Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2011

Fair Value Measurements

Fair value of assets and liabilities that are measured at fair value on a recurring basis

The following table presents the fair value at December 31, 2011 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in millions):

	Quoted Pricesin ActiveMarkets forIdentical Assets(Level 1)		SignificantOtherObservable Inputs(Level 2)			SignificantUnobservableInputs (a)(Level 3)			Other			Balance atDecember 31, 2011
Assets
Risk management activities-derivative instruments:
Commodity contracts	$	—	$	70		$	74		$	(64	)(b)	$	80
Nuclear decommissioningtrust:
U.S. commingledequity funds	—		175			—			—			175
Fixed income securities:
U.S. Treasury	69		—			—			—			69
Cash and cashequivalent funds	—		9			—			(1		)(c)	8
Corporate debt	—		73			—			—			73
Mortgage-backed securities	—		78			—			—			78
Municipality bonds	—		90			—			—			90
Other	—		21			—			—			21
Subtotal nucleardecommissioning trust	69		446			—			(1		)	514
Total	$	69	$	516		$	74		$	(65	)	$	594
Liabilities
Risk management activities - derivative instruments:
Commodity contracts	$	—	$	(241	)	$	(125	)	$	229	(b)	$	(137	)

(a)Primarily consists of heat rate options and other long-dated electricity contracts.

(b)Represents counterparty netting, margin and collateral.  See Note 18.

(c)Represents nuclear decommissioning trust net pending securities sales and purchases.

The following table presents the fair value at December 31, 2010 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in millions):

	Quoted Pricesin ActiveMarkets forIdentical Assets(Level 1)			SignificantOtherObservable Inputs(Level 2)			SignificantUnobservableInputs (a)(Level 3)			Other			Balance atDecember 31, 2010
Assets
Cash equivalents	$	35		$	—		$	—		$	—		$	35
Risk management activities-derivative instruments:
Commodity contracts	—			80			61			(28		)(b)	113
Nuclear decommissioningtrust:
U.S. commingledequity funds	—			168			—			—			168
Fixed income securities:
U.S. Treasury	50			—			—			—			50
Cash and cashequivalent funds	—			22			—			—			22
Corporate debt	—			60			—			—			60
Mortgage-backed securities	—			81			—			—			81
Municipality bonds	—			79			—			—			79
Other	—			20			—			(10)		(c)	10
Subtotal nucleardecommissioning trust	50			430			—			(10		)	470
Total	$	85		$	510		$	61		$	(38	)	$	618
Liabilities
Risk management activities - derivative instruments:
Commodity contracts	$	(1	)	$	(280	)	$	(99	)	$	256	(b)	$	(124	)

(a)Primarily consists of long-dated electricity contracts.

(b)Represents counterparty netting, margin and collateral.  See Note 18.

(c)Represents nuclear decommissioning trust net pending securities sales and purchases.

Changes in fair value for assets and liabilities that are measured at fair value on a recurring basis using Level 3 inputs

	Year EndedDecember 31,
	2011			2010
Net risk management activities at beginning of period	$	(38	)	$	(10	)
Total net gains (losses) realized/unrealized:
Included in earnings	2			(1		)
Included in OCI	(5		)	(14		)
Deferred as a regulatory asset or liability	(10		)	(38		)
Settlements	11			19
Transfers into Level 3 from Level 2	(4		)	5
Transfers from Level 3 into Level 2	(7		)	1
Net risk management activities at end of period	$	(51	)	$	(38	)
Net unrealized gains (losses) included in earnings related to instruments still held at end of period	$	1		$	(1	)