Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2012

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 March 31, 2012 of our assets and liabilities that are measured at fair value on a recurring basis (dollars in millions):

	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other			Balance at March 31, 2012
Assets
Nuclear decommissioning trust:
U.S. commingled equity funds	$	—	$	196		$	—		$	—		$	196
Fixed income securities:
U.S. Treasury	76		—			—			—			76
Cash and cash equivalent funds	—		15			—			(1		)(c)	14
Corporate debt	—		67			—			—			67
Mortgage-backed securities	—		82			—			—			82
Municipality bonds	—		88			—			—			88
Other	—		19			—			—			19
Subtotal nuclear decommissioning trust	76		467			—			(1		)	542
Cash Equivalents	12		—			—			—			12
Risk management activities — derivative instruments:
Commodity contracts	—		63			84			(59		)(b)	88
Total	$	88	$	530		$	84		$	(60	)	$	642
Liabilities:
Risk management activities — derivative instruments:
Commodity contracts	$	—	$	(271	)	$	(142	)	$	260	(b)	$	(153	)

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

(b)Represents counterparty netting, margin and collateral (see Note 8).

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

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 Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (a) (Level 3)			Other			Balance at December 31, 2011
Assets
Nuclear decommissioning trust:
U.S. commingled equity funds	$	—	$	175		$	—		$	—		$	175
Fixed income securities:
U.S. Treasury	69		—			—			—			69
Cash and cash equivalent funds	—		9			—			(1		)(c)	8
Corporate debt	—		73			—			—			73
Mortgage-backed securities	—		78			—			—			78
Municipality bonds	—		90			—			—			90
Other	—		21			—			—			21
Subtotal nuclear decommissioning trust	69		446			—			(1		)	514
Risk management activities — derivative instruments:
Commodity contracts	—		70			74			(64		)(b)	80
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 long-dated electricity contracts.

(b)Represents counterparty netting, margin and collateral (see Note 8).

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

Information regarding the entity's internally developed significant unobservable inputs used to value its level 3 instruments

	March 31, 2012 Fair Value (millions)
Commodity Contracts	Assets		Liabilities		Valuation Technique	Significant Unobservable Input	Range
Electricity:
Forward Contracts	$	79	$	106	Discounted cash flows	Electricity prices	$7.13 - $67.50 per MWh
Option Contracts	—		35		Option Model	Electricity prices	$21.15 - $94.23 per MWh
						Natural gas prices	$1.90 - $4.31 per mmbtu
						Electricity volatilities	14% - 83%
						Natural gas volatilities	17% - 50%
Natural Gas:
Forward Contracts	5		1		Discounted cash flows	Natural gas prices	$1.85 - $4.20 per mmbtu
Total	$	84	$	142

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

	Three Months Ended March 31,
Commodity Contracts	2012			2011
Net risk management activities balance at beginning of period	$	(51	)	$	(38	)
Total net gains (losses) realized/unrealized:
Included in earnings	1			1
Included in OCI	(5		)	2
Deferred as a regulatory asset or liability	(5		)	(7		)
Settlements	1			—
Transfers into Level 3 from Level 2	2			(5		)
Transfers from Level 3 into Level 2	(1		)	(1		)
Net risk management activities at end of period	$	(58	)	$	(48	)
Net unrealized gains included in earnings related to instruments still held at end of period	$	—		$	1