increases of $2 million and $3 million related to the settlement of PECO's block contract with Generation for the three and six months ended June 30, 2011, respectively, 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

		June 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)		1,961		0	2,270	0		2,101		2,377
Long-term debt to financing trusts			258		0	264	0		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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 14

-Subparagraph a

-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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 15

-Subparagraph b-d

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

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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 8: http://www.xbrl.org/2003/role/presentationRef

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

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